Fixed assertion rewriting for plugins in development mode

CHANGELOG.rst

@@ -7,7 +7,9 @@
 
 *
 
-*
+* Assertions are now being rewritten for plugins in development mode
+  (``pip install -e``) (`#1934`_).
+  Thanks `@nicoddemus`_ for the PR.
 
 *
 
@@ -17,6 +19,7 @@
 .. _@philpep: https://github.com/philpep
 
 .. _#1905: https://github.com/pytest-dev/pytest/issues/1905
+.. _#1934: https://github.com/pytest-dev/pytest/issues/1934
 
 
 3.0.2

_pytest/config.py

@@ -954,16 +954,21 @@ def _consider_importhook(self, args, entrypoint_name):
             else:
                 self.pluginmanager.rewrite_hook = hook
                 for entrypoint in pkg_resources.iter_entry_points('pytest11'):
-                    for entry in entrypoint.dist._get_metadata('RECORD'):
-                        fn = entry.split(',')[0]
-                        is_simple_module = os.sep not in fn and fn.endswith('.py')
-                        is_package = fn.count(os.sep) == 1 and fn.endswith('__init__.py')
-                        if is_simple_module:
-                            module_name, ext = os.path.splitext(fn)
-                            hook.mark_rewrite(module_name)
-                        elif is_package:
-                            package_name = os.path.dirname(fn)
-                            hook.mark_rewrite(package_name)
+                    # 'RECORD' available for plugins installed normally (pip install)
+                    # 'SOURCES.txt' available for plugins installed in dev mode (pip install -e)
+                    # for installed plugins 'SOURCES.txt' returns an empty list, and vice-versa
+                    # so it shouldn't be an issue
+                    for metadata in ('RECORD', 'SOURCES.txt'):
+                        for entry in entrypoint.dist._get_metadata(metadata):
+                            fn = entry.split(',')[0]
+                            is_simple_module = os.sep not in fn and fn.endswith('.py')
+                            is_package = fn.count(os.sep) == 1 and fn.endswith('__init__.py')
+                            if is_simple_module:
+                                module_name, ext = os.path.splitext(fn)
+                                hook.mark_rewrite(module_name)
+                            elif is_package:
+                                package_name = os.path.dirname(fn)
+                                hook.mark_rewrite(package_name)
         self._warn_about_missing_assertion(mode)
 
     def _warn_about_missing_assertion(self, mode):

testing/test_assertion.py

@@ -108,7 +108,8 @@ def test_foo(pytestconfig):
         assert result.ret == 0
 
     @pytest.mark.parametrize('mode', ['plain', 'rewrite'])
-    def test_installed_plugin_rewrite(self, testdir, mode):
+    @pytest.mark.parametrize('plugin_state', ['development', 'installed'])
+    def test_installed_plugin_rewrite(self, testdir, mode, plugin_state):
         # Make sure the hook is installed early enough so that plugins
         # installed via setuptools are re-written.
         testdir.tmpdir.join('hampkg').ensure(dir=1)
@@ -135,13 +136,22 @@ def check(values, value):
             'mainwrapper.py': """
             import pytest, pkg_resources
 
+            plugin_state = "{plugin_state}"
+
             class DummyDistInfo:
                 project_name = 'spam'
                 version = '1.0'
 
                 def _get_metadata(self, name):
-                    return ['spamplugin.py,sha256=abc,123',
-                            'hampkg/__init__.py,sha256=abc,123']
+                    # 'RECORD' meta-data only available in installed plugins
+                    if name == 'RECORD' and plugin_state == "installed":
+                        return ['spamplugin.py,sha256=abc,123',
+                                'hampkg/__init__.py,sha256=abc,123']
+                    # 'SOURCES.txt' meta-data only available for plugins in development mode
+                    elif name == 'SOURCES.txt' and plugin_state == "development":
+                        return ['spamplugin.py',
+                                'hampkg/__init__.py']
+                    return []
 
             class DummyEntryPoint:
                 name = 'spam'
@@ -159,7 +169,7 @@ def iter_entry_points(name):
 
             pkg_resources.iter_entry_points = iter_entry_points
             pytest.main()
-            """,
+            """.format(plugin_state=plugin_state),
             'test_foo.py': """
             def test(check_first):
                 check_first([10, 30], 30)