Tests: optionally prevent autospec helper from passing mocks

Not everything that's decorated needs the mocks that are patched. Being
required to add the args to the test function anyway is annoying. It's
especially bad if trying to decorate an entire test suite, as every
test would need the args.

Move the definition to a separate module to keep things cleaner.

2 files changed, 66 insertions, 19 deletions

diff --git a/tests/_autospec.py b/tests/_autospec.py
new file mode 100644
index 000000000..ee2fc1973
--- /dev/null
+++ b/tests/_autospec.py
@@ -0,0 +1,64 @@
+import contextlib
+import functools
+import unittest.mock
+from typing import Callable
+
+
[email protected](unittest.mock._patch.decoration_helper)
[email protected]
+def _decoration_helper(self, patched, args, keywargs):
+    """Skips adding patchings as args if their `dont_pass` attribute is True."""
+    # Don't ask what this does. It's just a copy from stdlib, but with the dont_pass check added.
+    extra_args = []
+    with contextlib.ExitStack() as exit_stack:
+        for patching in patched.patchings:
+            arg = exit_stack.enter_context(patching)
+            if not getattr(patching, "dont_pass", False):
+                # Only add the patching as an arg if dont_pass is False.
+                if patching.attribute_name is not None:
+                    keywargs.update(arg)
+                elif patching.new is unittest.mock.DEFAULT:
+                    extra_args.append(arg)
+
+        args += tuple(extra_args)
+        yield args, keywargs
+
+
[email protected](unittest.mock._patch.copy)
+def _copy(self):
+    """Copy the `dont_pass` attribute along with the standard copy operation."""
+    patcher_copy = _copy.original(self)
+    patcher_copy.dont_pass = getattr(self, "dont_pass", False)
+    return patcher_copy
+
+
+# Monkey-patch the patcher class :)
+_copy.original = unittest.mock._patch.copy
+unittest.mock._patch.copy = _copy
+unittest.mock._patch.decoration_helper = _decoration_helper
+
+
+def autospec(target, *attributes: str, pass_mocks: bool = True, **patch_kwargs) -> Callable:
+    """
+    Patch multiple `attributes` of a `target` with autospecced mocks and `spec_set` as True.
+
+    If `pass_mocks` is True, pass the autospecced mocks as arguments to the decorated object.
+    """
+    # Caller's kwargs should take priority and overwrite the defaults.
+    kwargs = dict(spec_set=True, autospec=True)
+    kwargs.update(patch_kwargs)
+
+    # Import the target if it's a string.
+    # This is to support both object and string targets like patch.multiple.
+    if type(target) is str:
+        target = unittest.mock._importer(target)
+
+    def decorator(func):
+        for attribute in attributes:
+            patcher = unittest.mock.patch.object(target, attribute, **kwargs)
+            if not pass_mocks:
+                # A custom attribute to keep track of which patchings should be skipped.
+                patcher.dont_pass = True
+            func = patcher(func)
+        return func
+    return decorator
diff --git a/tests/helpers.py b/tests/helpers.py
index facc4e1af..6cf5d12bd 100644
--- a/tests/helpers.py
+++ b/tests/helpers.py
@@ -5,7 +5,7 @@ import itertools
 import logging
 import unittest.mock
 from asyncio import AbstractEventLoop
-from typing import Callable, Iterable, Optional
+from typing import Iterable, Optional
 
 import discord
 from aiohttp import ClientSession
@@ -14,6 +14,7 @@ from discord.ext.commands import Context
 from bot.api import APIClient
 from bot.async_stats import AsyncStatsClient
 from bot.bot import Bot
+from tests._autospec import autospec  # noqa: F401 other modules import it via this module
 
 
 for logger in logging.Logger.manager.loggerDict.values():
@@ -26,24 +27,6 @@ for logger in logging.Logger.manager.loggerDict.values():
     logger.setLevel(logging.CRITICAL)
 
 
-def autospec(target, *attributes: str, **kwargs) -> Callable:
-    """Patch multiple `attributes` of a `target` with autospecced mocks and `spec_set` as True."""
-    # Caller's kwargs should take priority and overwrite the defaults.
-    kwargs = {'spec_set': True, 'autospec': True, **kwargs}
-
-    # Import the target if it's a string.
-    # This is to support both object and string targets like patch.multiple.
-    if type(target) is str:
-        target = unittest.mock._importer(target)
-
-    def decorator(func):
-        for attribute in attributes:
-            patcher = unittest.mock.patch.object(target, attribute, **kwargs)
-            func = patcher(func)
-        return func
-    return decorator
-
-
 class HashableMixin(discord.mixins.EqualityComparable):
     """
     Mixin that provides similar hashing and equality functionality as discord.py's `Hashable` mixin.