Merge branch 'master' into test-build-for-example

7 years ago · 29c19f8a40
parent c713477ac8 ceb4779723
commit 29c19f8a40
29 changed files with 565 additions and 298 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -1,5 +1,71 @@
 # Changelog

+## 🌄 0.5.1
+
+- ### 🤕 Fixes
+
+  - **Child Process and output management - [fitzgen], [issue/287] [pull/392]**
+
+    Not exactly a "fix", but definitely a huge improvment in how child processes and their
+    output are handled by `wasm-pack`. Ever sat at a long prompt from `wasm-pack` and
+    wondered what was happening? No longer! Did `wasm-pack` eat your test output- no more!
+
+    [issue/287]: https://github.com/rustwasm/wasm-pack/issues/287
+    [pull/392]: https://github.com/rustwasm/wasm-pack/pull/392
+
+  - **Less scary missing field  messages - [mstallmo], [issue/393] [pull/394]**
+
+    After watching a livestream of someone using `wasm-pack`, [fitzgen] noted that folks
+    seemed pretty alarmed by the loud warning about missing optional manifest fields.
+    As a result, we are now downgrading those messages from WARN to INFO, and consolidating
+    them on a single line.
+
+    [issue/393]: https://github.com/rustwasm/wasm-pack/issues/393
+    [pull/394]: https://github.com/rustwasm/wasm-pack/pull/394
+  
+  - **Add `exit_status` to CLI errors - [konstin], [issue/291] [pull/387]**
+
+    We'd been hiding these- but we shouldn't have been!
+
+    [konstin]: https://github.com/konstin
+    [issue/291]: https://github.com/rustwasm/wasm-pack/issues/291
+    [pull/387]: https://github.com/rustwasm/wasm-pack/pull/387
+
+  - **Remove lingering forced nightly usage - [alexcrichton], [pull/383]**
+
+    In 0.5.0 we removed all forced nightly usage as we depend on `~1.30` which is now
+    available on both nightly and beta channels! We had a bit of a race condition with 
+    that PR and the `wasm-pack test` PR, and missed a few as a result! This removes all
+    lingering forced nightly, which only affected the `wasm-pack test` command.
+
+    [pull/383]: https://github.com/rustwasm/wasm-pack/pull/383
+
+  - **Fix `wasm-bindgen-test` dependency error message - [fitzgen], [issue/377] [pull/378]**
+
+    The error message about missing the `wasm-bindgen-test` dependency errantly stated
+    that the user was missing a `wasm-bindgen` dependency! We've fixed it to correctly
+    state the missing dependency now.
+
+    [issue/377]: https://github.com/rustwasm/wasm-pack/issues/377
+    [pull/378]: https://github.com/rustwasm/wasm-pack/pull/378
+
+  - **Fix prerequisites links in docs - [fitzgen], [pull/376]**
+
+    [pull/376]: https://github.com/rustwasm/wasm-pack/pull/376
+
+- ### 🛠️ Maintenance
+
+  - **Leverage `failure::Error` consistently - [drager], [issue/280] [pull/401]**
+
+    This PR finally makes it so that `wasm-pack` is handling errors in a consistent
+    way across the codebase. 
+
+    [drager]: https://github.com/drager
+    [issue/280]: https://github.com/rustwasm/wasm-pack/issues/280
+    [pull/401]: https://github.com/rustwasm/wasm-pack/pull/401
+
+  
+
 ## ☀️ 0.5.0

 - ### ✨ Features
--- a/Cargo.lock
+++ b/Cargo.lock
@ -92,7 +92,7 @@ dependencies = [
 "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_derive 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.30 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@ -159,7 +159,7 @@ dependencies = [
 "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
 "parking_lot 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
 "regex 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "termios 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "termios 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@ -174,22 +174,22 @@ dependencies = [

 [[package]]
 name = "curl"
-version = "0.4.17"
+version = "0.4.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "curl-sys 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)",
+ "curl-sys 0.4.13 (registry+https://github.com/rust-lang/crates.io-index)",
 "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
 "openssl-probe 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "openssl-sys 0.9.36 (registry+https://github.com/rust-lang/crates.io-index)",
- "schannel 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "schannel 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)",
 "socket2 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
 name = "curl-sys"
-version = "0.4.12"
+version = "0.4.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "cc 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
@ -223,7 +223,7 @@ name = "failure_derive"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
 "synstructure 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
@ -241,7 +241,7 @@ dependencies = [

 [[package]]
 name = "flate2"
-version = "1.0.2"
+version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
@ -288,7 +288,7 @@ dependencies = [
 "serde_derive 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
 "tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "termcolor 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "toml 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "toml 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "uuid 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

@ -359,7 +359,7 @@ dependencies = [

 [[package]]
 name = "lock_api"
-version = "0.1.3"
+version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "owning_ref 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
@ -486,7 +486,7 @@ name = "parking_lot"
 version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "lock_api 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lock_api 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
 "parking_lot_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

@ -514,7 +514,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
 name = "proc-macro2"
-version = "0.4.19"
+version = "0.4.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@ -525,7 +525,7 @@ name = "quote"
 version = "0.6.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@ -546,13 +546,21 @@ dependencies = [
 "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
 "fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
 "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_core 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
 name = "rand_core"
-version = "0.2.1"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
@ -636,7 +644,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
 name = "schannel"
-version = "0.1.13"
+version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "lazy_static 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@ -672,14 +680,14 @@ name = "serde_derive"
 version = "1.0.79"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
 name = "serde_json"
-version = "1.0.30"
+version = "1.0.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "itoa 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
@ -689,7 +697,7 @@ dependencies = [

 [[package]]
 name = "slog"
-version = "2.3.3"
+version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
@ -697,7 +705,7 @@ name = "slog-async"
 version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "slog 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "slog 2.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "take_mut 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@ -709,7 +717,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "isatty 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "slog 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "slog 2.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "term 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@ -745,21 +753,21 @@ source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
 name = "structopt"
-version = "0.2.10"
+version = "0.2.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "structopt-derive 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "structopt-derive 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
 name = "structopt-derive"
-version = "0.2.10"
+version = "0.2.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@ -767,17 +775,17 @@ name = "syn"
 version = "0.14.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
 name = "syn"
-version = "0.15.6"
+version = "0.15.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@ -787,7 +795,7 @@ name = "synstructure"
 version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)",
 "quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
 "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@ -860,7 +868,7 @@ dependencies = [

 [[package]]
 name = "termios"
-version = "0.3.0"
+version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
@ -894,7 +902,7 @@ dependencies = [

 [[package]]
 name = "toml"
-version = "0.4.6"
+version = "0.4.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
@ -959,14 +967,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"

 [[package]]
 name = "wasm-pack"
-version = "0.5.0"
+version = "0.5.1"
 dependencies = [
 "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
 "cargo_metadata 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "console 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "curl 0.4.17 (registry+https://github.com/rust-lang/crates.io-index)",
+ "curl 0.4.18 (registry+https://github.com/rust-lang/crates.io-index)",
 "failure 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
 "human-panic 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "indicatif 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "lazy_static 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@ -974,14 +982,14 @@ dependencies = [
 "parking_lot 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde_derive 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.30 (registry+https://github.com/rust-lang/crates.io-index)",
- "slog 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)",
+ "slog 2.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "slog-async 2.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "slog-term 2.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "structopt 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "structopt 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
 "tar 0.4.17 (registry+https://github.com/rust-lang/crates.io-index)",
 "tempfile 3.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "toml 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "toml 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "which 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "zip 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@ -1046,7 +1054,7 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
 "bzip2 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
 "msdos_time 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "podio 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "time 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)",
@ -1073,13 +1081,13 @@ dependencies = [
 "checksum cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
 "checksum console 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "ecd48adf136733979b49e15bc3b4c43cc0d3c85ece7bd08e6daa414c6fcb13e6"
 "checksum crc 1.8.1 (registry+https://github.com/rust-lang/crates.io-index)" = "d663548de7f5cca343f1e0a48d14dcfb0e9eb4e079ec58883b7251539fa10aeb"
-"checksum curl 0.4.17 (registry+https://github.com/rust-lang/crates.io-index)" = "c8172e96ecfb1a2bfe3843d9d7154099a15130cf4a2f658259c7aa9cc2b5d4ff"
-"checksum curl-sys 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)" = "78800a6de442f65dab6ce26c6f369c14fc585686432bf4b77119d2d384216c31"
+"checksum curl 0.4.18 (registry+https://github.com/rust-lang/crates.io-index)" = "a9e5285b49b44401518c947d3b808d14d99a538a6c9ffb3ec0205c11f9fc4389"
+"checksum curl-sys 0.4.13 (registry+https://github.com/rust-lang/crates.io-index)" = "08459503c415173da1ce6b41036a37b8bfdd86af46d45abb9964d4c61fe670ef"
 "checksum error-chain 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "07e791d3be96241c77c43846b665ef1384606da2cd2a48730abe606a12906e02"
 "checksum failure 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7efb22686e4a466b1ec1a15c2898f91fa9cb340452496dca654032de20ff95b9"
 "checksum failure_derive 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "946d0e98a50d9831f5d589038d2ca7f8f455b1c21028c0db0e84116a12696426"
 "checksum filetime 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "da4b9849e77b13195302c174324b5ba73eec9b236b24c221a61000daefb95c5f"
-"checksum flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "37847f133aae7acf82bb9577ccd8bda241df836787642654286e79679826a54b"
+"checksum flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4af030962d89d62aa52cd9492083b1cd9b2d1a77764878102a6c0f86b4d5444d"
 "checksum foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f6f339eb8adc052cd2ca78910fda869aefa38d22d5cb648e6485e4d3fc06f3b1"
 "checksum foreign-types-shared 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "00b0228411908ca8685dba7fc2cdd70ec9990a6e753e89b6ac91a84c40fbaf4b"
 "checksum fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2e9763c69ebaae630ba35f74888db465e49e259ba1bc0eda7d06f4a067615d82"
@ -1093,7 +1101,7 @@ dependencies = [
 "checksum lazy_static 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ca488b89a5657b0a2ecd45b95609b3e848cf1755da332a0da46e2b2b1cb371a7"
 "checksum libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)" = "76e3a3ef172f1a0b9a9ff0dd1491ae5e6c948b94479a3021819ba7d860c8645d"
 "checksum libz-sys 1.0.23 (registry+https://github.com/rust-lang/crates.io-index)" = "c7bdca442aa002a930e6eb2a71916cabe46d91ffec8df66db0abfb1bc83469ab"
-"checksum lock_api 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "949826a5ccf18c1b3a7c3d57692778d21768b79e46eb9dd07bfc4c2160036c54"
+"checksum lock_api 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "775751a3e69bde4df9b38dd00a1b5d6ac13791e4223d4a0506577f0dd27cfb7a"
 "checksum memchr 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "4b3629fe9fdbff6daa6c33b90f7c08355c1aca05a3d01fa8063b822fcf185f3b"
 "checksum miniz-sys 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "609ce024854aeb19a0ef7567d348aaa5a746b32fb72e336df7fcc16869d7e2b4"
 "checksum miniz_oxide 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "9ba430291c9d6cedae28bcd2d49d1c32fc57d60cd49086646c5dd5673a870eb5"
@ -1111,11 +1119,12 @@ dependencies = [
 "checksum parking_lot_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ad7f7e6ebdc79edff6fdcb87a55b620174f7a989e3eb31b65231f4af57f00b8c"
 "checksum pkg-config 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)" = "676e8eb2b1b4c9043511a9b7bea0915320d7e502b0a079fb03f9635a5252b18c"
 "checksum podio 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "780fb4b6698bbf9cf2444ea5d22411cef2953f0824b98f33cf454ec5615645bd"
-"checksum proc-macro2 0.4.19 (registry+https://github.com/rust-lang/crates.io-index)" = "ffe022fb8c8bd254524b0b3305906c1921fa37a84a644e29079a9e62200c3901"
+"checksum proc-macro2 0.4.20 (registry+https://github.com/rust-lang/crates.io-index)" = "3d7b7eaaa90b4a90a932a9ea6666c95a389e424eff347f0f793979289429feee"
 "checksum quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)" = "dd636425967c33af890042c483632d33fa7a18f19ad1d7ea72e8998c6ef8dea5"
 "checksum rand 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8356f47b32624fef5b3301c1be97e5944ecdd595409cc5da11d05f211db6cfbd"
 "checksum rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e464cd887e869cddcae8792a4ee31d23c7edd516700695608f5b98c67ee0131c"
-"checksum rand_core 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "edecf0f94da5551fc9b492093e30b041a891657db7940ee221f9d2f66e82eef2"
+"checksum rand_core 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "1961a422c4d189dfb50ffa9320bf1f2a9bd54ecb92792fb9477f99a1045f3372"
+"checksum rand_core 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "0905b6b7079ec73b314d4c748701f6931eb79fd97c668caa3f1899b22b32c6db"
 "checksum redox_syscall 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)" = "c214e91d3ecf43e9a4e41e578973adeb14b474f2bee858742d127af75a0112b1"
 "checksum redox_termios 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7e891cfe48e9100a70a3b6eb652fef28920c117d366339687bd5576160db0f76"
 "checksum regex 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "9329abc99e39129fcceabd24cf5d85b4671ef7c29c50e972bc5afe32438ec384"
@ -1126,24 +1135,24 @@ dependencies = [
 "checksum rustc-demangle 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "bcfe5b13211b4d78e5c2cadfebd7769197d95c639c35a50057eb4c05de811395"
 "checksum rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
 "checksum ryu 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "7153dd96dade874ab973e098cb62fcdbb89a03682e46b144fd09550998d4a4a7"
-"checksum schannel 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "dc1fabf2a7b6483a141426e1afd09ad543520a77ac49bd03c286e7696ccfd77f"
+"checksum schannel 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)" = "0e1a231dc10abf6749cfa5d7767f25888d484201accbd919b66ab5413c502d56"
 "checksum scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "94258f53601af11e6a49f722422f6e3425c52b06245a5cf9bc09908b174f5e27"
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
 "checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 "checksum serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)" = "84257ccd054dc351472528c8587b4de2dbf0dc0fe2e634030c1a90bfdacebaa9"
 "checksum serde_derive 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)" = "31569d901045afbff7a9479f793177fe9259819aff10ab4f89ef69bbc5f567fe"
-"checksum serde_json 1.0.30 (registry+https://github.com/rust-lang/crates.io-index)" = "7f60a296fed15c3edbbe9aa83b646531459e565c525b0ab628deb1a4b28e4180"
-"checksum slog 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "09e4f1d0276ac7d448d98db16f0dab0220c24d4842d88ce4dad4b306fa234f1d"
+"checksum serde_json 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)" = "43344e7ce05d0d8280c5940cabb4964bea626aa58b1ec0e8c73fa2a8512a38ce"
+"checksum slog 2.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "1e1a2eec401952cd7b12a84ea120e2d57281329940c3f93c2bf04f462539508e"
 "checksum slog-async 2.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e544d16c6b230d84c866662fe55e31aacfca6ae71e6fc49ae9a311cb379bfc2f"
 "checksum slog-term 2.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5951a808c40f419922ee014c15b6ae1cd34d963538b57d8a4778b9ca3fff1e0b"
 "checksum smallvec 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)" = "153ffa32fd170e9944f7e0838edf824a754ec4c1fc64746fcc9fe1f8fa602e5d"
 "checksum socket2 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "c4d11a52082057d87cb5caa31ad812f4504b97ab44732cd8359df2e9ff9f48e7"
 "checksum stable_deref_trait 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "dba1a27d3efae4351c8051072d619e3ade2820635c3958d826bfea39d59b54c8"
 "checksum strsim 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bb4f380125926a99e52bc279241539c018323fab05ad6368b56f93d9369ff550"
-"checksum structopt 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)" = "d8e9ad6a11096cbecdcca0cc6aa403fdfdbaeda2fb3323a39c98e6a166a1e45a"
-"checksum structopt-derive 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)" = "4cbce8ccdc62166bd594c14396a3242bf94c337a51dbfa9be1076dd74b3db2af"
+"checksum structopt 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "ca85f2c9a5a1e2d5ac686fc0be48e40f8ad803f5bbe31f692ff71eb2dd8aad45"
+"checksum structopt-derive 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "1383e5db585da799a5c4acc496c5c868e18bf82e658c00c75cc91038fa26b55f"
 "checksum syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)" = "261ae9ecaa397c42b960649561949d69311f08eeaea86a65696e6e46517cf741"
-"checksum syn 0.15.6 (registry+https://github.com/rust-lang/crates.io-index)" = "854b08a640fc8f54728fb95321e3ec485b365a97fe47609797c671addd1dde69"
+"checksum syn 0.15.9 (registry+https://github.com/rust-lang/crates.io-index)" = "b10ee269228fb723234fce98e9aac0eaed2bd5f1ad2f6930e8d5b93f04445a1a"
 "checksum synstructure 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "85bb9b7550d063ea184027c9b8c20ac167cd36d3e06b3a40bceb9d746dc1a7b7"
 "checksum take_mut 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f764005d11ee5f36500a149ace24e00e3da98b0158b3e2d53a7495660d3f4d60"
 "checksum tar 0.4.17 (registry+https://github.com/rust-lang/crates.io-index)" = "83b0d14b53dbfd62681933fadd651e815f99e6084b649e049ab99296e05ab3de"
@ -1152,11 +1161,11 @@ dependencies = [
 "checksum term 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "5e6b677dd1e8214ea1ef4297f85dbcbed8e8cdddb561040cc998ca2551c37561"
 "checksum termcolor 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "adc4587ead41bf016f11af03e55a624c06568b5a19db4e90fde573d805074f83"
 "checksum termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "689a3bdfaab439fd92bc87df5c4c78417d3cbe537487274e9b0b2dce76e92096"
-"checksum termios 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "70226acdf12d182df757d9fb07c0257a1558ec48c8059f607d6b38145ce4e2fa"
+"checksum termios 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "72b620c5ea021d75a735c943269bb07d30c9b77d6ac6b236bc8b5c496ef05625"
 "checksum textwrap 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "307686869c93e71f94da64286f9a9524c0f308a9e1c87a583de8e9c9039ad3f6"
 "checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"
 "checksum time 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)" = "d825be0eb33fda1a7e68012d51e9c7f451dc1a69391e7fdc197060bb8c56667b"
-"checksum toml 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "a0263c6c02c4db6c8f7681f9fd35e90de799ebd4cfdeab77a38f4ff6b3d8c0d9"
+"checksum toml 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)" = "4a2ecc31b0351ea18b3fe11274b8db6e4d82bce861bbb22e6dbed40417902c65"
 "checksum ucd-util 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "fd2be2d6639d0f8fe6cdda291ad456e23629558d466e2789d2c3e9892bda285d"
 "checksum unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "882386231c45df4700b275c7ff55b6f3698780a650026380e72dabe76fa46526"
 "checksum unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fc72304796d0818e357ead4e000d19c9c174ab23dc11093ac919054d20a6a7fc"
--- a/Cargo.toml
+++ b/Cargo.toml
@ -1,7 +1,7 @@
 [package]
 name = "wasm-pack"
 description = "pack up the wasm and publish it to npm!"
-version = "0.5.0"
+version = "0.5.1"
 authors = ["Ashley Williams <ashley666ashley@gmail.com>"]
 repository = "https://github.com/ashleygwilliams/wasm-pack.git"
 license = "MIT/Apache-2.0"
--- a/docs/index.html
+++ b/docs/index.html
@ -42,9 +42,9 @@
          <h2>📦✨ your favorite rust -> wasm workflow tool!</h2>
        </div>
        <div class="five columns" id="installer">
-          <a class="button button-primary" href="/wasm-pack/installer">✨ Install wasm-pack 0.5.0 ✨</a>
-          <p>24 Sep 2018 |
-            <a href="https://github.com/rustwasm/wasm-pack/releases/tag/v0.5.0">
+          <a class="button button-primary" href="/wasm-pack/installer">✨ Install wasm-pack 0.5.1 ✨</a>
+          <p>9 Oct 2018 |
+            <a href="https://github.com/rustwasm/wasm-pack/releases/tag/v0.5.1">
              Release Notes
            </a>
          </p>
--- a/src/binaries.rs
+++ b/src/binaries.rs
@ -138,7 +138,7 @@ pub fn install_binaries_from_targz_at_url<'a, I>(
    crate_path: &Path,
    url: &str,
    binaries: I,
-) -> Result<(), Error>
+) -> Result<(), failure::Error>
 where
    I: IntoIterator<Item = &'a str>,
 {
@ -175,7 +175,8 @@ where
                .map(|s| s.to_string_lossy())
                .collect::<Vec<_>>()
                .join(", "),
-        )))
+        ))
+        .into())
    }
 }

@ -186,7 +187,7 @@ pub fn install_binaries_from_zip_at_url<'a, I>(
    crate_path: &Path,
    url: &str,
    binaries: I,
-) -> Result<(), Error>
+) -> Result<(), failure::Error>
 where
    I: IntoIterator<Item = &'a str>,
 {
@ -226,7 +227,8 @@ where
                .map(|s| s.to_string_lossy())
                .collect::<Vec<_>>()
                .join(", "),
-        )))
+        ))
+        .into())
    }
 }

--- a/src/bindgen.rs
+++ b/src/bindgen.rs
@ -2,8 +2,10 @@

 use binaries::{self, bin_path, install_binaries_from_targz_at_url};
 use cargo_metadata;
+use child;
 use emoji;
 use error::Error;
+use failure::{self, ResultExt};
 use progressbar::Step;
 use slog::Logger;
 use std::path::{Path, PathBuf};
@ -23,7 +25,7 @@ pub fn install_wasm_bindgen(
    install_permitted: bool,
    step: &Step,
    log: &Logger,
-) -> Result<(), Error> {
+) -> Result<(), failure::Error> {
    // If the `wasm-bindgen` dependency is already met, print a message and return.
    if wasm_bindgen_path(log, root_path)
        .map(|bindgen_path| wasm_bindgen_version_check(&bindgen_path, version, log))
@ -38,7 +40,7 @@ pub fn install_wasm_bindgen(
    // permitted, return a configuration error.
    if !install_permitted {
        let msg = format!("wasm-bindgen v{} is not installed!", version);
-        return Error::crate_config(&msg);
+        return Err(Error::crate_config(&msg).into());
    }

    let msg = format!("{}Installing wasm-bindgen...", emoji::DOWN_ARROW);
@ -49,12 +51,15 @@ pub fn install_wasm_bindgen(
            log,
            "could not download pre-built `wasm-bindgen`: {}. Falling back to `cargo install`.", e
        );
-        cargo_install_wasm_bindgen(root_path, version)
+        cargo_install_wasm_bindgen(log, root_path, version)
    })
 }

 /// Download a tarball containing a pre-built `wasm-bindgen` binary.
-pub fn download_prebuilt_wasm_bindgen(root_path: &Path, version: &str) -> Result<(), Error> {
+pub fn download_prebuilt_wasm_bindgen(
+    root_path: &Path,
+    version: &str,
+) -> Result<(), failure::Error> {
    let target = if target::LINUX && target::x86_64 {
        "x86_64-unknown-linux-musl"
    } else if target::MACOS && target::x86_64 {
@ -64,7 +69,8 @@ pub fn download_prebuilt_wasm_bindgen(root_path: &Path, version: &str) -> Result
    } else {
        return Err(Error::unsupported(
            "there are no pre-built `wasm-bindgen` binaries for this target",
-        ));
+        )
+        .into());
    };

    let url = format!(
@ -82,28 +88,23 @@ pub fn download_prebuilt_wasm_bindgen(root_path: &Path, version: &str) -> Result

 /// Use `cargo install` to install the `wasm-bindgen` CLI locally into the given
 /// crate.
-pub fn cargo_install_wasm_bindgen(crate_path: &Path, version: &str) -> Result<(), Error> {
-    let output = Command::new("cargo")
-        .arg("install")
+pub fn cargo_install_wasm_bindgen(
+    logger: &Logger,
+    crate_path: &Path,
+    version: &str,
+) -> Result<(), failure::Error> {
+    let mut cmd = Command::new("cargo");
+    cmd.arg("install")
        .arg("--force")
        .arg("wasm-bindgen-cli")
        .arg("--version")
        .arg(version)
        .arg("--root")
-        .arg(crate_path)
-        .output()?;
-    if !output.status.success() {
-        let message = "Installing wasm-bindgen failed".to_string();
-        let s = String::from_utf8_lossy(&output.stderr);
-        Err(Error::Cli {
-            message,
-            stderr: s.to_string(),
-            exit_status: output.status,
-        })
-    } else {
-        assert!(binaries::local_bin_path(crate_path, "wasm-bindgen").is_file());
-        Ok(())
-    }
+        .arg(crate_path);
+
+    child::run(logger, cmd, "cargo install").context("Installing wasm-bindgen with cargo")?;
+    assert!(binaries::local_bin_path(crate_path, "wasm-bindgen").is_file());
+    Ok(())
 }

 /// Run the `wasm-bindgen` CLI to generate bindings for the current crate's
@ -117,7 +118,7 @@ pub fn wasm_bindgen_build(
    debug: bool,
    step: &Step,
    log: &Logger,
-) -> Result<(), Error> {
+) -> Result<(), failure::Error> {
    let msg = format!("{}Running WASM-bindgen...", emoji::RUNNER);
    PBAR.step(step, &msg);

@ -161,27 +162,20 @@ pub fn wasm_bindgen_build(
            cmd.arg("--debug");
        }

-        let output = cmd.output()?;
-        if !output.status.success() {
-            let s = String::from_utf8_lossy(&output.stderr);
-            Error::cli("wasm-bindgen failed to execute properly", s, output.status)
-        } else {
-            Ok(())
-        }
+        child::run(log, cmd, "wasm-bindgen").context("Running the wasm-bindgen CLI")?;
+        Ok(())
    } else {
-        Error::crate_config("Could not find `wasm-bindgen`")
+        Err(Error::crate_config("Could not find `wasm-bindgen`").into())
    }
 }

 /// Check if the `wasm-bindgen` dependency is locally satisfied.
 fn wasm_bindgen_version_check(bindgen_path: &PathBuf, dep_version: &str, log: &Logger) -> bool {
-    Command::new(bindgen_path)
-        .arg("--version")
-        .output()
-        .ok()
-        .filter(|output| output.status.success())
-        .map(|output| {
-            String::from_utf8_lossy(&output.stdout)
+    let mut cmd = Command::new(bindgen_path);
+    cmd.arg("--version");
+    child::run(log, cmd, "wasm-bindgen")
+        .map(|stdout| {
+            stdout
                .trim()
                .split_whitespace()
                .nth(1)
--- a/src/build.rs
+++ b/src/build.rs
@ -1,15 +1,18 @@
 //! Building a Rust crate into a `.wasm` binary.

+use child;
 use emoji;
 use error::Error;
+use failure::ResultExt;
 use progressbar::Step;
+use slog::Logger;
 use std::path::Path;
 use std::process::Command;
 use std::str;
 use PBAR;

 /// Ensure that `rustc` is present and that it is >= 1.30.0
-pub fn check_rustc_version(step: &Step) -> Result<String, Error> {
+pub fn check_rustc_version(step: &Step) -> Result<String, failure::Error> {
    let msg = format!("{}Checking `rustc` version...", emoji::CRAB);
    PBAR.step(step, &msg);
    let local_minor_version = rustc_minor_version();
@ -22,14 +25,14 @@ pub fn check_rustc_version(step: &Step) -> Result<String, Error> {
                  mv.to_string()
                ),
                local_minor_version: mv.to_string(),
-              })
+              }.into())
            } else {
              Ok(mv.to_string())
            }
      },
      None => Err(Error::RustcMissing {
        message: "We can't figure out what your Rust version is- which means you might not have Rust installed. Please install Rust version 1.30.0 or higher.".to_string(),
-      }),
+      }.into()),
    }
 }

@ -54,28 +57,23 @@ fn rustc_minor_version() -> Option<u32> {

 /// Ensure that `rustup` has the `wasm32-unknown-unknown` target installed for
 /// current toolchain
-pub fn rustup_add_wasm_target(step: &Step) -> Result<(), Error> {
+pub fn rustup_add_wasm_target(log: &Logger, step: &Step) -> Result<(), failure::Error> {
    let msg = format!("{}Adding WASM target...", emoji::TARGET);
    PBAR.step(step, &msg);
-    let output = Command::new("rustup")
-        .arg("target")
-        .arg("add")
-        .arg("wasm32-unknown-unknown")
-        .output()?;
-    if !output.status.success() {
-        let s = String::from_utf8_lossy(&output.stderr);
-        Error::cli(
-            "Adding the wasm32-unknown-unknown target failed",
-            s,
-            output.status,
-        )
-    } else {
-        Ok(())
-    }
+    let mut cmd = Command::new("rustup");
+    cmd.arg("target").arg("add").arg("wasm32-unknown-unknown");
+    child::run(log, cmd, "rustup")
+        .context("Adding the wasm32-unknown-unknown target with rustup")?;
+    Ok(())
 }

 /// Run `cargo build` targetting `wasm32-unknown-unknown`.
-pub fn cargo_build_wasm(path: &Path, debug: bool, step: &Step) -> Result<(), Error> {
+pub fn cargo_build_wasm(
+    log: &Logger,
+    path: &Path,
+    debug: bool,
+    step: &Step,
+) -> Result<(), failure::Error> {
    let msg = format!("{}Compiling to WASM...", emoji::CYCLONE);
    PBAR.step(step, &msg);
    let mut cmd = Command::new("cargo");
@ -84,32 +82,22 @@ pub fn cargo_build_wasm(path: &Path, debug: bool, step: &Step) -> Result<(), Err
        cmd.arg("--release");
    }
    cmd.arg("--target").arg("wasm32-unknown-unknown");
-    let output = cmd.output()?;
-
-    if !output.status.success() {
-        let s = String::from_utf8_lossy(&output.stderr);
-        Error::cli("Compilation of your program failed", s, output.status)
-    } else {
-        Ok(())
-    }
+    child::run(log, cmd, "cargo build").context("Compiling your crate to WebAssembly")?;
+    Ok(())
 }

 /// Run `cargo build --tests` targetting `wasm32-unknown-unknown`.
-pub fn cargo_build_wasm_tests(path: &Path, debug: bool) -> Result<(), Error> {
-    let output = {
-        let mut cmd = Command::new("cargo");
-        cmd.current_dir(path).arg("build").arg("--tests");
-        if !debug {
-            cmd.arg("--release");
-        }
-        cmd.arg("--target").arg("wasm32-unknown-unknown");
-        cmd.output()?
-    };
-
-    if !output.status.success() {
-        let s = String::from_utf8_lossy(&output.stderr);
-        Error::cli("Compilation of your program failed", s, output.status)
-    } else {
-        Ok(())
+pub fn cargo_build_wasm_tests(
+    log: &Logger,
+    path: &Path,
+    debug: bool,
+) -> Result<(), failure::Error> {
+    let mut cmd = Command::new("cargo");
+    cmd.current_dir(path).arg("build").arg("--tests");
+    if !debug {
+        cmd.arg("--release");
    }
+    cmd.arg("--target").arg("wasm32-unknown-unknown");
+    child::run(log, cmd, "cargo build").context("Compilation of your program failed")?;
+    Ok(())
 }
--- a/src/child.rs
+++ b/src/child.rs
@ -0,0 +1,177 @@
+//! Utilties for managing child processes.
+//!
+//! This module helps us ensure that all child processes that we spawn get
+//! properly logged and their output is logged as well.
+
+use error::Error;
+use failure;
+use slog::Logger;
+use std::{
+    io::{self, Read},
+    mem, process, string,
+    sync::mpsc,
+    thread,
+};
+use PBAR;
+
+#[derive(Debug)]
+enum OutputFragment {
+    Stdout(Vec<u8>),
+    Stderr(Vec<u8>),
+}
+
+/// Read data from the give reader and send it as an `OutputFragment` over the
+/// given sender.
+fn read_and_send<R, F>(
+    mut reader: R,
+    sender: mpsc::Sender<OutputFragment>,
+    mut map: F,
+) -> io::Result<()>
+where
+    R: Read,
+    F: FnMut(Vec<u8>) -> OutputFragment,
+{
+    let mut buf = vec![0; 1024];
+    loop {
+        match reader.read(&mut buf) {
+            Err(e) => {
+                if e.kind() == io::ErrorKind::Interrupted {
+                    continue;
+                } else {
+                    return Err(e);
+                }
+            }
+            Ok(0) => return Ok(()),
+            Ok(n) => {
+                buf.truncate(n);
+                let buf = mem::replace(&mut buf, vec![0; 1024]);
+                sender.send(map(buf)).unwrap();
+            }
+        }
+    }
+}
+
+/// Accumulates output from a stream of output fragments and calls a callback on
+/// each complete line as it is accumulating.
+struct OutputAccumulator<F> {
+    result: String,
+    in_progress: Vec<u8>,
+    on_each_line: F,
+}
+
+impl<F> OutputAccumulator<F>
+where
+    F: FnMut(&str),
+{
+    /// Construct a new output accumulator with the given `on_each_line`
+    /// callback.
+    fn new(on_each_line: F) -> OutputAccumulator<F> {
+        OutputAccumulator {
+            result: String::new(),
+            in_progress: Vec::new(),
+            on_each_line,
+        }
+    }
+
+    /// Add another fragment of output to the accumulation, calling the
+    /// `on_each_line` callback for any complete lines we accumulate.
+    fn push(&mut self, fragment: Vec<u8>) -> Result<(), string::FromUtf8Error> {
+        debug_assert!(!fragment.is_empty());
+        self.in_progress.extend(fragment);
+
+        if let Some((last_newline, _)) = self
+            .in_progress
+            .iter()
+            .cloned()
+            .enumerate()
+            .rev()
+            .find(|(_, ch)| *ch == b'\n')
+        {
+            let next_in_progress: Vec<u8> = self.in_progress[last_newline + 1..]
+                .iter()
+                .cloned()
+                .collect();
+            let mut these_lines = mem::replace(&mut self.in_progress, next_in_progress);
+            these_lines.truncate(last_newline + 1);
+            let these_lines = String::from_utf8(these_lines)?;
+            for line in these_lines.lines() {
+                (self.on_each_line)(line);
+            }
+            self.result.push_str(&these_lines);
+        }
+
+        Ok(())
+    }
+
+    /// Finish accumulation, run the `on_each_line` callback on the final line
+    /// (if any), and return the accumulated output.
+    fn finish(mut self) -> Result<String, string::FromUtf8Error> {
+        if !self.in_progress.is_empty() {
+            let last_line = String::from_utf8(self.in_progress)?;
+            (self.on_each_line)(&last_line);
+            self.result.push_str(&last_line);
+        }
+        Ok(self.result)
+    }
+}
+
+/// Run the given command and return its stdout.
+pub fn run(
+    logger: &Logger,
+    mut command: process::Command,
+    command_name: &str,
+) -> Result<String, failure::Error> {
+    info!(logger, "Running {:?}", command);
+
+    let mut child = command
+        .stdout(process::Stdio::piped())
+        .stderr(process::Stdio::piped())
+        .spawn()?;
+
+    let stdout = child.stdout.take().unwrap();
+    let stderr = child.stderr.take().unwrap();
+
+    let (send, recv) = mpsc::channel();
+    let stdout_send = send.clone();
+    let stderr_send = send;
+
+    // Because pipes have a fixed-size buffer, we need to keep reading stdout
+    // and stderr on a separate thread to avoid potential dead locks with
+    // waiting on the child process.
+
+    let stdout_handle =
+        thread::spawn(move || read_and_send(stdout, stdout_send, OutputFragment::Stdout));
+    let stderr_handle =
+        thread::spawn(move || read_and_send(stderr, stderr_send, OutputFragment::Stderr));
+
+    let mut stdout = OutputAccumulator::new(|line| {
+        info!(logger, "{} (stdout): {}", command_name, line);
+        PBAR.message(line)
+    });
+    let mut stderr = OutputAccumulator::new(|line| {
+        info!(logger, "{} (stderr): {}", command_name, line);
+        PBAR.message(line)
+    });
+
+    for output in recv {
+        match output {
+            OutputFragment::Stdout(line) => stdout.push(line)?,
+            OutputFragment::Stderr(line) => stderr.push(line)?,
+        };
+    }
+
+    let stdout = stdout.finish()?;
+    let stderr = stderr.finish()?;
+
+    // Join the threads reading the child's output to make sure the finish OK.
+    stdout_handle.join().unwrap()?;
+    stderr_handle.join().unwrap()?;
+
+    let exit = child.wait()?;
+    if exit.success() {
+        return Ok(stdout);
+    } else {
+        let msg = format!("`{}` did not exit successfully", command_name);
+        return Err(Error::cli(&msg, stdout.into(), stderr.into(), exit).into());
+    }
+}
--- a/src/command/build.rs
+++ b/src/command/build.rs
@ -55,7 +55,7 @@ impl FromStr for BuildMode {
            "no-install" => Ok(BuildMode::Noinstall),
            "normal" => Ok(BuildMode::Normal),
            "force" => Ok(BuildMode::Force),
-            _ => Error::crate_config(&format!("Unknown build mode: {}", s)).map(|_| unreachable!()),
+            _ => Err(Error::crate_config(&format!("Unknown build mode: {}", s))),
        }
    }
 }
@ -94,11 +94,11 @@ pub struct BuildOptions {
    pub out_dir: String,
 }

-type BuildStep = fn(&mut Build, &Step, &Logger) -> Result<(), Error>;
+type BuildStep = fn(&mut Build, &Step, &Logger) -> Result<(), failure::Error>;

 impl Build {
    /// Construct a build command from the given options.
-    pub fn try_from_opts(build_opts: BuildOptions) -> Result<Self, Error> {
+    pub fn try_from_opts(build_opts: BuildOptions) -> Result<Self, failure::Error> {
        let crate_path = set_crate_path(build_opts.path)?;
        let crate_name = manifest::get_crate_name(&crate_path)?;
        let out_dir = crate_path.join(PathBuf::from(build_opts.out_dir));
@ -117,7 +117,7 @@ impl Build {
    }

    /// Execute this `Build` command.
-    pub fn run(&mut self, log: &Logger) -> Result<(), Error> {
+    pub fn run(&mut self, log: &Logger) -> Result<(), failure::Error> {
        let process_steps = Build::get_process_steps(&self.mode);

        let mut step_counter = Step::new(process_steps.len());
@ -188,7 +188,11 @@ impl Build {
        }
    }

-    fn step_check_rustc_version(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_check_rustc_version(
+        &mut self,
+        step: &Step,
+        log: &Logger,
+    ) -> Result<(), failure::Error> {
        info!(&log, "Checking rustc version...");
        let version = build::check_rustc_version(step)?;
        let msg = format!("rustc version is {}.", version);
@ -196,23 +200,23 @@ impl Build {
        Ok(())
    }

-    fn step_check_crate_config(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_check_crate_config(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(&log, "Checking crate configuration...");
        manifest::check_crate_config(&self.crate_path, step)?;
        info!(&log, "Crate is correctly configured.");
        Ok(())
    }

-    fn step_add_wasm_target(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_add_wasm_target(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(&log, "Adding wasm-target...");
-        build::rustup_add_wasm_target(step)?;
+        build::rustup_add_wasm_target(log, step)?;
        info!(&log, "Adding wasm-target was successful.");
        Ok(())
    }

-    fn step_build_wasm(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_build_wasm(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(&log, "Building wasm...");
-        build::cargo_build_wasm(&self.crate_path, self.debug, step)?;
+        build::cargo_build_wasm(log, &self.crate_path, self.debug, step)?;

        info!(
            &log,
@ -226,14 +230,14 @@ impl Build {
        Ok(())
    }

-    fn step_create_dir(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_create_dir(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(&log, "Creating a pkg directory...");
        create_pkg_dir(&self.out_dir, step)?;
        info!(&log, "Created a pkg directory at {:#?}.", &self.crate_path);
        Ok(())
    }

-    fn step_create_json(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_create_json(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(&log, "Writing a package.json...");
        manifest::write_package_json(
            &self.crate_path,
@ -251,14 +255,18 @@ impl Build {
        Ok(())
    }

-    fn step_copy_readme(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_copy_readme(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(&log, "Copying readme from crate...");
        readme::copy_from_crate(&self.crate_path, &self.out_dir, step)?;
        info!(&log, "Copied readme from crate to {:#?}.", &self.out_dir);
        Ok(())
    }

-    fn step_install_wasm_bindgen(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_install_wasm_bindgen(
+        &mut self,
+        step: &Step,
+        log: &Logger,
+    ) -> Result<(), failure::Error> {
        info!(&log, "Identifying wasm-bindgen dependency...");
        let lockfile = Lockfile::new(&self.crate_path)?;
        let bindgen_version = lockfile.require_wasm_bindgen()?;
@ -288,7 +296,7 @@ impl Build {
        Ok(())
    }

-    fn step_run_wasm_bindgen(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_run_wasm_bindgen(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(&log, "Building the wasm bindings...");
        bindgen::wasm_bindgen_build(
            &self.crate_path,
--- a/src/command/login.rs
+++ b/src/command/login.rs
@ -1,4 +1,3 @@
-use error::Error;
 use npm;
 use slog::Logger;
 use std::result;
@ -10,7 +9,7 @@ pub fn login(
    always_auth: bool,
    auth_type: Option<String>,
    log: &Logger,
-) -> result::Result<(), Error> {
+) -> result::Result<(), failure::Error> {
    let registry = registry.unwrap_or(npm::DEFAULT_NPM_REGISTRY.to_string());

    info!(&log, "Logging in to npm...");
@ -23,7 +22,7 @@ pub fn login(
        &auth_type
    );
    info!(&log, "npm info located in the npm debug log");
-    npm::npm_login(&registry, &scope, always_auth, &auth_type)?;
+    npm::npm_login(log, &registry, &scope, always_auth, &auth_type)?;
    info!(&log, "Logged you in!");

    PBAR.message(&format!("👋  logged you in!"));
--- a/src/command/mod.rs
+++ b/src/command/mod.rs
@ -84,7 +84,7 @@ pub enum Command {
 }

 /// Run a command with the given logger!
-pub fn run_wasm_pack(command: Command, log: &Logger) -> result::Result<(), Error> {
+pub fn run_wasm_pack(command: Command, log: &Logger) -> result::Result<(), failure::Error> {
    // Run the correct command based off input and store the result of it so that we can clear
    // the progress bar then return it
    let status = match command {
@ -129,7 +129,12 @@ pub fn run_wasm_pack(command: Command, log: &Logger) -> result::Result<(), Error
        Ok(_) => {}
        Err(ref e) => {
            error!(&log, "{}", e);
-            PBAR.error(e.error_type());
+            for c in e.iter_chain() {
+                if let Some(e) = c.downcast_ref::<Error>() {
+                    PBAR.error(e.error_type());
+                    break;
+                }
+            }
        }
    }

--- a/src/command/pack.rs
+++ b/src/command/pack.rs
@ -8,7 +8,7 @@ use PBAR;

 /// Executes the 'npm pack' command on the 'pkg' directory
 /// which creates a tarball that can be published to the NPM registry
-pub fn pack(path: Option<PathBuf>, log: &Logger) -> result::Result<(), Error> {
+pub fn pack(path: Option<PathBuf>, log: &Logger) -> result::Result<(), failure::Error> {
    let crate_path = set_crate_path(path)?;

    info!(&log, "Packing up the npm package...");
@ -18,7 +18,7 @@ pub fn pack(path: Option<PathBuf>, log: &Logger) -> result::Result<(), Error> {
            &crate_path, &crate_path
        ),
    })?;
-    npm::npm_pack(&pkg_directory.to_string_lossy())?;
+    npm::npm_pack(log, &pkg_directory.to_string_lossy())?;
    info!(
        &log,
        "Your package is located at {:#?}",
--- a/src/command/publish/mod.rs
+++ b/src/command/publish/mod.rs
@ -16,7 +16,7 @@ pub fn publish(
    path: Option<PathBuf>,
    access: Option<Access>,
    log: &Logger,
-) -> result::Result<(), Error> {
+) -> result::Result<(), failure::Error> {
    let crate_path = set_crate_path(path)?;

    info!(&log, "Publishing the npm package...");
@ -28,7 +28,7 @@ pub fn publish(
        ),
    })?;

-    npm::npm_publish(&pkg_directory.to_string_lossy(), access)?;
+    npm::npm_publish(log, &pkg_directory.to_string_lossy(), access)?;
    info!(&log, "Published your package!");

    PBAR.message("💥  published your package!");
--- a/src/command/test.rs
+++ b/src/command/test.rs
@ -94,11 +94,11 @@ pub struct Test {
    test_runner_path: Option<PathBuf>,
 }

-type TestStep = fn(&mut Test, &Step, &Logger) -> Result<(), Error>;
+type TestStep = fn(&mut Test, &Step, &Logger) -> Result<(), failure::Error>;

 impl Test {
    /// Construct a test command from the given options.
-    pub fn try_from_opts(test_opts: TestOptions) -> Result<Self, Error> {
+    pub fn try_from_opts(test_opts: TestOptions) -> Result<Self, failure::Error> {
        let TestOptions {
            path,
            node,
@ -124,18 +124,18 @@ impl Test {
        let any_browser = chrome || firefox || safari;

        if !node && !any_browser {
-            return Error::crate_config(
+            return Err(Error::crate_config(
                "Must specify at least one of `--node`, `--chrome`, `--firefox`, or `--safari`",
            )
-            .map(|_| unreachable!());
+            .into());
        }

        if headless && !any_browser {
-            return Error::crate_config(
+            return Err(Error::crate_config(
                "The `--headless` flag only applies to browser tests. Node does not provide a UI, \
                 so it doesn't make sense to talk about a headless version of Node tests.",
            )
-            .map(|_| unreachable!());
+            .into());
        }

        Ok(Test {
@ -155,7 +155,7 @@ impl Test {
    }

    /// Execute this test command.
-    pub fn run(mut self, log: &Logger) -> Result<(), Error> {
+    pub fn run(mut self, log: &Logger) -> Result<(), failure::Error> {
        let process_steps = self.get_process_steps();
        let mut step_counter = Step::new(process_steps.len());

@ -227,40 +227,48 @@ impl Test {
        }
    }

-    fn step_check_rustc_version(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_check_rustc_version(
+        &mut self,
+        step: &Step,
+        log: &Logger,
+    ) -> Result<(), failure::Error> {
        info!(log, "Checking rustc version...");
        let _ = build::check_rustc_version(step)?;
        info!(log, "Rustc version is correct.");
        Ok(())
    }

-    fn step_check_crate_config(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_check_crate_config(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(log, "Checking crate configuration...");
        manifest::check_crate_config(&self.crate_path, step)?;
        info!(log, "Crate is correctly configured.");
        Ok(())
    }

-    fn step_add_wasm_target(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_add_wasm_target(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(&log, "Adding wasm-target...");
-        build::rustup_add_wasm_target(step)?;
+        build::rustup_add_wasm_target(log, step)?;
        info!(&log, "Adding wasm-target was successful.");
        Ok(())
    }

-    fn step_build_tests(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_build_tests(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        info!(log, "Compiling tests to wasm...");

        let msg = format!("{}Compiling tests to WASM...", emoji::CYCLONE);
        PBAR.step(step, &msg);

-        build::cargo_build_wasm_tests(&self.crate_path, !self.release)?;
+        build::cargo_build_wasm_tests(log, &self.crate_path, !self.release)?;

        info!(log, "Finished compiling tests to wasm.");
        Ok(())
    }

-    fn step_install_wasm_bindgen(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_install_wasm_bindgen(
+        &mut self,
+        step: &Step,
+        log: &Logger,
+    ) -> Result<(), failure::Error> {
        info!(&log, "Identifying wasm-bindgen dependency...");
        let lockfile = Lockfile::new(&self.crate_path)?;
        let bindgen_version = lockfile.require_wasm_bindgen()?;
@ -277,7 +285,7 @@ impl Test {
                 wasm-bindgen-test = \"0.2\"",
                style("wasm-bindgen-test").bold().dim(),
            );
-            return Err(Error::CrateConfig { message });
+            return Err(Error::CrateConfig { message }.into());
        }

        let install_permitted = match self.mode {
@ -310,7 +318,7 @@ impl Test {
        Ok(())
    }

-    fn step_test_node(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_test_node(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        assert!(self.node);
        info!(log, "Running tests in node...");
        PBAR.step(step, "Running tests in node...");
@ -327,7 +335,7 @@ impl Test {
        Ok(())
    }

-    fn step_get_chromedriver(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_get_chromedriver(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        PBAR.step(step, "Getting chromedriver...");
        assert!(self.chrome && self.chromedriver.is_none());

@ -339,7 +347,7 @@ impl Test {
        Ok(())
    }

-    fn step_test_chrome(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_test_chrome(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        PBAR.step(step, "Running tests in Chrome...");

        let chromedriver = self.chromedriver.as_ref().unwrap().display().to_string();
@ -366,10 +374,11 @@ impl Test {
            envs.push(("NO_HEADLESS", "1"));
        }

-        test::cargo_test_wasm(&self.crate_path, self.release, log, envs)
+        test::cargo_test_wasm(&self.crate_path, self.release, log, envs)?;
+        Ok(())
    }

-    fn step_get_geckodriver(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_get_geckodriver(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        PBAR.step(step, "Getting geckodriver...");
        assert!(self.firefox && self.geckodriver.is_none());

@ -381,7 +390,7 @@ impl Test {
        Ok(())
    }

-    fn step_test_firefox(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_test_firefox(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        PBAR.step(step, "Running tests in Firefox...");

        let geckodriver = self.geckodriver.as_ref().unwrap().display().to_string();
@ -408,10 +417,11 @@ impl Test {
            envs.push(("NO_HEADLESS", "1"));
        }

-        test::cargo_test_wasm(&self.crate_path, self.release, log, envs)
+        test::cargo_test_wasm(&self.crate_path, self.release, log, envs)?;
+        Ok(())
    }

-    fn step_get_safaridriver(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_get_safaridriver(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        PBAR.step(step, "Getting safaridriver...");
        assert!(self.safari && self.safaridriver.is_none());

@ -419,7 +429,7 @@ impl Test {
        Ok(())
    }

-    fn step_test_safari(&mut self, step: &Step, log: &Logger) -> Result<(), Error> {
+    fn step_test_safari(&mut self, step: &Step, log: &Logger) -> Result<(), failure::Error> {
        PBAR.step(step, "Running tests in Safari...");

        let safaridriver = self.safaridriver.as_ref().unwrap().display().to_string();
@ -446,6 +456,7 @@ impl Test {
            envs.push(("NO_HEADLESS", "1"));
        }

-        test::cargo_test_wasm(&self.crate_path, self.release, log, envs)
+        test::cargo_test_wasm(&self.crate_path, self.release, log, envs)?;
+        Ok(())
    }
 }
--- a/src/command/utils.rs
+++ b/src/command/utils.rs
@ -1,7 +1,7 @@
 //! Utility functions for commands.

 use emoji;
-use error::Error;
+use failure;
 use progressbar::Step;
 use std::fs;
 use std::io;
@ -20,7 +20,7 @@ pub fn set_crate_path(path: Option<PathBuf>) -> io::Result<PathBuf> {
 }

 /// Construct our `pkg` directory in the crate.
-pub fn create_pkg_dir(out_dir: &Path, step: &Step) -> Result<(), Error> {
+pub fn create_pkg_dir(out_dir: &Path, step: &Step) -> Result<(), failure::Error> {
    let msg = format!("{}Creating a pkg directory...", emoji::FOLDER);
    PBAR.step(step, &msg);
    fs::create_dir_all(&out_dir)?;
--- a/src/error.rs
+++ b/src/error.rs
@ -48,14 +48,17 @@ pub enum Error {

    /// An error invoking another CLI tool.
    #[fail(
-        display = "Process exited with {}: {}. stderr:\n\n{}",
+        display = "Process exited with {}: {}.\n\nstdout:{}\n\nstderr:\n\n{}",
        exit_status,
        message,
+        stdout,
        stderr
    )]
    Cli {
        /// Error message.
        message: String,
+        /// The underlying CLI's `stdout` output.
+        stdout: String,
        /// The underlying CLI's `stderr` output.
        stderr: String,
        /// The exit status of the subprocess
@ -101,19 +104,20 @@ pub enum Error {

 impl Error {
    /// Construct a CLI error.
-    pub fn cli(message: &str, stderr: Cow<str>, exit_status: ExitStatus) -> Result<(), Self> {
-        Err(Error::Cli {
+    pub fn cli(message: &str, stdout: Cow<str>, stderr: Cow<str>, exit_status: ExitStatus) -> Self {
+        Error::Cli {
            message: message.to_string(),
+            stdout: stdout.to_string(),
            stderr: stderr.to_string(),
            exit_status,
-        })
+        }
    }

    /// Construct a crate configuration error.
-    pub fn crate_config(message: &str) -> Result<(), Self> {
-        Err(Error::CrateConfig {
+    pub fn crate_config(message: &str) -> Self {
+        Error::CrateConfig {
            message: message.to_string(),
-        })
+        }
    }

    /// Construct an archive error.
@ -161,6 +165,7 @@ impl Error {
            } => "Your rustc version is not supported. Please install version 1.30.0 or higher.",
            Error::Cli {
                message: _,
+                stdout: _,
                stderr: _,
                exit_status: _,
            } => "There was an error while calling another CLI tool. Details:\n\n",
--- a/src/installer.rs
+++ b/src/installer.rs
@ -23,7 +23,7 @@ use std::path::Path;
 use std::process;

 use atty;
-use failure::{Error, ResultExt};
+use failure::{self, ResultExt};
 use which;

 pub fn install() -> ! {
@ -47,7 +47,7 @@ pub fn install() -> ! {
    process::exit(0);
 }

-fn do_install() -> Result<(), Error> {
+fn do_install() -> Result<(), failure::Error> {
    // Find `rustup.exe` in PATH, we'll be using its installation directory as
    // our installation directory.
    let rustup = match which::which("rustup") {
@ -85,7 +85,7 @@ fn do_install() -> Result<(), Error> {
    Ok(())
 }

-fn confirm_can_overwrite(dst: &Path) -> Result<(), Error> {
+fn confirm_can_overwrite(dst: &Path) -> Result<(), failure::Error> {
    // If the `-f` argument was passed, we can always overwrite everything.
    if env::args().any(|arg| arg == "-f") {
        return Ok(());
--- a/src/lib.rs
+++ b/src/lib.rs
@ -29,6 +29,7 @@ extern crate zip;
 pub mod binaries;
 pub mod bindgen;
 pub mod build;
+pub mod child;
 pub mod command;
 pub mod emoji;
 pub mod error;
--- a/src/lockfile.rs
+++ b/src/lockfile.rs
@ -23,10 +23,10 @@ struct Package {

 impl Lockfile {
    /// Read the `Cargo.lock` file for the crate at the given path.
-    pub fn new(crate_path: &Path) -> Result<Lockfile, Error> {
+    pub fn new(crate_path: &Path) -> Result<Lockfile, failure::Error> {
        let lock_path = get_lockfile_path(crate_path)?;
        let lockfile = fs::read_to_string(lock_path)?;
-        toml::from_str(&lockfile).map_err(Error::from)
+        toml::from_str(&lockfile).map_err(|err| Error::from(err).into())
    }

    /// Get the version of `wasm-bindgen` dependency used in the `Cargo.lock`.
@ -36,7 +36,7 @@ impl Lockfile {

    /// Like `wasm_bindgen_version`, except it returns an error instead of
    /// `None`.
-    pub fn require_wasm_bindgen(&self) -> Result<&str, Error> {
+    pub fn require_wasm_bindgen(&self) -> Result<&str, failure::Error> {
        self.wasm_bindgen_version().ok_or_else(|| {
            let message = format!(
                "Ensure that you have \"{}\" as a dependency in your Cargo.toml file:\n\
@ -44,7 +44,7 @@ impl Lockfile {
                 wasm-bindgen = \"0.2\"",
                style("wasm-bindgen").bold().dim(),
            );
-            Error::CrateConfig { message }
+            Error::CrateConfig { message }.into()
        })
    }

@ -63,7 +63,7 @@ impl Lockfile {

 /// Given the path to the crate that we are buliding, return a `PathBuf`
 /// containing the location of the lock file, by finding the workspace root.
-fn get_lockfile_path(crate_path: &Path) -> Result<PathBuf, Error> {
+fn get_lockfile_path(crate_path: &Path) -> Result<PathBuf, failure::Error> {
    // Identify the crate's root directory, or return an error.
    let manifest = crate_path.join("Cargo.toml");
    let crate_root = cargo_metadata::metadata(Some(&manifest))
@ -77,7 +77,8 @@ fn get_lockfile_path(crate_path: &Path) -> Result<PathBuf, Error> {
    if !lockfile_path.is_file() {
        Err(Error::CrateConfig {
            message: format!("Could not find lockfile at {:?}", lockfile_path),
-        })
+        }
+        .into())
    } else {
        Ok(lockfile_path)
    }
--- a/src/logger.rs
+++ b/src/logger.rs
@ -1,7 +1,7 @@
 //! Logging facilities for `wasm-pack`.

 use command::Command;
-use error::Error;
+use failure;
 use slog::{Drain, Level, Logger};
 use slog_async::Async;
 use slog_term::{FullFormat, PlainDecorator};
@ -9,7 +9,7 @@ use std::fs::OpenOptions;
 use std::path::PathBuf;

 /// Create the logger for wasm-pack that will output any info warning or errors we encounter
-pub fn new(cmd: &Command, verbosity: u8) -> Result<Logger, Error> {
+pub fn new(cmd: &Command, verbosity: u8) -> Result<Logger, failure::Error> {
    let log_path = log_file_path(&cmd);
    let file = OpenOptions::new()
        .create(true)
--- a/src/manifest/mod.rs
+++ b/src/manifest/mod.rs
@ -12,6 +12,7 @@ use self::npm::{
 };
 use emoji;
 use error::Error;
+use failure;
 use progressbar::Step;
 use serde_json;
 use toml;
@ -38,22 +39,23 @@ struct CargoPackage {

 impl CargoPackage {
    fn check_optional_fields(&self) {
-        let warn_fmt = |field| {
-            format!(
-                "Field '{}' is missing from Cargo.toml. It is not necessary, but recommended",
-                field
-            )
-        };
-
+        let mut messages = vec![];
        if self.description.is_none() {
-            PBAR.warn(&warn_fmt("description"));
+            messages.push("description");
        }
        if self.repository.is_none() {
-            PBAR.warn(&warn_fmt("repository"));
+            messages.push("repository");
        }
        if self.license.is_none() {
-            PBAR.warn(&warn_fmt("license"));
+            messages.push("license");
        }
+
+        match messages.len() {
+            1 => PBAR.info(&format!("Optional field missing from Cargo.toml: '{}'. This is not necessary, but recommended", messages[0])),
+            2 => PBAR.info(&format!("Optional fields missing from Cargo.toml: '{}', '{}'. These are not necessary, but recommended", messages[0], messages[1])),
+            3 => PBAR.info(&format!("Optional fields missing from Cargo.toml: '{}', '{}', and '{}'. These are not necessary, but recommended", messages[0], messages[1], messages[2])),
+            _ => ()
+        };
    }
 }

@ -75,14 +77,14 @@ struct CargoLib {
    crate_type: Option<Vec<String>>,
 }

-fn read_cargo_toml(path: &Path) -> Result<CargoManifest, Error> {
+fn read_cargo_toml(path: &Path) -> Result<CargoManifest, failure::Error> {
    let manifest_path = path.join("Cargo.toml");
    if !manifest_path.is_file() {
-        return Error::crate_config(&format!(
+        return Err(Error::crate_config(&format!(
            "Crate directory is missing a `Cargo.toml` file; is `{}` the wrong directory?",
            path.display()
        ))
-        .map(|_| unreachable!());
+        .into());
    }
    let mut cargo_file = File::open(manifest_path)?;
    let mut cargo_contents = String::new();
@ -214,7 +216,7 @@ pub fn write_package_json(
    disable_dts: bool,
    target: &str,
    step: &Step,
-) -> Result<(), Error> {
+) -> Result<(), failure::Error> {
    let msg = format!("{}Writing a package.json...", emoji::MEMO);

    PBAR.step(step, &msg);
@ -235,29 +237,29 @@ pub fn write_package_json(
 }

 /// Get the crate name for the crate at the given path.
-pub fn get_crate_name(path: &Path) -> Result<String, Error> {
+pub fn get_crate_name(path: &Path) -> Result<String, failure::Error> {
    Ok(read_cargo_toml(path)?.package.name)
 }

 /// Check that the crate the given path is properly configured.
-pub fn check_crate_config(path: &Path, step: &Step) -> Result<(), Error> {
+pub fn check_crate_config(path: &Path, step: &Step) -> Result<(), failure::Error> {
    let msg = format!("{}Checking crate configuration...", emoji::WRENCH);
    PBAR.step(&step, &msg);
    check_crate_type(path)?;
    Ok(())
 }

-fn check_crate_type(path: &Path) -> Result<(), Error> {
+fn check_crate_type(path: &Path) -> Result<(), failure::Error> {
    if read_cargo_toml(path)?.lib.map_or(false, |lib| {
        lib.crate_type
            .map_or(false, |types| types.iter().any(|s| s == "cdylib"))
    }) {
        return Ok(());
    }
-    Error::crate_config(
+    Err(Error::crate_config(
      "crate-type must be cdylib to compile to wasm32-unknown-unknown. Add the following to your \
       Cargo.toml file:\n\n\
       [lib]\n\
       crate-type = [\"cdylib\", \"rlib\"]"
-    )
+    ).into())
 }
--- a/src/npm.rs
+++ b/src/npm.rs
@ -1,56 +1,51 @@
 //! Functionality related to publishing to npm.

+use child;
 use command::publish::access::Access;
-use error::Error;
+use failure::{self, ResultExt};
+use slog::Logger;
 use std::process::{Command, Stdio};

 /// The default npm registry used when we aren't working with a custom registry.
 pub const DEFAULT_NPM_REGISTRY: &'static str = "https://registry.npmjs.org/";

 /// Run the `npm pack` command.
-pub fn npm_pack(path: &str) -> Result<(), Error> {
-    let output = Command::new("npm").current_dir(path).arg("pack").output()?;
-    if !output.status.success() {
-        let s = String::from_utf8_lossy(&output.stderr);
-        Error::cli("Packaging up your code failed", s, output.status)
-    } else {
-        Ok(())
-    }
+pub fn npm_pack(log: &Logger, path: &str) -> Result<(), failure::Error> {
+    let mut cmd = Command::new("npm");
+    cmd.current_dir(path).arg("pack");
+    child::run(log, cmd, "npm pack").context("Packaging up your code failed")?;
+    Ok(())
 }

 /// Run the `npm publish` command.
-pub fn npm_publish(path: &str, access: Option<Access>) -> Result<(), Error> {
-    let output = match access {
-        Some(a) => Command::new("npm")
+pub fn npm_publish(log: &Logger, path: &str, access: Option<Access>) -> Result<(), failure::Error> {
+    let mut cmd = Command::new("npm");
+    match access {
+        Some(a) => cmd
            .current_dir(path)
            .arg("publish")
            .arg(&format!("{}", a.to_string()))
            .stdin(Stdio::inherit())
-            .stdout(Stdio::inherit())
-            .output()?,
-        None => Command::new("npm")
+            .stdout(Stdio::inherit()),
+        None => cmd
            .current_dir(path)
            .arg("publish")
            .stdin(Stdio::inherit())
-            .stdout(Stdio::inherit())
-            .output()?,
+            .stdout(Stdio::inherit()),
    };

-    if !output.status.success() {
-        let s = String::from_utf8_lossy(&output.stderr);
-        Error::cli("Publishing to npm failed", s, output.status)
-    } else {
-        Ok(())
-    }
+    child::run(log, cmd, "npm publish").context("Publishing to npm failed")?;
+    Ok(())
 }

 /// Run the `npm login` command.
 pub fn npm_login(
+    log: &Logger,
    registry: &String,
    scope: &Option<String>,
    always_auth: bool,
    auth_type: &Option<String>,
-) -> Result<(), Error> {
+) -> Result<(), failure::Error> {
    let mut args = String::new();

    args.push_str(&format!("--registry={}", registry));
@ -67,21 +62,12 @@ pub fn npm_login(
        args.push_str(&format!(" --auth_type={}", auth_type));
    }

-    let output = Command::new("npm")
-        .arg("login")
+    let mut cmd = Command::new("npm");
+    cmd.arg("login")
        .arg(args)
        .stdin(Stdio::inherit())
-        .stdout(Stdio::inherit())
-        .output()?;
-
-    if !output.status.success() {
-        let s = String::from_utf8_lossy(&output.stderr);
-        Error::cli(
-            &format!("Login to registry {} failed", registry),
-            s,
-            output.status,
-        )
-    } else {
-        Ok(())
-    }
+        .stdout(Stdio::inherit());
+    child::run(log, cmd, "npm login")
+        .with_context(|_| format!("Login to registry {} failed", registry))?;
+    Ok(())
 }
--- a/src/readme.rs
+++ b/src/readme.rs
@ -1,6 +1,6 @@
 //! Generating `README` files for the packaged wasm.

-use error::Error;
+use failure;
 use std::fs;
 use std::path::Path;

@ -9,7 +9,7 @@ use progressbar::Step;
 use PBAR;

 /// Copy the crate's README into the `pkg` directory.
-pub fn copy_from_crate(path: &Path, out_dir: &Path, step: &Step) -> Result<(), Error> {
+pub fn copy_from_crate(path: &Path, out_dir: &Path, step: &Step) -> Result<(), failure::Error> {
    assert!(
        fs::metadata(path).ok().map_or(false, |m| m.is_dir()),
        "crate directory should exist"
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@ -2,7 +2,8 @@

 pub mod webdriver;

-use error::Error;
+use child;
+use failure::{self, ResultExt};
 use slog::Logger;
 use std::ffi::OsStr;
 use std::path::Path;
@ -15,7 +16,7 @@ pub fn cargo_test_wasm<I, K, V>(
    release: bool,
    log: &Logger,
    envs: I,
-) -> Result<(), Error>
+) -> Result<(), failure::Error>
 where
    I: IntoIterator<Item = (K, V)>,
    K: AsRef<OsStr>,
@ -35,17 +36,13 @@ where
            cmd.arg("--release");
        }
        cmd.arg("--target").arg("wasm32-unknown-unknown");
-        cmd.output()?
+        child::run(log, cmd, "cargo test")
+            .context("Running Wasm tests with wasm-bindgen-test failed")?
    };

-    if !output.status.success() {
-        let s = String::from_utf8_lossy(&output.stderr);
-        Error::cli("Running wasm tests failed", s, output.status)
-    } else {
-        for line in String::from_utf8_lossy(&output.stdout).lines() {
-            info!(log, "test output: {}", line);
-            println!("{}", line);
-        }
-        Ok(())
+    for line in output.lines() {
+        info!(log, "test output: {}", line);
+        println!("{}", line);
    }
+    Ok(())
 }
--- a/src/test/webdriver.rs
+++ b/src/test/webdriver.rs
@ -5,6 +5,7 @@ use binaries::{
 };
 use command::build::BuildMode;
 use error::Error;
+use failure;
 use slog::Logger;
 use std::path::{Path, PathBuf};
 use target;
@ -15,17 +16,17 @@ pub fn get_or_install_chromedriver(
    log: &Logger,
    crate_path: &Path,
    mode: BuildMode,
-) -> Result<PathBuf, Error> {
+) -> Result<PathBuf, failure::Error> {
    match (mode, bin_path(log, crate_path, "chromedriver")) {
        (_, Some(path)) => Ok(path),
        (BuildMode::Normal, None) => install_chromedriver(crate_path),
        (BuildMode::Force, None) => install_chromedriver(crate_path),
-        (BuildMode::Noinstall, None) => Error::crate_config(
+        (BuildMode::Noinstall, None) => Err(Error::crate_config(
            "No crate-local `chromedriver` binary found, and could not find a global \
             `chromedriver` on the `$PATH`. Not installing `chromedriver` because of noinstall \
             mode.",
        )
-        .map(|_| unreachable!()),
+        .into()),
    }
 }

@ -53,7 +54,7 @@ fn get_chromedriver_url() -> Result<String, Error> {
 }

 /// Download and install a pre-built `chromedriver` binary.
-pub fn install_chromedriver(crate_path: &Path) -> Result<PathBuf, Error> {
+pub fn install_chromedriver(crate_path: &Path) -> Result<PathBuf, failure::Error> {
    let url = get_chromedriver_url()?;
    install_binaries_from_zip_at_url(crate_path, &url, Some("chromedriver"))?;
    let chromedriver = get_local_chromedriver_path(crate_path);
@ -67,16 +68,16 @@ pub fn get_or_install_geckodriver(
    log: &Logger,
    crate_path: &Path,
    mode: BuildMode,
-) -> Result<PathBuf, Error> {
+) -> Result<PathBuf, failure::Error> {
    match (mode, bin_path(log, crate_path, "geckodriver")) {
        (_, Some(path)) => Ok(path),
        (BuildMode::Normal, None) => install_geckodriver(crate_path),
        (BuildMode::Force, None) => install_geckodriver(crate_path),
-        (BuildMode::Noinstall, None) => Error::crate_config(
+        (BuildMode::Noinstall, None) => Err(Error::crate_config(
            "No crate-local `geckodriver` binary found, and could not find a global `geckodriver` \
             on the `$PATH`. Not installing `geckodriver` because of noinstall mode.",
        )
-        .map(|_| unreachable!()),
+        .into()),
    }
 }

@ -109,7 +110,7 @@ fn get_local_geckodriver_path(crate_path: &Path) -> PathBuf {
 }

 /// Download and install a pre-built `geckodriver` binary.
-pub fn install_geckodriver(crate_path: &Path) -> Result<PathBuf, Error> {
+pub fn install_geckodriver(crate_path: &Path) -> Result<PathBuf, failure::Error> {
    let url = get_geckodriver_url()?;

    if url.ends_with("tar.gz") {
@ -133,6 +134,8 @@ pub fn get_safaridriver(log: &Logger, crate_path: &Path) -> Result<PathBuf, Erro
    if let Some(p) = bin_path(log, crate_path, "safaridriver") {
        Ok(p)
    } else {
-        Error::crate_config("could not find `safaridriver` on the `$PATH`").map(|_| unreachable!())
+        Err(Error::crate_config(
+            "could not find `safaridriver` on the `$PATH`",
+        ))
    }
 }
--- a/tests/all/main.rs
+++ b/tests/all/main.rs
@ -2,6 +2,8 @@ extern crate failure;
 #[macro_use]
 extern crate serde_derive;
 extern crate serde_json;
+#[macro_use]
+extern crate slog;
 extern crate structopt;
 extern crate tempfile;
 extern crate wasm_pack;
--- a/tests/all/utils/fixture.rs
+++ b/tests/all/utils/fixture.rs
@ -1,3 +1,4 @@
+use super::logger::null_logger;
 use std::env;
 use std::fs;
 use std::io;
@ -6,9 +7,8 @@ use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
 use std::sync::{Once, ONCE_INIT};
 use std::thread;
-use wasm_pack;
-
 use tempfile::TempDir;
+use wasm_pack;

 fn hard_link_or_copy<P1: AsRef<Path>, P2: AsRef<Path>>(from: P1, to: P2) -> io::Result<()> {
    let from = from.as_ref();
@ -151,7 +151,11 @@ impl Fixture {
            const WASM_BINDGEN_VERSION: &str = "0.2.21";
            wasm_pack::bindgen::download_prebuilt_wasm_bindgen(&tests, WASM_BINDGEN_VERSION)
                .or_else(|_| {
-                    wasm_pack::bindgen::cargo_install_wasm_bindgen(&tests, WASM_BINDGEN_VERSION)
+                    wasm_pack::bindgen::cargo_install_wasm_bindgen(
+                        &null_logger(),
+                        &tests,
+                        WASM_BINDGEN_VERSION,
+                    )
                })
                .unwrap();
        });
--- a/tests/all/utils/logger.rs
+++ b/tests/all/utils/logger.rs
@ -0,0 +1,6 @@
+use slog::Logger;
+
+// Create a logger that ignores log messages for testing.
+pub fn null_logger() -> Logger {
+    Logger::root(slog::Discard, o!())
+}
--- a/tests/all/utils/mod.rs
+++ b/tests/all/utils/mod.rs
@ -1,3 +1,4 @@
 pub mod file;
 pub mod fixture;
+pub mod logger;
 pub mod manifest;