Fix pytest.mark.skipif silently ignoring extra keyword arguments

src/_pytest/skipping.py

@@ -174,6 +174,11 @@ def evaluate_skip_marks(item: Item) -> Skip | None:
         else:
             conditions = (mark.kwargs["condition"],)
 
+        for invalid_kwarg in set(mark.kwargs) - {"condition", "reason"}:
+            raise TypeError(
+                f"pytest.mark.skipif() got an unexpected keyword argument {invalid_kwarg!r}"
+            )
+
         # Unconditional.
         if not conditions:
             reason = mark.kwargs.get("reason", "")

testing/test_skipping.py

@@ -61,7 +61,7 @@ def test_marked_one_arg_with_reason(self, pytester: Pytester) -> None:
         item = pytester.getitem(
             """
             import pytest
-            @pytest.mark.skipif("hasattr(os, 'sep')", attr=2, reason="hello world")
+            @pytest.mark.skipif("hasattr(os, 'sep')", reason="hello world")
             def test_func():
                 pass
         """
@@ -882,6 +882,22 @@ def test_hello():
 
 
 class TestSkipif:
+    def test_skipif_invalid_kwarg(self, pytester: Pytester) -> None:
+        p = pytester.makepyfile(
+            """
+            import pytest
+            @pytest.mark.skipif(True, strict=True, reason="")
+            def test_func():
+                pass
+            """
+        )
+        result = pytester.runpytest(p)
+        result.stdout.fnmatch_lines(
+            [
+                "*TypeError: pytest.mark.skipif() got an unexpected keyword argument 'strict'*",
+            ]
+        )
+
     def test_skipif_conditional(self, pytester: Pytester) -> None:
         item = pytester.getitem(
             """