Handle unittest.SkipTest during collection as error (#10821)

src/_pytest/runner.py

@@ -409,8 +409,6 @@ def collect() -> list[Item | Collector]:
     else:
         skip_exceptions = [Skipped]
         unittest = sys.modules.get("unittest")
-        if unittest is not None:
-            skip_exceptions.append(unittest.SkipTest)
         if isinstance(call.excinfo.value, tuple(skip_exceptions)):
             outcome = "skipped"
             r_ = collector._repr_failure_py(call.excinfo, "line")

testing/test_unittest.py

@@ -1718,3 +1718,25 @@ def abstract2(self): pass
     result = pytester.runpytest()
     assert result.ret == ExitCode.OK
     result.assert_outcomes(passed=1)
+
+
+def test_unittest_skip_alias_misuse_fails(pytester):
+    pytester.makepyfile(
+        """
+        import unittest
+
+        broken = unittest.skip("broken")
+
+        class MyTests(unittest.TestCase):
+            @broken
+            def test_good(self):
+                assert True
+
+            @broken("bar")
+            def test_bad(self):
+                assert False
+        """
+    )
+
+    result = pytester.runpytest()
+    result.assert_outcomes(errors=1, skipped=0)