Allow augmenting the variables evaluating string conditions in xfail/…

…skipif markers.

src/_pytest/hookspec.py

@@ -808,6 +808,18 @@ def pytest_warning_recorded(
     """
 
 
+# -------------------------------------------------------------------------
+# Hooks for influencing skipping
+# -------------------------------------------------------------------------
+def pytest_markeval_namespace(config: "Config") -> Dict[str, Any]:
+    """Called when constructing the globals dictionary used for
+    evaluating string conditions in xfail/skipif markers.
+
+    :param _pytest.config.Config config: The pytest config object.
+    :returns: A dictionary of additional globals to add.
+    """
+
+
 # -------------------------------------------------------------------------
 # error handling and internal debugging hooks
 # -------------------------------------------------------------------------

src/_pytest/skipping.py

@@ -3,6 +3,7 @@
 import platform
 import sys
 import traceback
+from collections.abc import Mapping
 from typing import Generator
 from typing import Optional
 from typing import Tuple
@@ -101,6 +102,14 @@ def evaluate_condition(item: Item, mark: Mark, condition: object) -> Tuple[bool,
             "platform": platform,
             "config": item.config,
         }
+        for dictionary in item.ihook.pytest_markeval_namespace(config=item.config):
+            if not isinstance(dictionary, Mapping):
+                raise ValueError(
+                    "pytest_markeval_namespace() needs to return a dict, got {!r}".format(
+                        dictionary
+                    )
+                )
+            globals_.update(dictionary)
         if hasattr(item, "obj"):
             globals_.update(item.obj.__globals__)  # type: ignore[attr-defined]
         try:

testing/test_skipping.py

@@ -1,4 +1,5 @@
 import sys
+import textwrap
 
 import pytest
 from _pytest.pytester import Testdir
@@ -153,6 +154,133 @@ def test_func(self):
         assert skipped
         assert skipped.reason == "condition: config._hackxyz"
 
+    def test_skipif_markeval_namespace(self, testdir):
+        testdir.makeconftest(
+            """
+            import pytest
+
+            def pytest_markeval_namespace():
+                return {"color": "green"}
+            """
+        )
+        p = testdir.makepyfile(
+            """
+            import pytest
+
+            @pytest.mark.skipif("color == 'green'")
+            def test_1():
+                assert True
+
+            @pytest.mark.skipif("color == 'red'")
+            def test_2():
+                assert True
+        """
+        )
+        res = testdir.runpytest(p)
+        assert res.ret == 0
+        res.stdout.fnmatch_lines(["*1 skipped*"])
+        res.stdout.fnmatch_lines(["*1 passed*"])
+
+    def test_skipif_markeval_namespace_multiple(self, testdir):
+        root = testdir.mkdir("root")
+        root.ensure("__init__.py")
+        root.join("conftest.py").write(
+            textwrap.dedent(
+                """\
+            import pytest
+
+            def pytest_markeval_namespace():
+                return {"arg": "root"}
+            """
+            )
+        )
+        root.join("test_root.py").write(
+            textwrap.dedent(
+                """\
+            import pytest
+
+            @pytest.mark.skipif("arg == 'root'")
+            def test_root():
+                assert False
+            """
+            )
+        )
+        foo = root.mkdir("foo")
+        foo.ensure("__init__.py")
+        foo.join("conftest.py").write(
+            textwrap.dedent(
+                """\
+            import pytest
+
+            def pytest_markeval_namespace():
+                return {"arg": "foo"}
+            """
+            )
+        )
+        foo.join("test_foo.py").write(
+            textwrap.dedent(
+                """\
+            import pytest
+
+            @pytest.mark.skipif("arg == 'foo'")
+            def test_foo():
+                assert False
+            """
+            )
+        )
+        bar = root.mkdir("bar")
+        bar.ensure("__init__.py")
+        bar.join("conftest.py").write(
+            textwrap.dedent(
+                """\
+            import pytest
+
+            def pytest_markeval_namespace():
+                return {"arg": "bar"}
+            """
+            )
+        )
+        bar.join("test_bar.py").write(
+            textwrap.dedent(
+                """\
+            import pytest
+
+            @pytest.mark.skipif("arg == 'bar'")
+            def test_bar():
+                assert False
+            """
+            )
+        )
+
+        reprec = testdir.inline_run("-vs", "--capture=no")
+        reprec.assertoutcome(skipped=3)
+
+    def test_skipif_markeval_namespace_ValueError(self, testdir):
+        testdir.makeconftest(
+            """
+            import pytest
+
+            def pytest_markeval_namespace():
+                return True
+            """
+        )
+        p = testdir.makepyfile(
+            """
+            import pytest
+
+            @pytest.mark.skipif("color == 'green'")
+            def test_1():
+                assert True
+        """
+        )
+        res = testdir.runpytest(p)
+        assert res.ret == 1
+        res.stdout.fnmatch_lines(
+            [
+                "*ValueError: pytest_markeval_namespace() needs to return a dict, got True*"
+            ]
+        )
+
 
 class TestXFail:
     @pytest.mark.parametrize("strict", [True, False])
@@ -569,6 +697,33 @@ def test_foo():
         result.stdout.fnmatch_lines(["*1 failed*" if strict else "*1 xpassed*"])
         assert result.ret == (1 if strict else 0)
 
+    def test_skipif_markeval_namespace(self, testdir):
+        testdir.makeconftest(
+            """
+            import pytest
+
+            def pytest_markeval_namespace():
+                return {"color": "green"}
+            """
+        )
+        p = testdir.makepyfile(
+            """
+            import pytest
+
+            @pytest.mark.xfail("color == 'green'")
+            def test_1():
+                assert False
+
+            @pytest.mark.xfail("color == 'red'")
+            def test_2():
+                assert False
+        """
+        )
+        res = testdir.runpytest(p)
+        assert res.ret == 1
+        res.stdout.fnmatch_lines(["*1 failed*"])
+        res.stdout.fnmatch_lines(["*1 xfailed*"])
+
 
 class TestXFailwithSetupTeardown:
     def test_failing_setup_issue9(self, testdir):