Given this Python code:
elif request.method == 'DELETE':
try:
os.remove(full_file)
return jsonify({'results':'purged %s' % full_file})
except OSError as e:
if e.errno != errno.ENOENT:
raise
return jsonify({'results':'file not present: %s' % full_file})
I want to test all possible paths, including the exception handling. Using Mock, it's easy enough to raise an exception, which I do with this code:
with patch('os.remove', new=Mock(side_effect=OSError(errno.ENOENT))):
self.assertRaises(OSError, self.app.delete, file_URL) # broken
Mock raises an exception, which has a printed value of 2 (ENOENT) – but e.errno is set to NONE. And so far, I have not found a way to set it. The result is, the exception always gets re-raised, and I never reach the last line of code, in my unit test.
I've also tried creating a dummy class with errno set, and returning that. But unless it has *side_effect* set to be called, it doesn't raise an exception, and when I set side_effect, I don't get the object.errno as a return value.
Is there a way to have Mock raise an Exception, where that Exception object has the errno attribute set?
Best Answer
Pass two arguments to OSError constructor. (First one should be
errno
).For example: