pytest_parametrize_plus was not working correctly with test classes, leading to fixture 'self' not found. Fixed #63

Author: Sylvain MARIE

pytest_cases/main_fixtures.py

@@ -1134,7 +1134,8 @@ def parametrize_plus_decorate(test_func):
             # it is the same than existing, except that we want to replace all parameters with the new fixture
 
             new_sig = remove_signature_parameters(old_sig, *all_param_names)
-            new_sig = add_signature_parameters(new_sig, Parameter(base_name, kind=Parameter.POSITIONAL_OR_KEYWORD))
+            # add it in last position, so that potential 'self' argument (case of test class methods) can stay first
+            new_sig = add_signature_parameters(new_sig, last=Parameter(base_name, kind=Parameter.POSITIONAL_OR_KEYWORD))
 
             # --Finally create the fixture function, a wrapper of user-provided fixture with the new signature
             def replace_paramfixture_with_values(kwargs):

pytest_cases/tests/issues/test_issue_classes.py

@@ -0,0 +1,28 @@
+# test.py
+import pytest
+from pytest_cases import fixture_ref, pytest_parametrize_plus
+
+
+@pytest.fixture
+def foo():
+    return 1
+
+
+@pytest.fixture
+def bar():
+    return 2
+
+
+@pytest_parametrize_plus("arg", [fixture_ref("foo"), fixture_ref("bar")])
+def test_thing(arg):
+    print(arg)
+
+
+class TestCase:
+    @pytest.mark.parametrize("arg", [1, 2])
+    def test_thing_pytest(self, arg):
+        print(arg)
+
+    @pytest_parametrize_plus("arg", [fixture_ref("foo"), fixture_ref("bar")])
+    def test_thing_cases(self, arg):
+        print(arg)