cmd/go: print finally FAIL if a test has failed in package list mode

Fixes golang#30507

Change-Id: Ic598e4d5f71c624fcde051982bf85533e2f18e8d

src/cmd/go/internal/base/base.go

@@ -132,6 +132,10 @@ func SetExitStatus(n int) {
 	exitMu.Unlock()
 }
 
+func GetExitStatus() int {
+	return exitStatus
+}
+
 // Run runs the command, with stdout and stderr
 // connected to the go command's own stdout and stderr.
 // If the command fails, Run reports the error using Errorf.

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

@@ -102,7 +102,10 @@ package test passes, go test prints only the final 'ok' summary
 line. If a package test fails, go test prints the full test output.
 If invoked with the -bench or -v flag, go test prints the full
 output even for passing package tests, in order to display the
-requested benchmark results or verbose logging.
+requested benchmark results or verbose logging. After the package
+tests for all of the listed packages finish, and their output is
+printed, go test prints a final 'FAIL' status if any package test
+has failed.
 
 In package list mode only, go test caches successful package test
 results to avoid unnecessary repeated running of tests. When the
@@ -726,7 +729,7 @@ func runTest(cmd *base.Command, args []string) {
 	}
 
 	// Ultimately the goal is to print the output.
-	root := &work.Action{Mode: "go test", Deps: prints}
+	root := &work.Action{Mode: "go test", Func: printExitStatus, Deps: prints}
 
 	// Force the printing of results to happen in order,
 	// one at a time.
@@ -1623,3 +1626,14 @@ func builderNoTest(b *work.Builder, a *work.Action) error {
 	fmt.Fprintf(stdout, "?   \t%s\t[no test files]\n", a.Package.ImportPath)
 	return nil
 }
+
+// printExitStatus is the action for printing the exit status
+func printExitStatus(b *work.Builder, a *work.Action) error {
+	if !testJSON && len(pkgArgs) != 0 {
+		if base.GetExitStatus() != 0 {
+			fmt.Println("FAIL")
+			return nil
+		}
+	}
+	return nil
+}

src/cmd/go/testdata/script/test_status.txt

@@ -0,0 +1,18 @@
+env GO111MODULE=off
+
+! go test x y
+stdout ^FAIL\s+x
+stdout ^ok\s+y
+stdout (?-m)FAIL\n$
+
+-- x/x_test.go --
+package x
+
+import "testing"
+
+func TestNothingJustFail(t *testing.T) {
+    t.Fail()
+}
+
+-- y/y_test.go --
+package y