Support xfailed and xpassed outcomes in RunResult.

AUTHORS

@@ -213,6 +213,7 @@ Vitaly Lashmanov
 Vlad Dragos
 Wil Cooley
 William Lee
+Wim Glenn
 Wouter van Ackooy
 Xuan Luong
 Xuecong Liao

changelog/3837.feature.rst

@@ -0,0 +1 @@
+Added support for 'xfailed' and 'xpassed' outcomes to the ``pytester.RunResult.assert_outcomes`` signature.

src/_pytest/pytester.py

@@ -406,7 +406,9 @@ def parseoutcomes(self):
                     return d
         raise ValueError("Pytest terminal report not found")
 
-    def assert_outcomes(self, passed=0, skipped=0, failed=0, error=0):
+    def assert_outcomes(
+        self, passed=0, skipped=0, failed=0, error=0, xpassed=0, xfailed=0
+    ):
         """Assert that the specified outcomes appear with the respective
         numbers (0 means it didn't occur) in the text output from a test run.
 
@@ -417,10 +419,18 @@ def assert_outcomes(self, passed=0, skipped=0, failed=0, error=0):
             "skipped": d.get("skipped", 0),
             "failed": d.get("failed", 0),
             "error": d.get("error", 0),
+            "xpassed": d.get("xpassed", 0),
+            "xfailed": d.get("xfailed", 0),
         }
-        assert obtained == dict(
-            passed=passed, skipped=skipped, failed=failed, error=error
-        )
+        expected = {
+            "passed": passed,
+            "skipped": skipped,
+            "failed": failed,
+            "error": error,
+            "xpassed": xpassed,
+            "xfailed": xfailed,
+        }
+        assert obtained == expected
 
 
 class CwdSnapshot(object):

testing/test_pytester.py

@@ -83,6 +83,57 @@ def test_hello(testdir):
     result.assert_outcomes(passed=1)
 
 
+def test_runresult_assertion_on_xfail(testdir):
+    testdir.makepyfile(
+        """
+        import pytest
+
+        pytest_plugins = "pytester"
+
+        @pytest.mark.xfail
+        def test_potato():
+            assert False
+    """
+    )
+    result = testdir.runpytest()
+    result.assert_outcomes(xfailed=1)
+    assert result.ret == 0
+
+
+def test_runresult_assertion_on_xpassed(testdir):
+    testdir.makepyfile(
+        """
+        import pytest
+
+        pytest_plugins = "pytester"
+
+        @pytest.mark.xfail
+        def test_potato():
+            assert True
+    """
+    )
+    result = testdir.runpytest()
+    result.assert_outcomes(xpassed=1)
+    assert result.ret == 0
+
+
+def test_xpassed_with_strict_is_considered_a_failure(testdir):
+    testdir.makepyfile(
+        """
+        import pytest
+
+        pytest_plugins = "pytester"
+
+        @pytest.mark.xfail(strict=True)
+        def test_potato():
+            assert True
+    """
+    )
+    result = testdir.runpytest()
+    result.assert_outcomes(failed=1)
+    assert result.ret != 0
+
+
 def make_holder():
     class apiclass(object):
         def pytest_xyz(self, arg):