iotest_test.go unit test failture

[gtchaos]

func TestTempFile(t *testing.T) {
f, cleanup := TempFile(t)
if _, err := f.Write([]byte("test")); err != nil {
t.Fatalf("temp file not writable: %v", err)
}
cleanup()
// Confirm closed
if err := f.Close(); err != syscall.EINVAL {
t.Errorf("temp file was not closed by cleanup func")
}

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if call file.Close() again, it probably return error "file already closed" rather than "syscall.EINVAL"