Add back building tests

src/build.rs

@@ -25,7 +25,7 @@ pub fn check_rustc_version(step: &Step) -> Result<String, Error> {
             } else {
                 Ok(mv.to_string())
             }
-        },
+        }
         None => bail!("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."),
     }
 }
@@ -93,3 +93,18 @@ pub fn cargo_build_wasm(
     child::run(cmd, "cargo build").context("Compiling your crate to WebAssembly failed")?;
     Ok(())
 }
+
+/// Run `cargo build --tests` targetting `wasm32-unknown-unknown`.
+///
+/// This generates the `Cargo.lock` file that we use in order to know which version of
+/// wasm-bindgen-cli to use when running tests.
+pub fn cargo_build_wasm_tests(path: &Path, debug: bool) -> Result<(), 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(cmd, "cargo build").context("Compilation of your program failed")?;
+    Ok(())
+}

src/command/test.rs

@@ -197,6 +197,7 @@ impl Test {
             BuildMode::Normal => steps![
                 step_check_rustc_version,
                 step_add_wasm_target,
+                                step_build_tests,
                 step_install_wasm_bindgen,
                 step_test_node if self.node,
                 step_get_chromedriver if self.chrome && self.chromedriver.is_none(),
@@ -208,6 +209,7 @@ impl Test {
             ],
             BuildMode::Force => steps![
                 step_add_wasm_target,
+                step_build_tests,
                 step_install_wasm_bindgen,
                 step_test_node if self.node,
                 step_get_chromedriver if self.chrome && self.chromedriver.is_none(),
@@ -218,6 +220,7 @@ impl Test {
                 step_test_safari if self.safari,
             ],
             BuildMode::Noinstall => steps![
+            step_build_tests,
                 step_install_wasm_bindgen,
                 step_test_node if self.node,
                 step_get_chromedriver if self.chrome && self.chromedriver.is_none(),
@@ -244,6 +247,18 @@ impl Test {
         Ok(())
     }
 
+    fn step_build_tests(&mut self, step: &Step) -> Result<(), Error> {
+        info!("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)?;
+
+        info!("Finished compiling tests to wasm.");
+        Ok(())
+    }
+
     fn step_install_wasm_bindgen(&mut self, step: &Step) -> Result<(), Error> {
         info!("Identifying wasm-bindgen dependency...");
         let lockfile = Lockfile::new(&self.crate_data)?;