cmd/go: fix -x output for test build failure

If the build of the test binary failed, the go command correctly
avoided running the binary, but the -x output indicated otherwise.

Fixes #22659.

Change-Id: Ib4d262bf1735f057c994a45fc23c499d4ebe3246
Reviewed-on: https://go-review.googlesource.com/81495
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/go/go_test.go

@@ -2469,6 +2469,17 @@ func TestCoverageErrorLine(t *testing.T) {
 	}
 }
 
+func TestTestBuildFailureOutput(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
+
+	// Doesn't build, -x output should not claim to run test.
+	tg.runFail("test", "-x", "coverbad")
+	tg.grepStderrNot(`[\\/]coverbad\.test( |$)`, "claimed to run test")
+}
+
 func TestCoverageFunc(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()

src/cmd/go/internal/test/test.go

@@ -1238,14 +1238,6 @@ func (c *runCache) builderRunTest(b *work.Builder, a *work.Action) error {
 		return nil
 	}
 
-	args := str.StringList(work.FindExecCmd(), a.Deps[0].Target, testArgs)
-	if cfg.BuildN || cfg.BuildX {
-		b.Showcmd("", "%s", strings.Join(args, " "))
-		if cfg.BuildN {
-			return nil
-		}
-	}
-
 	if a.Failed {
 		// We were unable to build the binary.
 		a.Failed = false
@@ -1255,6 +1247,8 @@ func (c *runCache) builderRunTest(b *work.Builder, a *work.Action) error {
 		return nil
 	}
 
+	args := str.StringList(work.FindExecCmd(), a.Deps[0].Target, testArgs)
+
 	if testCoverProfile != "" {
 		// Write coverage to temporary profile, for merging later.
 		for i, arg := range args {
@@ -1264,6 +1258,13 @@ func (c *runCache) builderRunTest(b *work.Builder, a *work.Action) error {
 		}
 	}
 
+	if cfg.BuildN || cfg.BuildX {
+		b.Showcmd("", "%s", strings.Join(args, " "))
+		if cfg.BuildN {
+			return nil
+		}
+	}
+
 	cmd := exec.Command(args[0], args[1:]...)
 	cmd.Dir = a.Package.Dir
 	cmd.Env = base.EnvForDir(cmd.Dir, cfg.OrigEnv)