How to test for exit codes in go without exiting the testcase when the exit code is != 0

I'm trying to write a unit test in go for a function that returns non-zero exit codes. I'm developing a CLI app with cobra to validate semantic versions. In case a validation fails, I return some information in JSON and exit with os.Exit(1).

Now I want to test if this really works as intended. In my test I pass with one data set that should success and return 0 and one that should fail and return 1. But the test that should return 1 always cancels the test and hence cancels all following iterations. This is my code:

func Test_ShouldGetCorrectExitCode(t *testing.T) {
	testCases := []struct {
		args          []string
		shouldBeValid bool
	}{
		{[]string{"0.1.0"}, false},
		{[]string{"v0.1.0"}, true},
	}
	for _, tc := range testCases {
		assert := assert.New(t)
		cmd := NewCmdValidate()
		cmd.SetArgs(tc.args)
		err := cmd.Execute()
		assert.Nil(err)
	}
}

So far the assertions are not really sophisticated because I don't get the test to run the way I expect. Anyone got an idea how I can test for exit codes in go?

The best solution is to not call os.Exit from your function under test. A good practice can be to only call os.Exit from main(), and instead have your function return an exit status, which you can easily test for. Example:

func main() {
    os.Exit(run())
}
func run() int {
  /* Things to test here */
}

Then in your test:

func TestRun(t *testing.T) {
    t.Run("should succeed", func(t *testing.T) {
        status := run()
        if status != 0 {
            t.Errorf("Unexpected exit status: %d", status)
    })
    t.Run("should fail", func(t *testing.T) {
        status := run()
        if status != 1 {
            t.Errorf("Unexpected status code: %d", status)
        }
    })
}