Go Test delete logger.SetLogging log file

Question

I have a TestCase for a function that defines a log file path, then sets logger, so that log.* statements are written to standard out and the log file:

lf, err := os.Create(logFile)
mw := io.MultiWriter(os.Stdout, lf)
log.SetOutput(mw)

In my Test case I'm attempting to cleanup at the end, but it appears there is a lock on the file still, which means the Os.Remove() call is not working (or even returning an error)

I've tried to SetOutput to nil as well as using a defer statement.

func TestSetLogging(t *testing.T) {
// do stuff
...
log.Println("this should be in logger file")

// cleanup
log.SetOutput(nil)
defer os.Remove(logFile)
}

Yet, the logFile still appears on disk. How can I delete this file?

You shouldn't have a defer call at the end of the function. Are you exiting the test early in the // do stuff? Maybe post all your code to make things easier. — chris
– chris, Commented Jun 27, 2018 at 4:43

Maxim · Accepted Answer · 2018-06-27 17:10:24Z

1

Try calling:

lf.Close()

before

os.Remove(logFile)

or you can replace

defer os.Remove(logFile)

with:

defer func() {
  lf.Close()
  os.Remove(logFile)
}()

answered Jun 27, 2018 at 17:10

Maxim

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3 Comments

buildmaestro Over a year ago

I see. hmm unfortunately the file was created in a function and lf is out of scope. It does explain why it's happening though.

buildmaestro Over a year ago

I modified the function that sets logging to also return the *os.File handle. Then used your suggestion, but I had to reverse the order for the defer statements: defer os.Remove(logFile); defer lf.Close()

Maxim Over a year ago

You have to close file handle before removing the file. The file will not really be deleted until the last handle is closed.

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