cmd/test2json: do not emit a final Action if the result is not known

If we are parsing a test output, and the test does not end in the
usual PASS or FAIL line (say, because it panicked), then we need the
exit status of the test binary in order to determine whether the test
passed or failed. If we don't have that status available, we shouldn't
guess arbitrarily — instead, we should omit the final "pass" or "fail"
action entirely.

(In practice, we nearly always DO have the final status, such as when
running 'go test' or 'go tool test2json some.exe'.)

Fixes #40132

Change-Id: Iae482577361a6033395fe4a05d746b980e18c3de
Reviewed-on: https://go-review.googlesource.com/c/go/+/248624
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index 9c120e08dc..9cef8cf89c 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -1098,9 +1098,13 @@ func (c *runCache) builderRunTest(b *work.Builder, ctx context.Context, a *work.
 	}
 
 	var stdout io.Writer = os.Stdout
+	var err error
 	if testJSON {
 		json := test2json.NewConverter(lockedStdout{}, a.Package.ImportPath, test2json.Timestamp)
-		defer json.Close()
+		defer func() {
+			json.Exited(err)
+			json.Close()
+		}()
 		stdout = json
 	}
 
@@ -1204,7 +1208,7 @@ func (c *runCache) builderRunTest(b *work.Builder, ctx context.Context, a *work.
 	}
 
 	t0 := time.Now()
-	err := cmd.Start()
+	err = cmd.Start()
 
 	// This is a last-ditch deadline to detect and
 	// stop wedged test binaries, to keep the builders