Add compatibility function to assert outcomes

requirements-testing.txt

@@ -1 +1 @@
-mock
+packaging

tests/utils.py

@@ -0,0 +1,46 @@
+from __future__ import absolute_import, unicode_literals
+
+import pytest
+from packaging.utils import Version
+
+PYTEST_VERSION = Version(pytest.__version__)
+
+_errors_key = "error" if PYTEST_VERSION < Version("6") else "errors"
+
+if PYTEST_VERSION < Version("6"):
+
+    def assert_outcomes(
+        result,
+        passed=0,
+        skipped=0,
+        failed=0,
+        errors=0,
+        xpassed=0,
+        xfailed=0,
+    ):
+        """Compatibility function for result.assert_outcomes"""
+        return result.assert_outcomes(
+            error=errors,  # Pytest < 6 uses the singular form
+            passed=passed,
+            skipped=skipped,
+            failed=failed,
+            xpassed=xpassed,
+            xfailed=xfailed,
+        )
+
+
+else:
+
+    def assert_outcomes(
+        result,
+        passed=0,
+        skipped=0,
+        failed=0,
+        errors=0,
+        xpassed=0,
+        xfailed=0,
+    ):
+        """Compatibility function for result.assert_outcomes"""
+        return result.assert_outcomes(
+            errors=errors, passed=passed, skipped=skipped, failed=failed, xpassed=xpassed, xfailed=xfailed
+        )