os/signal: TestTerminalSignal failures on Darwin builders

[bcmills]

2020-02-19T20:37:54-b15fd6b/darwin-amd64-10_11
2019-10-31T21:47:08-ef03c44/darwin-amd64-race

--- FAIL: TestTerminalSignal (10.01s)
    signal_cgo_test.go:145: "PS1='prompt> '\r\n"
    signal_cgo_test.go:145: "bash-3.2$ PS1='prompt> '\r\n"
    signal_cgo_test.go:145: "prompt> GO_TEST_TERMINAL_SIGNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w00\r<GNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w000                         \b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b0gn/T/workdir-host-darwin\r<3rs1s93538b4x20g46cj_w0000gn/T/workdir-host-darwin-                         \b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b10_11/tmp/go-build2962210\r<gn/T/workdir-host-darwin-10_11/tmp/go-build29622109                         \b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b3/b143/signal.test -test.\r<0_11/tmp/go-build296221093/b143/signal.test -test.r                         \b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\bun=TestTerminalSignal\r\n"
    signal_cgo_test.go:145: "test program entering read\r\n"
    signal_cgo_test.go:145: "^Z\r\n"
    signal_cgo_test.go:145: "[1]+  Stopped                 GO_TEST_TERMINAL_SIGNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w0000gn/T/workdir-host-darwin-10_11/tmp/go-build296221093/b143/signal.test -test.run=TestTerminalSignal\r\n"
    signal_cgo_test.go:145: "prompt> fg\r\n"
    signal_cgo_test.go:145: "GO_TEST_TERMINAL_SIGNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w0000gn/T/workdir-host-darwin-10_11/tmp/go-build296221093/b143/signal.test -test.run=TestTerminalSignal\r\n"
    signal_cgo_test.go:145: "\r\n"
    signal_cgo_test.go:145: "[1]+  Stopped                 GO_TEST_TERMINAL_SIGNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w0000gn/T/workdir-host-darwin-10_11/tmp/go-build296221093/b143/signal.test -test.run=TestTerminalSignal\r\n"
    signal_cgo_test.go:145: "prompt> \r\n"
    signal_cgo_test.go:145: "prompt> exit $?\r\n"
    signal_cgo_test.go:145: "exit\r\n"
    signal_cgo_test.go:145: "There are stopped jobs.\r\n"
    signal_cgo_test.go:128: "prompt> "
    signal_cgo_test.go:237: subprogram failed: signal: killed
FAIL
FAIL	os/signal	15.203s

CC @ianlancetaylor @cherrymui @bradfitz

[bcmills]

2020-02-22T17:58:24-dad553d/darwin-amd64-10_11

[bcmills]

The test is also flaky on darwin-amd64-10_12, but with a different failure mode (a test timeout rather than signal: killed):

2020-03-13T00:19:08-85e87f9/darwin-amd64-10_12
2019-10-25T23:25:32-8c58615/darwin-amd64-10_12

[bcmills]

2020-04-20T19:36:50-0239a5c/darwin-amd64-10_15
2020-02-22T17:58:24-dad553d/darwin-amd64-10_11
2020-02-19T20:37:54-b15fd6b/darwin-amd64-10_11
2019-10-31T21:47:08-ef03c44/darwin-amd64-race

[prattmic]

This flake has been occurring again on the new darwin-amd64-*-aws builders. We will see if https://go.dev/cl/435735 stops the failures.

[ZekeLu]

I'm afraid that CL 435735 does not help.

I have confirmed that, on my local MacOS, when the test is run with go tool dist test go_test:os/signal, the same pattern of the \b characters are added. But the test did not fail. Then I think maybe the full path of the signal.test file matters. So I created the same path, copied the signal.test file into it, and then changed the test to send this path to bash, the test still did not fail. The output is attached to the end of this comment. The highlighted lines are totally the same as that in the first comment of this issue. And I have tried to run go tool dist test go_test:os/signal in a loop on the code without CL 43735 (with some modifications to run TestTerminalSignal only). I can not reproduce the issue in 5000+ runs.

 ##### Test execution environment.
 # GOARCH: amd64
 # CPU: Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz
 # GOOS: darwin
 # OS Version: Darwin 21.6.0 Darwin Kernel Version 21.6.0: Mon Aug 22 20:17:10 PDT 2022; root:xnu-8020.140.49~2/RELEASE_X86_64 x86_64
 
 ##### Testing packages.
 === RUN   TestTerminalSignal
 === PAUSE TestTerminalSignal
 === CONT  TestTerminalSignal
     signal_cgo_test.go:145: "PS1='prompt> '\r\n"
     signal_cgo_test.go:145: "\r\n"
     signal_cgo_test.go:145: "The default interactive shell is now zsh.\r\n"
     signal_cgo_test.go:145: "To update your account to use zsh, please run `chsh -s /bin/zsh`.\r\n"
     signal_cgo_test.go:145: "For more details, please visit https://support.apple.com/kb/HT208050.\r\n"
+    signal_cgo_test.go:145: "bash-3.2$ PS1='prompt> '\r\n"
+    signal_cgo_test.go:145: "prompt> GO_TEST_TERMINAL_SIGNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w00\r<GNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w000                         \b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b0gn/T/workdir-host-darwin\r<3rs1s93538b4x20g46cj_w0000gn/T/workdir-host-darwin-                         \b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b10_11/tmp/go-build2962210\r<gn/T/workdir-host-darwin-10_11/tmp/go-build29622109                         \b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b3/b143/signal.test -test.\r<0_11/tmp/go-build296221093/b143/signal.test -test.r                         \b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\bun=TestTerminalSignal\r\n"
+    signal_cgo_test.go:145: "test program entering read\r\n"
+    signal_cgo_test.go:145: "^Z\r\n"
+    signal_cgo_test.go:145: "[1]+  Stopped                 GO_TEST_TERMINAL_SIGNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w0000gn/T/workdir-host-darwin-10_11/tmp/go-build296221093/b143/signal.test -test.run=TestTerminalSignal\r\n"
+    signal_cgo_test.go:145: "prompt> fg\r\n"
+    signal_cgo_test.go:145: "GO_TEST_TERMINAL_SIGNALS=1 /var/folders/dx/k53rs1s93538b4x20g46cj_w0000gn/T/workdir-host-darwin-10_11/tmp/go-build296221093/b143/signal.test -test.run=TestTerminalSignal\r\n"
+    signal_cgo_test.go:145: "\r\n"
     signal_cgo_test.go:145: "read newline\r\n"
     signal_cgo_test.go:145: "prompt> exit $?\r\n"
     signal_cgo_test.go:145: "exit\r\n"
 --- PASS: TestTerminalSignal (0.13s)
 PASS
 ok      os/signal       0.499s

[prattmic]

That's too bad, but thanks for taking a look.