refactor: replace unittest_mixins.EnvironmentAwareMixin with a pytest adapter

2 files changed, 20 insertions, 2 deletions

diff --git a/tests/coveragetest.py b/tests/coveragetest.py
index 3363fa89..906886f2 100644
--- a/tests/coveragetest.py
+++ b/tests/coveragetest.py
@@ -16,7 +16,7 @@ import sys
 import unittest
 
 import pytest
-from unittest_mixins import EnvironmentAwareMixin, TempDirMixin
+from unittest_mixins import TempDirMixin
 
 import coverage
 from coverage import env
@@ -25,7 +25,7 @@ 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, StopEverythingMixin
+from tests.mixins import EnvironmentAwareMixin, StdStreamCapturingMixin, StopEverythingMixin
 
 
 # Status returns for the command line.
diff --git a/tests/mixins.py b/tests/mixins.py
index 9d096d4d..5abaa759 100644
--- a/tests/mixins.py
+++ b/tests/mixins.py
@@ -16,6 +16,24 @@ import pytest
 from coverage.misc import StopEverything
 
 
+class EnvironmentAwareMixin:
+    """
+    Adapter from pytst monkeypatch fixture to our environment variable methods.
+    """
+    @pytest.fixture(autouse=True)
+    def _monkeypatch(self, monkeypatch):
+        """Get the monkeypatch fixture for our methods to use."""
+        self._envpatcher = monkeypatch
+
+    def set_environ(self, name, value):
+        """Set an environment variable `name` to be `value`."""
+        self._envpatcher.setenv(name, value)
+
+    def del_environ(self, name):
+        """Delete an environment variable, unless we set it."""
+        self._envpatcher.delenv(name)
+
+
 def convert_skip_exceptions(method):
     """A decorator for test methods to convert StopEverything to SkipTest."""
     @functools.wraps(method)