removes more false positives for unused-argument

pylint_pytest/checkers/fixture.py

@@ -110,10 +110,10 @@ 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
@@ -238,11 +238,16 @@ def patch_add_message(self, msgid, line=None, node=None, args=None,
                     return
 
         # check W0613 unused-argument
-        if 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 msgid == 'unused-argument':
+            if _can_use_fixture(node.parent.parent):
+                if isinstance(node.parent, astroid.Arguments):
+                    if node.name in FixtureChecker._pytest_fixtures:
+                        return  # argument is used as a fixture
+                    else:
+                        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:
+                                return  # argument is used by a fixture
 
         # check W0621 redefined-outer-name
         if msgid == 'redefined-outer-name' and \

tests/input/unused-argument/func_param_as_fixture_arg.py

@@ -0,0 +1,24 @@
+"""
+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

tests/test_unused_argument.py

@@ -28,3 +28,8 @@ 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(1 if enable_plugin else 2)