removes more false positives for unused-argument

pylint_pytest/checkers/fixture.py

@@ -116,10 +116,10 @@ def visit_module(self, node):
                 is_test_module = True
                 break
 
+        stdout, stderr = sys.stdout, sys.stderr
         try:
             with open(os.devnull, "w") as devnull:
                 # suppress any future output from pytest
-                stdout, stderr = sys.stdout, sys.stderr
                 sys.stderr = sys.stdout = devnull
 
                 # run pytest session with customized plugin to collect fixtures
@@ -210,7 +210,7 @@ def visit_functiondef(self, node):
             for arg in node.args.args:
                 self._invoked_with_func_args.add(arg.name)
 
-    # pylint: disable=bad-staticmethod-argument
+    # pylint: disable=bad-staticmethod-argument,too-many-branches # The function itself is an if-return logic.
     @staticmethod
     def patch_add_message(
         self, msgid, line=None, node=None, args=None, confidence=None, col_offset=None
@@ -267,9 +267,18 @@ def patch_add_message(
             msgid == "unused-argument"
             and _can_use_fixture(node.parent.parent)
             and isinstance(node.parent, astroid.Arguments)
-            and node.name in FixtureChecker._pytest_fixtures
         ):
-            return
+            if node.name in FixtureChecker._pytest_fixtures:
+                # argument is used as a fixture
+                return
+
+            fixnames = (
+                arg.name for arg in node.parent.args if arg.name in FixtureChecker._pytest_fixtures
+            )
+            for fixname in fixnames:
+                if node.name in FixtureChecker._pytest_fixtures[fixname][0].argnames:
+                    # argument is used by a fixture
+                    return
 
         # check W0621 redefined-outer-name
         if (

tests/input/unused-argument/func_param_as_fixture_arg.py

@@ -0,0 +1,31 @@
+"""
+This module illustrates a situation in which unused-argument should be
+suppressed, but is not.
+"""
+
+import pytest
+
+
+@pytest.fixture
+def myfix(arg):
+    """A fixture that requests a function param"""
+    print("arg is ", arg)
+    return True
+
+
+@pytest.mark.parametrize("arg", [1, 2, 3])
+def test_myfix(myfix, arg):
+    """A test function that uses the param through a fixture"""
+    assert myfix
+
+
+@pytest.mark.parametrize("narg", [4, 5, 6])
+def test_nyfix(narg):  # unused-argument
+    """A test function that does not use its param"""
+    assert True
+
+
+@pytest.mark.parametrize("arg", [1, 2, 3])
+def test_narg_is_used_nowhere(myfix, narg):
+    """A test function that uses the param through a fixture"""
+    assert myfix

tests/test_unused_argument.py

@@ -29,3 +29,8 @@ def test_caller_not_a_test_func(self, enable_plugin):
     def test_args_and_kwargs(self, enable_plugin):
         self.run_linter(enable_plugin)
         self.verify_messages(2)
+
+    @pytest.mark.parametrize("enable_plugin", [True, False])
+    def test_func_param_as_fixture_arg(self, enable_plugin):
+        self.run_linter(enable_plugin)
+        self.verify_messages(2 if enable_plugin else 3)