Fix for failing assertion on native modules Issue #1354 (#1370)

AUTHORS.txt

@@ -52,5 +52,6 @@ Tobias Rzepka (@TobiasRzepka)
 micbou (@micbou)
 Dima Gerasimov (@karlicoss) <karlicoss@gmail.com>
 Max Woerner Chase (@mwchase) <max.chase@gmail.com>
+Johannes Maria Frank (@jmfrank63) <jmfrank63@gmail.com>
 
 Note: (@user) means a github user name.

jedi/evaluate/gradual/conversion.py

@@ -40,7 +40,9 @@ def _stub_to_python_context_set(stub_context, ignore_compiled=False):
 
 
 def _infer_from_stub(stub_module, qualified_names, ignore_compiled):
-    assert isinstance(stub_module, StubModuleContext), stub_module
+    from jedi.evaluate.compiled.mixed import MixedObject
+    assert isinstance(stub_module, StubModuleContext) or \
+           isinstance(stub_module, MixedObject), stub_module
     non_stubs = stub_module.non_stub_context_set
     if ignore_compiled:
         non_stubs = non_stubs.filter(lambda c: not c.is_compiled())

test/test_api/test_interpreter.py

@@ -8,7 +8,7 @@ import pytest
 import jedi
 from jedi._compatibility import is_py3, py_version
 from jedi.evaluate.compiled import mixed
-
+from importlib import import_module
 
 if py_version > 30:
     def exec_(source, global_map):
@@ -439,3 +439,9 @@ def test__wrapped__():
     c, = jedi.Interpreter('syslogs_to_df', [locals()]).completions()
     # Apparently the function starts on the line where the decorator starts.
     assert c.line == syslogs_to_df.__wrapped__.__code__.co_firstlineno + 1
+
+@pytest.mark.parametrize('module_name', ['sys', 'time'])
+def test_core_module_completes(module_name):
+    module = import_module(module_name)
+    assert jedi.Interpreter(module_name + '.\n', [locals()]).completions()
+