Fix panics in `build --mode no-install`

This commit fixes the `wasm-pack build --mode no-install` command from
unconditionally panicking as well as `--mode force`. These steps were
calling an `unwrap()` on an internal `Option<T>` which was supposed to
be set during `step_install_wasm_bindgen`, but that step wasn't run in
these modes. The mode configuration of steps has been refactored
slightly to ensure that more steps are shared between these modes to
reduce duplication.

src/command/build.rs

@@ -259,38 +259,27 @@ impl Build {
                 };
             ($($name:ident,)*) => (steps![$($name),*])
         }
+        let mut steps = Vec::new();
         match &mode {
-            BuildMode::Normal => steps![
-                step_check_rustc_version,
-                step_check_crate_config,
-                step_check_for_wasm_target,
-                step_build_wasm,
-                step_create_dir,
-                step_copy_readme,
-                step_copy_license,
-                step_install_wasm_bindgen,
-                step_run_wasm_bindgen,
-                step_create_json,
-            ],
-            BuildMode::Noinstall => steps![
-                step_check_rustc_version,
-                step_check_crate_config,
-                step_build_wasm,
-                step_create_dir,
-                step_copy_readme,
-                step_copy_license,
-                step_run_wasm_bindgen,
-                step_create_json,
-            ],
-            BuildMode::Force => steps![
-                step_build_wasm,
-                step_create_dir,
-                step_copy_readme,
-                step_copy_license,
-                step_run_wasm_bindgen,
-                step_create_json,
-            ],
+            BuildMode::Force => {}
+            _ => {
+                steps.extend(steps![
+                    step_check_rustc_version,
+                    step_check_crate_config,
+                    step_check_for_wasm_target,
+                ]);
+            }
         }
+        steps.extend(steps![
+            step_build_wasm,
+            step_create_dir,
+            step_copy_readme,
+            step_copy_license,
+            step_install_wasm_bindgen,
+            step_run_wasm_bindgen,
+            step_create_json,
+        ]);
+        steps
     }
 
     fn step_check_rustc_version(&mut self) -> Result<(), Error> {

tests/all/build.rs

@@ -212,3 +212,29 @@ fn build_with_arbitrary_cargo_options() {
         .assert()
         .success();
 }
+
+#[test]
+fn build_no_install() {
+    let fixture = utils::fixture::js_hello_world();
+    fixture.install_local_wasm_bindgen();
+    fixture
+        .wasm_pack()
+        .arg("build")
+        .arg("--mode")
+        .arg("no-install")
+        .assert()
+        .success();
+}
+
+#[test]
+fn build_force() {
+    let fixture = utils::fixture::js_hello_world();
+    fixture.install_local_wasm_bindgen();
+    fixture
+        .wasm_pack()
+        .arg("build")
+        .arg("--mode")
+        .arg("force")
+        .assert()
+        .success();
+}