From: =?utf-8?b?T3R0byBLZWvDpGzDpGluZW4=?= Date: Sat, 23 Aug 2025 22:35:05 +0000 Subject: Fix TestTee panic on Spawn error seen on ppc64el The `TestTee` function was susceptible to a panic due to a nil pointer dereference if the `Spawn` function failed as observed on the `ppc64el` architecture during autopkgtests: github.com/google/goexpect dh_auto_test -O--builddirectory=debian/.build/upstream -O--buildsystem=golang ^Icd debian/.build/upstream && go test -vet=off -v -p 16 github.com/google/goexpect === RUN TestBatcher 2025/08/22 06:57:28 at login prompt 2025/08/22 06:57:28 at password prompt 2025/08/22 06:57:28 Done sent E0822 06:57:28.425817 7480 expect_test.go:138] Accept failed: accept tcp [::]:42685: use of closed network connection --- PASS: TestBatcher (0.08s) === RUN TestTee --- FAIL: TestTee (0.00s) panic: runtime error: invalid memory address or nil pointer dereference [recovered] ^Ipanic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x2e6c64] goroutine 60 [running]: testing.tRunner.func1.2({0x392ec0, 0x6cd9e0}) ^I/usr/lib/go-1.24/src/testing/testing.go:1734 +0x1d8 testing.tRunner.func1() ^I/usr/lib/go-1.24/src/testing/testing.go:1737 +0x33c panic({0x392ec0?, 0x6cd9e0?}) ^I/usr/lib/go-1.24/src/runtime/panic.go:792 +0x154 github.com/google/goexpect.(*GExpect).check(0x37aa40?) ^I/tmp/autopkgtest-lxc.onolzjvd/downtmp/autopkgtest_tmp/debian/.build/upstream/src/github.com/google/goexpect/expect.go:690 +0x34 github.com/google/goexpect.(*GExpect).Send(0x0, {0x4004e6, 0x7}) ^I/tmp/autopkgtest-lxc.onolzjvd/downtmp/autopkgtest_tmp/debian/.build/upstream/src/github.com/google/goexpect/expect.go:1223 +0x4c github.com/google/goexpect.TestTee(0xc00034ac40) ^I/tmp/autopkgtest-lxc.onolzjvd/downtmp/autopkgtest_tmp/debian/.build/upstream/src/github.com/google/goexpect/expect_test.go:710 +0x178 testing.tRunner(0xc00034ac40, 0x41a0e0) ^I/usr/lib/go-1.24/src/testing/testing.go:1792 +0x110 created by testing.(*T).Run in goroutine 1 ^I/usr/lib/go-1.24/src/testing/testing.go:1851 +0x3ec FAIL^Igithub.com/google/goexpect^I0.093s FAIL dh_auto_test: error: cd debian/.build/upstream && go test -vet=off -v -p 16 github.com/google/goexpect returned exit code 1 make: *** [debian/rules:9: build] Error 25 The `Spawn` function can return an error and a nil `GExpect` object if it fails to initialize the process. The test, however, did not check for this error and proceeded to call methods on the potentially nil `GExpect` object, leading to a panic. If `Spawn` returns an error, the test will now fail gracefully with a `t.Fatalf` message, preventing the nil pointer dereference and subsequent panic. This makes the test more robust against transient failures or environment-specific issues during process spawning. --- expect_test.go | 3 +++ 1 file changed, 3 insertions(+) diff --git a/expect_test.go b/expect_test.go index 31c1d76..ede0ee7 100644 --- a/expect_test.go +++ b/expect_test.go @@ -706,6 +706,9 @@ func TestTee(t *testing.T) { // Send abcdef to cat 4096 times. input := "abcdef\n" e, _, err := Spawn("cat", 400*time.Millisecond, Tee(f), CheckDuration(1*time.Millisecond)) + if err != nil { + t.Fatalf("Spawn failed: %v", err) + } for i := 0; i < 4096; i++ { e.Send(input) re := regexp.MustCompile(input)