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0b990a82a5
Moving the `captured_output` function to own file. Adding homegrown unit testing helper classes `Stub` and `Mock`. The issue is that the unittest.mock was added in Python 3.3 and we need to run on Python 2.7. `Stub` and `Mock` were organically developed as minimal implementations to support the common testing patterns used on the original branch, but since I’m rewriting the commit history to provide an easily digestible narrative, it makes sense to introduce them here in one step as a custom unit testing library.
89 lines
3.0 KiB
Python
89 lines
3.0 KiB
Python
#!/usr/bin/python
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# -*- coding: utf-8 -*-
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# ===--- test_utils.py ---------------------------------------------------===//
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#
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# This source file is part of the Swift.org open source project
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#
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# Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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# Licensed under Apache License v2.0 with Runtime Library Exception
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#
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# See https://swift.org/LICENSE.txt for license information
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# See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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#
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# ===---------------------------------------------------------------------===//
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"""
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Homegrown unit testing helpers.
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The issue is that the unittest.mock was added in Python 3.3 and we need to run
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on Python 2.7.
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`Stub` and `Mock` are very rudimentary and support only the limited subset of
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common unit testing patterns that is used in this project.
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"""
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import sys
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from StringIO import StringIO
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from contextlib import contextmanager
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@contextmanager
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def captured_output():
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"""Capture stdout and stderr and return their output as string buffers."""
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new_out, new_err = StringIO(), StringIO()
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old_out, old_err = sys.stdout, sys.stderr
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try:
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sys.stdout, sys.stderr = new_out, new_err
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yield sys.stdout, sys.stderr
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finally:
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sys.stdout, sys.stderr = old_out, old_err
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class Stub:
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"""Object literal stub for value objects."""
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def __init__(self, **attributes):
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"""All named parameters will create properties on this object."""
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self.__dict__.update(attributes)
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class Mock(object):
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"""Minimal infrastructure for manually mocking calls to single method.
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Classes inheriting from Mock are expected to create their own mock of the
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tested method with appropriate signature, which appends the call arguments
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as tuple to the `calls` list and returns the canned response retrieved from
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the `respond` dictionary.
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"""
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def __init__(self, responses=None):
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"""Optionaly initialized with a list of expected calls. See expect."""
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self.calls = []
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self.expected = []
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self.respond = dict()
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responses = responses or []
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for call_args, response in responses:
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self.expect(call_args, response)
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def expect(self, call_args, response):
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"""Expect invocation of tested method with given arguments.
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Stores the canned reponse in the `respond` dictionary.
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"""
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call_args = tuple(call_args)
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self.expected.append(call_args)
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self.respond[call_args] = response
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def assert_called_with(self, expected_args):
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"""Verify that the tested method was called with provided arguments."""
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expected_args = tuple(expected_args)
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assert expected_args in self.calls, (
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'Expected: {0} in Called: {1}'.format(expected_args, self.calls))
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def assert_called_all_expected(self):
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"""Verify that all expeced invocations of tested method were called."""
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assert self.calls == self.expected, (
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'\nExpected: {0}, \n Called: {1}'.format(
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self.expected, self.calls))
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