refactor: pull module cleaning into here

We don't need unittest_mixins' module cleaner anymore.

5 files changed, 86 insertions, 66 deletions

diff --git a/coverage/backward.py b/coverage/backward.py
index ac781ab9..779cd661 100644
--- a/coverage/backward.py
+++ b/coverage/backward.py
@@ -229,12 +229,6 @@ def format_local_datetime(dt):
         return dt.strftime('%Y-%m-%d %H:%M')
 
 
-def invalidate_import_caches():
-    """Invalidate any import caches that may or may not exist."""
-    if importlib and hasattr(importlib, "invalidate_caches"):
-        importlib.invalidate_caches()
-
-
 def import_local_file(modname, modfile=None):
     """Import a local file as a module.
 
diff --git a/tests/coveragetest.py b/tests/coveragetest.py
index f08de798..65678d52 100644
--- a/tests/coveragetest.py
+++ b/tests/coveragetest.py
@@ -22,8 +22,8 @@ from coverage.backward import StringIO, import_local_file, string_class, shlex_q
 from coverage.cmdline import CoverageScript
 
 from tests.helpers import arcs_to_arcz_repr, arcz_to_arcs, assert_count_equal
-from tests.helpers import run_command, SuperModuleCleaner
-from tests.mixins import StdStreamCapturingMixin, TempDirMixin, PytestBase
+from tests.helpers import run_command
+from tests.mixins import PytestBase, StdStreamCapturingMixin, SysPathModulesMixin, TempDirMixin
 
 
 # Status returns for the command line.
@@ -35,6 +35,7 @@ TESTS_DIR = os.path.dirname(__file__)
 
 class CoverageTest(
     StdStreamCapturingMixin,
+    SysPathModulesMixin,
     TempDirMixin,
     PytestBase,
 ):
@@ -61,22 +62,11 @@ class CoverageTest(
     def setup_test(self):
         super(CoverageTest, self).setup_test()
 
-        self.module_cleaner = SuperModuleCleaner()
-
         # Attributes for getting info about what happened.
         self.last_command_status = None
         self.last_command_output = None
         self.last_module_name = None
 
-    def clean_local_file_imports(self):
-        """Clean up the results of calls to `import_local_file`.
-
-        Use this if you need to `import_local_file` the same file twice in
-        one test.
-
-        """
-        self.module_cleaner.clean_local_file_imports()
-
     def start_import_stop(self, cov, modname, modfile=None):
         """Start coverage, import a file, then stop coverage.
 
diff --git a/tests/helpers.py b/tests/helpers.py
index 195fefde..d4dd33ea 100644
--- a/tests/helpers.py
+++ b/tests/helpers.py
@@ -8,15 +8,13 @@ import contextlib
 import glob
 import os
 import re
-import shutil
 import subprocess
 import sys
 
 import mock
-from unittest_mixins import ModuleCleaner
 
 from coverage import env
-from coverage.backward import invalidate_import_caches, unicode_class
+from coverage.backward import unicode_class
 from coverage.misc import output_encoding
 
 
@@ -115,29 +113,6 @@ def remove_files(*patterns):
             os.remove(fname)
 
 
-class SuperModuleCleaner(ModuleCleaner):
-    """Remember the state of sys.modules and restore it later."""
-
-    def clean_local_file_imports(self):
-        """Clean up the results of calls to `import_local_file`.
-
-        Use this if you need to `import_local_file` the same file twice in
-        one test.
-
-        """
-        # So that we can re-import files, clean them out first.
-        self.cleanup_modules()
-
-        # Also have to clean out the .pyc file, since the timestamp
-        # resolution is only one second, a changed file might not be
-        # picked up.
-        remove_files("*.pyc", "*$py.class")
-        if os.path.exists("__pycache__"):
-            shutil.rmtree("__pycache__")
-
-        invalidate_import_caches()
-
-
 # Map chars to numbers for arcz_to_arcs
 _arcz_map = {'.': -1}
 _arcz_map.update(dict((c, ord(c) - ord('0')) for c in '123456789'))
diff --git a/tests/mixins.py b/tests/mixins.py
index 7492e90c..ef9cdb6f 100644
--- a/tests/mixins.py
+++ b/tests/mixins.py
@@ -9,12 +9,16 @@ Some of these are transitional while working toward pure-pytest style.
 
 import os
 import os.path
+import shutil
 import sys
 import textwrap
 
 import pytest
 
 from coverage import env
+from coverage.backward import importlib
+
+from tests.helpers import remove_files
 
 
 class PytestBase(object):
@@ -78,26 +82,6 @@ class TempDirMixin(object):
             if old_dir is not None:
                 os.chdir(old_dir)
 
-    @pytest.fixture(autouse=True)
-    def _save_sys_path(self):
-        """Restore sys.path at the end of each test."""
-        old_syspath = sys.path[:]
-        try:
-            yield
-        finally:
-            sys.path = old_syspath
-
-    @pytest.fixture(autouse=True)
-    def _module_saving(self):
-        """Remove modules we imported during the test."""
-        old_modules = list(sys.modules)
-        try:
-            yield
-        finally:
-            added_modules = [m for m in sys.modules if m not in old_modules]
-            for m in added_modules:
-                del sys.modules[m]
-
     def make_file(self, filename, text="", bytes=b"", newline=None):
         """Create a file for testing.
 
@@ -138,6 +122,58 @@ class TempDirMixin(object):
         return filename
 
 
+class SysPathModulesMixin:
+    """Auto-restore sys.path and the imported modules at the end of each test."""
+
+    @pytest.fixture(autouse=True)
+    def _save_sys_path(self):
+        """Restore sys.path at the end of each test."""
+        old_syspath = sys.path[:]
+        try:
+            yield
+        finally:
+            sys.path = old_syspath
+
+    @pytest.fixture(autouse=True)
+    def _module_saving(self):
+        """Remove modules we imported during the test."""
+        self._old_modules = list(sys.modules)
+        try:
+            yield
+        finally:
+            self._cleanup_modules()
+
+    def _cleanup_modules(self):
+        """Remove any new modules imported since our construction.
+
+        This lets us import the same source files for more than one test, or
+        if called explicitly, within one test.
+
+        """
+        for m in [m for m in sys.modules if m not in self._old_modules]:
+            del sys.modules[m]
+
+    def clean_local_file_imports(self):
+        """Clean up the results of calls to `import_local_file`.
+
+        Use this if you need to `import_local_file` the same file twice in
+        one test.
+
+        """
+        # So that we can re-import files, clean them out first.
+        self._cleanup_modules()
+
+        # Also have to clean out the .pyc file, since the timestamp
+        # resolution is only one second, a changed file might not be
+        # picked up.
+        remove_files("*.pyc", "*$py.class")
+        if os.path.exists("__pycache__"):
+            shutil.rmtree("__pycache__")
+
+        if importlib and hasattr(importlib, "invalidate_caches"):
+            importlib.invalidate_caches()
+
+
 class StdStreamCapturingMixin:
     """
     Adapter from the pytest capsys fixture to more convenient methods.
diff --git a/tests/test_test_mixins.py b/tests/test_test_mixins.py
index b8a3ac67..028a19fd 100644
--- a/tests/test_test_mixins.py
+++ b/tests/test_test_mixins.py
@@ -4,7 +4,11 @@
 
 """Tests of code in tests/mixins.py"""
 
-from tests.mixins import TempDirMixin
+import pytest
+
+from coverage.backward import import_local_file
+
+from tests.mixins import TempDirMixin, SysPathModulesMixin
 
 
 class TempDirMixinTest(TempDirMixin):
@@ -54,3 +58,24 @@ class TempDirMixinTest(TempDirMixin):
         with open("binary.dat", "rb") as f:
             data = f.read()
         assert data == b"\x99\x33\x66hello\0"
+
+
+class SysPathModulessMixinTest(TempDirMixin, SysPathModulesMixin):
+    """Tests of SysPathModulesMixin."""
+
+    @pytest.mark.parametrize("val", [17, 42])
+    def test_module_independence(self, val):
+        self.make_file("xyzzy.py", "A = {}".format(val))
+        import xyzzy            # pylint: disable=import-error
+        assert xyzzy.A == val
+
+    def test_cleanup_and_reimport(self):
+        self.make_file("xyzzy.py", "A = 17")
+        xyzzy = import_local_file("xyzzy")
+        assert xyzzy.A == 17
+
+        self.clean_local_file_imports()
+
+        self.make_file("xyzzy.py", "A = 42")
+        xyzzy = import_local_file("xyzzy")
+        assert xyzzy.A == 42