Make monkeypatch invocation-scoped

Author: nicoddemus

_pytest/monkeypatch.py

@@ -10,7 +10,7 @@
 RE_IMPORT_ERROR_NAME = re.compile("^No module named (.*)$")
 
 
-@pytest.fixture
+@pytest.fixture(scope='invocation')
 def monkeypatch(request):
     """The returned ``monkeypatch`` fixture provides these
     helper methods to modify objects, dictionaries or os.environ::
@@ -25,9 +25,11 @@ def monkeypatch(request):
         monkeypatch.chdir(path)
 
     All modifications will be undone after the requesting
-    test function has finished. The ``raising``
+    test function or fixture has finished. The ``raising``
     parameter determines if a KeyError or AttributeError
     will be raised if the set/deletion operation has no target.
+
+    This fixture is ``invocation``-scoped.
     """
     mpatch = MonkeyPatch()
     request.addfinalizer(mpatch.undo)
@@ -97,7 +99,8 @@ def __repr__(self):
 
 
 class MonkeyPatch:
-    """ Object keeping a record of setattr/item/env/syspath changes. """
+    """ Object returned by the ``monkeypatch`` fixture keeping a record of setattr/item/env/syspath changes.
+    """
 
     def __init__(self):
         self._setattr = []

doc/en/invocation-fixture.rst

@@ -9,9 +9,6 @@ Invocation-scoped fixtures
     This feature is experimental, so if decided that it brings too much problems
     or considered too complicated it might be removed in pytest ``3.1``.
 
-    ``tmpdir`` and ``monkeypatch`` might become ``invocation`` scoped
-    fixtures in the future if decided to keep invocation-scoped fixtures.
-
 Fixtures can be defined with ``invocation`` scope, meaning that the fixture
 can be requested by fixtures from any scope, but when they do they assume
 the same scope as the fixture requesting it.

doc/en/monkeypatch.rst

@@ -6,14 +6,17 @@ Monkeypatching/mocking modules and environments
 
 Sometimes tests need to invoke functionality which depends
 on global settings or which invokes code which cannot be easily
-tested such as network access.  The ``monkeypatch`` function argument
+tested such as network access.  The ``monkeypatch`` fixture
 helps you to safely set/delete an attribute, dictionary item or
 environment variable or to modify ``sys.path`` for importing.
 See the `monkeypatch blog post`_ for some introduction material
 and a discussion of its motivation.
 
 .. _`monkeypatch blog post`: http://tetamap.wordpress.com/2009/03/03/monkeypatching-in-unit-tests-done-right/
 
+As of pytest-3.0, the ``monkeypatch`` fixture is :ref:`invocation-scoped <invocation_scoped_fixture>`
+meaning it can be requested from fixtures of any scope.
+
 Simple example: monkeypatching functions
 ---------------------------------------------------
 
@@ -53,27 +56,31 @@ This autouse fixture will be executed for each test function and it
 will delete the method ``request.session.Session.request`` 
 so that any attempts within tests to create http requests will fail.
 
-example: setting an attribute on some class
-------------------------------------------------------
+example: setting an environment variable for the test session
+-------------------------------------------------------------
 
-If you need to patch out ``os.getcwd()`` to return an artificial
-value::
+If you would like for an environment variable to be
+configured for the entire test session, you can add this to your
+top-level ``conftest.py`` file:
 
-    def test_some_interaction(monkeypatch):
-        monkeypatch.setattr("os.getcwd", lambda: "/")
+.. code-block:: python
+
+    # content of conftest.py
+    @pytest.fixture(scope='session', autouse=True)
+    def enable_debugging(monkeypatch):
+        monkeypatch.setenv("DEBUGGING_VERBOSITY", "4")
 
-which is equivalent to the long form::
+This auto-use fixture will set the ``DEBUGGING_VERBOSITY`` environment variable for
+the entire test session.
 
-    def test_some_interaction(monkeypatch):
-        import os
-        monkeypatch.setattr(os, "getcwd", lambda: "/")
-    
+Note that the ability to use a ``monkeypatch`` fixture from a ``session``-scoped
+fixture was added in pytest-3.0.
 
 
-Method reference of the monkeypatch function argument
------------------------------------------------------
+Method reference of the monkeypatch fixture
+-------------------------------------------
 
-.. autoclass:: monkeypatch
+.. autoclass:: MonkeyPatch
     :members: setattr, replace, delattr, setitem, delitem, setenv, delenv, syspath_prepend, chdir, undo
 
 ``monkeypatch.setattr/delattr/delitem/delenv()`` all

testing/test_monkeypatch.py

@@ -328,4 +328,36 @@ def test_issue1338_name_resolving():
     try:
          monkeypatch.delattr('requests.sessions.Session.request')
     finally:
-        monkeypatch.undo()
+        monkeypatch.undo()
+
+
+def test_invocation_scoped_monkeypatch(testdir):
+    testdir.makeconftest("""
+        import pytest
+        import sys
+
+        @pytest.fixture(scope='module')
+        def stamp_sys(monkeypatch):
+            monkeypatch.setattr(sys, 'module_stamped', True, raising=False)
+    """)
+    testdir.makepyfile(test_inv_mokeypatch_1="""
+        import sys
+
+        def test_stamp_1(monkeypatch, stamp_sys):
+            assert sys.module_stamped
+            monkeypatch.setattr(sys, 'function_stamped', True, raising=False)
+            assert sys.function_stamped
+
+        def test_stamp_2(monkeypatch):
+            assert sys.module_stamped
+            assert not hasattr(sys, 'function_stamped')
+    """)
+    testdir.makepyfile(test_inv_mokeypatch_2="""
+        import sys
+
+        def test_no_stamps():
+            assert not hasattr(sys, 'module_stamped')
+            assert not hasattr(sys, 'function_stamped')
+    """)
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines(['*3 passed*'])