def test_onlySaveDot(self):
        """
        Passing an empty string for --image-directory/-i disables
        rendering images.
        """
        for arg in ('--image-directory', '-i'):
            self.digraphRecorder.reset()
            self.collectedOutput = []

            self.tool(argv=[self.fakeFQPN, arg, ''])
            self.assertFalse(any("image" in line
                                 for line in self.collectedOutput))

            self.assertEqual(len(self.digraphRecorder.saveCalls), 1)
            (call,) = self.digraphRecorder.saveCalls
            self.assertEqual("{}.dot".format(self.fakeFQPN),
                             call['filename'])

            self.assertFalse(self.digraphRecorder.renderCalls)

        Passing an empty string for --image-directory/-i disables
        rendering images.
        
stackoverflow/venv/lib/python3.6/site-packages/automat/_test/test_visualize.py