test: support non-host tests

For example, for running tests with -target=wasm or
-target=cortex-m-qemu. It looks at the output to determine whether tests
were successful in the absence of a status code.

main.go

@@ -128,22 +128,50 @@ func Test(pkgName string, options *compileopts.Options) error {
 	}
 
 	return builder.Build(pkgName, ".elf", config, func(result builder.BuildResult) error {
-		cmd := exec.Command(result.Binary)
-		cmd.Stdout = os.Stdout
-		cmd.Stderr = os.Stderr
-		cmd.Dir = result.MainDir
-		err := cmd.Run()
-		if err != nil {
-			// Propagate the exit code
-			if err, ok := err.(*exec.ExitError); ok {
-				if status, ok := err.Sys().(syscall.WaitStatus); ok {
-					os.Exit(status.ExitStatus())
+		if len(config.Target.Emulator) == 0 {
+			// Run directly.
+			cmd := exec.Command(result.Binary)
+			cmd.Stdout = os.Stdout
+			cmd.Stderr = os.Stderr
+			cmd.Dir = result.MainDir
+			err := cmd.Run()
+			if err != nil {
+				// Propagate the exit code
+				if err, ok := err.(*exec.ExitError); ok {
+					if status, ok := err.Sys().(syscall.WaitStatus); ok {
+						os.Exit(status.ExitStatus())
+					}
+					os.Exit(1)
 				}
-				os.Exit(1)
+				return &commandError{"failed to run compiled binary", result.Binary, err}
+			}
+			return nil
+		} else {
+			// Run in an emulator.
+			args := append(config.Target.Emulator[1:], result.Binary)
+			cmd := exec.Command(config.Target.Emulator[0], args...)
+			buf := &bytes.Buffer{}
+			w := io.MultiWriter(os.Stdout, buf)
+			cmd.Stdout = w
+			cmd.Stderr = os.Stderr
+			err := cmd.Run()
+			if err != nil {
+				if err, ok := err.(*exec.ExitError); !ok || !err.Exited() {
+					// Workaround for QEMU which always exits with an error.
+					return &commandError{"failed to run emulator with", result.Binary, err}
+				}
+			}
+			testOutput := string(buf.Bytes())
+			if testOutput == "PASS\n" || strings.HasSuffix(testOutput, "\nPASS\n") {
+				// Test passed.
+				return nil
+			} else {
+				// Test failed, either by ending with the word "FAIL" or with a
+				// panic of some sort.
+				os.Exit(1)
+				return nil // unreachable
 			}
-			return &commandError{"failed to run compiled binary", result.Binary, err}
 		}
-		return nil
 	})
 }
 

src/runtime/baremetal.go

@@ -39,4 +39,9 @@ func libc_free(ptr unsafe.Pointer) {
 	free(ptr)
 }
 
+//go:linkname syscall_Exit syscall.Exit
+func syscall_Exit(code int) {
+	abort()
+}
+
 const baremetal = true

src/runtime/runtime_cortexm_abort.go

@@ -1,4 +1,4 @@
-// +build cortexm,!nxp
+// +build cortexm,!nxp,!qemu
 
 package runtime
 

src/runtime/runtime_cortexm_qemu.go

@@ -21,6 +21,8 @@ func postinit() {}
 func main() {
 	preinit()
 	run()
+
+	// Signal successful exit.
 	arm.SemihostingCall(arm.SemihostingReportException, arm.SemihostingApplicationExit)
 	abort()
 }
@@ -54,3 +56,13 @@ func putchar(c byte) {
 func waitForEvents() {
 	arm.Asm("wfe")
 }
+
+func abort() {
+	// Signal an abnormal exit.
+	arm.SemihostingCall(arm.SemihostingReportException, arm.SemihostingRunTimeErrorUnknown)
+
+	// Lock up forever (should be unreachable).
+	for {
+		arm.Asm("wfi")
+	}
+}

src/testing/testing.go

@@ -195,6 +195,8 @@ func (m *M) Run() int {
 	if failures > 0 {
 		fmt.Printf("exit status %d\n", failures)
 		fmt.Println("FAIL")
+	} else {
+		fmt.Println("PASS")
 	}
 	return failures
 }

targets/wasm_exec.js

@@ -289,6 +289,17 @@
 						setTimeout(this._inst.exports.go_scheduler, timeout);
 					},
 
+					// func Exit(code int)
+					"syscall.Exit": (code) => {
+						if (global.process) {
+							// Node.js
+							process.exit(code);
+						} else {
+							// Can't exit in a browser.
+							throw 'trying to exit with code ' + code;
+						}
+					},
+
 					// func finalizeRef(v ref)
 					"syscall/js.finalizeRef": (sp) => {
 						// Note: TinyGo does not support finalizers so this should never be