Get some pytest fixtures working with some side effects

jedi/plugins/pytest.py

@@ -0,0 +1,62 @@
+from jedi._compatibility import FileNotFoundError
+from jedi.inference.cache import inference_state_method_cache
+from jedi.inference.imports import load_module_from_path
+from jedi.inference.filters import ParserTreeFilter
+from jedi.inference.base_value import NO_VALUES, ValueSet
+
+
+def execute(callback):
+    def wrapper(value, arguments):
+        if value.py__name__() == 'fixture' \
+                and value.parent_context.py__name__() == '_pytest.fixtures':
+            return NO_VALUES
+
+        return callback(value, arguments)
+    return wrapper
+
+
+def infer_anonymous_param(func):
+    def get_returns(value):
+        function_context = value.as_context()
+        return function_context.get_return_values()
+
+    def wrapper(param):
+        module = param.get_root_context()
+        fixtures = _goto_pytest_fixture(module, param.string_name)
+        if fixtures:
+            return ValueSet.from_sets(
+                get_returns(value)
+                for fixture in fixtures
+                for value in fixture.infer()
+            )
+        return func(param)
+    return wrapper
+
+
+def _goto_pytest_fixture(module_context, name):
+    for module_context in _iter_pytest_modules(module_context):
+        names = FixtureFilter(module_context).get(name)
+        if names:
+            return names
+
+
+@inference_state_method_cache()
+def _iter_pytest_modules(module_context):
+    yield module_context
+
+    folder = module_context.get_value().file_io.get_parent_folder()
+    sys_path = module_context.inference_state.get_sys_path()
+    while any(folder.path.startswith(p) for p in sys_path):
+        file_io = folder.get_file_io('conftest.py')
+        try:
+            m = load_module_from_path(module_context.inference_state, file_io)
+            yield m.as_context()
+        except FileNotFoundError:
+            pass
+        folder = folder.get_parent_folder()
+
+
+class FixtureFilter(ParserTreeFilter):
+    def _filter(self, names):
+        for name in super(FixtureFilter, self)._filter(names):
+            yield name