Fix tests on Rust nightly

The build directory layout of Cargo is changing so this updates the
build/run of Rust tests to read the JSON messages from Cargo about where
artifacts are located.

Author: alexcrichton

Cargo.lock

@@ -40,6 +40,7 @@ bitflags = "2.11.1"
 heck = { version = "0.5" }
 pulldown-cmark = { version = "0.13.3", default-features = false }
 serde = { version = "1.0.228", features = ["derive"] }
+serde_json = { version = "1" }
 clap = { version = "4.6.1", features = ["derive"] }
 indexmap = "2.0.0"
 prettyplease = "0.2.20"

Cargo.toml

@@ -39,7 +39,7 @@ futures = { workspace = true }
 wit-bindgen = { path = '../guest-rust', features = ['async'] }
 test-helpers = { path = '../test-helpers' }
 # For use with the custom attributes test
-serde_json = "1"
+serde_json = { workspace = true }
 bytes = "1"
 
 [features]

crates/rust/Cargo.toml

@@ -25,6 +25,7 @@ heck = { workspace = true }
 log = "0.4.26"
 regex = "1.11.1"
 serde = { workspace = true }
+serde_json = { workspace = true }
 toml = "1.1.2"
 wasi-preview1-component-adapter-provider = "46.0.1"
 wac-parser = "0.10.0"

crates/test/Cargo.toml

@@ -187,5 +187,6 @@ fn verify(runner: &Runner, verify: &Verify<'_>, compiler: PathBuf) -> Result<()>
     .arg("-c")
     .arg("-o")
     .arg(verify.artifacts_dir.join("tmp.o"));
-    runner.run_command(&mut cmd)
+    runner.run_command(&mut cmd)?;
+    Ok(())
 }

crates/test/src/c.rs

@@ -207,6 +207,7 @@ impl LanguageMethods for Cpp {
         .arg("-c")
         .arg("-o")
         .arg(verify.artifacts_dir.join("tmp.o"));
-        runner.run_command(&mut cmd)
+        runner.run_command(&mut cmd)?;
+        Ok(())
     }
 }

crates/test/src/cpp.rs

@@ -144,6 +144,7 @@ impl LanguageMethods for Csharp {
             .arg(&wasm_filename);
         runner.run_command(&mut cmd)?;
 
-        runner.run_command(dotnet().current_dir(&dir).arg("clean"))
+        runner.run_command(dotnet().current_dir(&dir).arg("clean"))?;
+        Ok(())
     }
 }

crates/test/src/csharp.rs

@@ -115,7 +115,8 @@ impl LanguageMethods for Language {
                 .arg("bindgen")
                 .env("WIT", &bindgen.wit_path)
                 .env("BINDINGS_DIR", dir),
-        )
+        )?;
+        Ok(())
     }
 
     fn prepare(&self, runner: &mut Runner) -> Result<()> {
@@ -126,7 +127,8 @@ impl LanguageMethods for Language {
             Command::new(&self.script)
                 .arg("prepare")
                 .env("PREP_DIR", &dir),
-        )
+        )?;
+        Ok(())
     }
 
     fn compile(&self, runner: &Runner, compile: &Compile<'_>) -> Result<()> {
@@ -142,7 +144,8 @@ impl LanguageMethods for Language {
                 .env("BINDINGS_DIR", &compile.bindings_dir)
                 .env("ARTIFACTS_DIR", &compile.artifacts_dir)
                 .env("OUTPUT", &compile.output),
-        )
+        )?;
+        Ok(())
     }
 
     fn verify(&self, runner: &Runner, verify: &Verify<'_>) -> Result<()> {
@@ -152,6 +155,7 @@ impl LanguageMethods for Language {
                 .env("WIT", verify.wit_test)
                 .env("BINDINGS_DIR", &verify.bindings_dir)
                 .env("ARTIFACTS_DIR", &verify.artifacts_dir),
-        )
+        )?;
+        Ok(())
     }
 }

crates/test/src/custom.rs

@@ -190,7 +190,8 @@ func main() {}
                 .arg(verify.artifacts_dir.join("tmp.wasm"))
                 .arg("-buildmode=c-shared")
                 .arg("-ldflags=-checklinkname=0"),
-        )
+        )?;
+        Ok(())
     }
 }
 

crates/test/src/go.rs

@@ -1049,15 +1049,15 @@ impl Runner {
 
     /// Helper to execute an external process and generate a helpful error
     /// message on failure.
-    fn run_command(&self, cmd: &mut Command) -> Result<()> {
+    fn run_command(&self, cmd: &mut Command) -> Result<String> {
         if self.opts.inherit_stderr {
             cmd.stderr(Stdio::inherit());
         }
         let output = cmd
             .output()
             .with_context(|| format!("failed to spawn {cmd:?}"))?;
         if output.status.success() {
-            return Ok(());
+            return Ok(String::from_utf8_lossy(&output.stdout).into());
         }
 
         let mut error = format!(
@@ -1256,7 +1256,8 @@ trait LanguageMethods {
             cmd.arg(arg);
         }
 
-        runner.run_command(&mut cmd)
+        runner.run_command(&mut cmd)?;
+        Ok(())
     }
 
     /// Returns the default set of arguments that will be passed to