refactor: remove reliance on unittest_mixins.StdStreamCapturingMixin

This is another step toward removing unittest.TestCase as a base class.

1 files changed, 31 insertions, 0 deletions

diff --git a/tests/mixins.py b/tests/mixins.py
index 97ca093c..ab0623c0 100644
--- a/tests/mixins.py
+++ b/tests/mixins.py
@@ -10,6 +10,8 @@ Some of these are transitional while working toward pure-pytest style.
 import functools
 import types
 
+import pytest
+
 from coverage.backunittest import unittest
 from coverage.misc import StopEverything
 
@@ -37,3 +39,32 @@ class SkipConvertingMetaclass(type):
 
 
 StopEverythingMixin = SkipConvertingMetaclass('StopEverythingMixin', (), {})
+
+
+class StdStreamCapturingMixin:
+    """
+    Adapter from the pytest capsys fixture to more convenient methods.
+
+    This doesn't also output to the real stdout, so we probably want to move
+    to "real" capsys when we can use fixtures in test methods.
+
+    Once you've used one of these methods, the capturing is reset, so another
+    invocation will only return the delta.
+
+    """
+    @pytest.fixture(autouse=True)
+    def _capcapsys(self, capsys):
+        """Grab the fixture so our methods can use it."""
+        self.capsys = capsys
+
+    def stdouterr(self):
+        """Returns (out, err), two strings for stdout and stderr."""
+        return self.capsys.readouterr()
+
+    def stdout(self):
+        """Returns a string, the captured stdout."""
+        return self.capsys.readouterr().out
+
+    def stderr(self):
+        """Returns a string, the captured stderr."""
+        return self.capsys.readouterr().err