cmd/go: ensure that 'go test' prints the FAIL line for a package on a new line

Fixes #49317

Change-Id: I4038fd4c1d845d54ecbbf82bf73060db1b44c9bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/361095
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index de6525d541cef0c28ffcc905e9b6bab0a9f24206..7361c11786e04ea5e896457bc7c9a7fd02c18566 100644 (file)
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -1405,15 +1405,25 @@ func (c *runCache) builderRunTest(b *work.Builder, ctx context.Context, a *work.
                if bytes.HasPrefix(out, tooManyTargetsToFuzz[1:]) || bytes.Contains(out, tooManyTargetsToFuzz) {
                        norun = " [will not fuzz, -fuzz matches more than one target]"
                }
+               if len(out) > 0 && !bytes.HasSuffix(out, []byte("\n")) {
+                       // Ensure that the output ends with a newline before the "ok"
+                       // line we're about to print (https://golang.org/issue/49317).
+                       cmd.Stdout.Write([]byte("\n"))
+               }
                fmt.Fprintf(cmd.Stdout, "ok  \t%s\t%s%s%s\n", a.Package.ImportPath, t, coveragePercentage(out), norun)
                c.saveOutput(a)
        } else {
                base.SetExitStatus(1)
-               // If there was test output, assume we don't need to print the exit status.
-               // Buf there's no test output, do print the exit status.
                if len(out) == 0 {
+                       // If there was no test output, print the exit status so that the reason
+                       // for failure is clear.
                        fmt.Fprintf(cmd.Stdout, "%s\n", err)
+               } else if !bytes.HasSuffix(out, []byte("\n")) {
+                       // Otherwise, ensure that the output ends with a newline before the FAIL
+                       // line we're about to print (https://golang.org/issue/49317).
+                       cmd.Stdout.Write([]byte("\n"))
                }
+
                // NOTE(golang.org/issue/37555): test2json reports that a test passes
                // unless "FAIL" is printed at the beginning of a line. The test may not
                // actually print that if it panics, exits, or terminates abnormally,

diff --git a/src/cmd/go/testdata/script/test_fail_newline.txt b/src/cmd/go/testdata/script/test_fail_newline.txt
new file mode 100644 (file)
index 0000000..43cee56
--- /dev/null
+++ b/src/cmd/go/testdata/script/test_fail_newline.txt
@@ -0,0 +1,65 @@
+[short] skip
+
+# In package list mode, output is buffered.
+# Check that a newline is printed after the buffer's contents.
+cd fail
+! go test .
+! stderr .
+stdout '^exitcode=1\n'
+stdout '^FAIL\s+example/fail'
+
+# In local directory mode output is streamed, so we don't know
+# whether the test printed anything at all, so we print the exit code
+# (just in case it failed without emitting any output at all),
+# and that happens to add the needed newline as well.
+! go test
+! stderr .
+stdout '^exitcode=1exit status 1\n'
+stdout '^FAIL\s+example/fail'
+
+# In package list mode, if the test passes the 'ok' message appears
+# on its own line.
+cd ../skip
+go test -v .
+! stderr .
+stdout '^skipping\n'
+stdout '^ok\s+example/skip'
+
+# If the output is streamed and the test passes, we can't tell whether it ended
+# in a partial line, and don't want to emit any extra output in the
+# overwhelmingly common case that it did not.
+# (In theory we could hook the 'os' package to report whether output
+# was emitted and whether it ended in a newline, but that seems too invasive.)
+go test
+! stderr .
+stdout '^skippingok\s+example/skip'
+
+
+-- go.mod --
+module example
+
+go 1.18
+-- fail/fail_test.go --
+package fail
+
+import (
+       "os"
+       "testing"
+)
+
+func TestMain(m *testing.M) {
+       os.Stderr.WriteString("exitcode=1")
+       os.Exit(1)
+}
+-- skip/skip_test.go --
+package skip
+
+import (
+       "os"
+       "testing"
+)
+
+func TestMain(m *testing.M) {
+       os.Stderr.WriteString("skipping")
+       os.Exit(0)
+}