builder: retain Cargo config for run and correct acceptance checks

host/tests/builder.rs

@@ -171,7 +171,8 @@ async fn cargo_build_test_and_source_changes() -> anyhow::Result<()> {
     .await?;
     assert_eq!(code, 0, "{out}");
     assert!(out.contains("INTEGRATION_CASE"), "{out}");
-    let (code, out) = cargo(&runtime, &["test", "fail"]).await?;
+    // WASI aborts on panic, so disable capture to expose the panic message.
+    let (code, out) = cargo(&runtime, &["test", "fail", "--", "--nocapture"]).await?;
     assert_eq!(code, 101, "{out}");
     assert!(out.contains("intentional fixture failure"), "{out}");
     let (code, out) = cargo(&runtime, &["test", "--no-run"]).await?;
@@ -291,7 +292,7 @@ async fn timeout_and_cancellation() -> anyhow::Result<()> {
     std::fs::create_dir_all(&bin)?;
     std::fs::copy(binaries.join("cargo.wasm"), bin.join("cargo.wasm"))?;
     let runtime = Runtime::new(world)?;
-    let code = runtime
+    let error = runtime
         .exec(
             Command::Argv(vec!["/bin/cargo.wasm".into(), "build".into()]),
             Options {
@@ -301,10 +302,11 @@ async fn timeout_and_cancellation() -> anyhow::Result<()> {
             },
             &mut |_, _| {},
         )
-        .await?;
-    assert_ne!(code, 0);
+        .await
+        .unwrap_err();
+    assert!(error.to_string().contains("timed out"), "{error}");
     let (code, out) =
-        tokio::time::timeout(Duration::from_secs(5), cargo(&runtime, &["metadata"])).await??;
+        tokio::time::timeout(Duration::from_secs(20), cargo(&runtime, &["metadata"])).await??;
     assert_eq!(
         code, 0,
         "the canceled build still held the builder lock: {out}"