From 3574eaa0c903cd8ed862b8bff896ce0a73412321 Mon Sep 17 00:00:00 2001 From: Sebastiaan Zeeff <33516116+SebastiaanZ@users.noreply.github.com> Date: Mon, 24 Feb 2020 10:06:09 +0100 Subject: Use MagicMock as return value for _get_diff mock The `_get_diff` method of TestSyncer class is mocked using an AsyncMock object. By default, when an AsyncMock object is called **and awaited**, it returns a child mock of the same time (another AsyncMock) according to the "the child is a like the parent" principle. This means that the _get_diff method will return an AsyncMock unless a different return_value is explicitly provided. Because of that "child is like parent" behavior, this will happen in lines 194-196 of bot.cogs.sync.syncers (annotations added by me): ``` // `diff` will be a child AsyncMock as "child is like parent" diff = await self._get_diff(guild) // `diff._asdict` will be an AsyncMock as "child is like parent" and, // after being called, it will return an unawaited coroutine object // we assign the name `diff_dict`: diff_dict = diff._asdict() // `diff_dict` is still an unawaited coroutine object meaning that it // doesn't have an `items()` method: totals = {k: len(v) for k, v in diff_dict.items() if v is not None} ``` Original, unannotated: https://github.com/python-discord/bot/blob/c81a4d401ea434e98b0a1ece51d3d10f1a3ad226/bot/cogs/sync/syncers.py#L194-L196 This will lead to the following exception when running the tests: ```py ====================================================================== ERROR: test_sync_confirmation_context_redirect (tests.bot.cogs.sync.test_base.SyncerSyncTests) (ctx=None, author=, message=None) If ctx is given, a new message should be sent and author should be ctx's author. ---------------------------------------------------------------------- Traceback (most recent call last): File "/home/sebastiaan/pydis/repositories/bot/tests/bot/cogs/sync/test_base.py", line 348, in test_sync_confirmation_context_redirect await self.syncer.sync(guild, ctx) File "/home/sebastiaan/pydis/repositories/bot/bot/cogs/sync/syncers.py", line 196, in sync totals = {k: len(v) for k, v in diff_dict.items() if v is not None} AttributeError: 'coroutine' object has no attribute 'items' ``` The solution is to assign an explicit return value so the parent mock doesn't "guess" and return an object of its own type. I previously did that by providing a specific `_Diff` object as the return value, but I should have gone with a `MagicMock` to signify that it's not an important return value; it's just something that needs to support/mimic the API we use on it. So that's what this commit adds. --- tests/bot/cogs/sync/test_base.py | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tests') diff --git a/tests/bot/cogs/sync/test_base.py b/tests/bot/cogs/sync/test_base.py index 17aa4198b..d17a27409 100644 --- a/tests/bot/cogs/sync/test_base.py +++ b/tests/bot/cogs/sync/test_base.py @@ -339,8 +339,8 @@ class SyncerSyncTests(unittest.IsolatedAsyncioTestCase): if ctx is not None: ctx.send.return_value = message - diff = _Diff({1, 2, 3}, {4, 5}, None) - self.syncer._get_diff.return_value = diff + # Make sure `_get_diff` returns a MagicMock, not an AsyncMock + self.syncer._get_diff.return_value = mock.MagicMock() self.syncer._get_confirmation_result = mock.AsyncMock(return_value=(False, None)) -- cgit v1.2.3