Test for bug #2298: automodule fails to document a class attribute

This test case demonstrates a bug, where automodule:: with option
:members: fails to document a class attribute of a class, that was
imported into the documented module.

This commit extends test_ext_viewcode, instead of creating a separate
test module, because the development guide recommends it for performance
reasons.

tests/roots/test-ext-viewcode/index.rst

@@ -28,6 +28,11 @@ viewcode
    :language: python
    :pyobject: func1
 
+.. autoclass:: spam.mod3.Class3
+   :members:
+
+.. automodule:: spam.mod3
+   :members:
 
 .. toctree::
 

tests/roots/test-ext-viewcode/spam/mod1.py

@@ -13,3 +13,10 @@ class Class1(object):
     """
     this is Class1
     """
+
+class Class3(object):
+    """
+    this is Class3
+    """
+    class_attr = 42
+    """this is the class attribute class_attr"""

tests/roots/test-ext-viewcode/spam/mod3.py

@@ -0,0 +1,2 @@
+from spam.mod1 import Class3
+__all__ = ('Class3',)

tests/test_ext_viewcode.py

@@ -31,6 +31,12 @@ def test_viewcode(app, status, warning):
     assert result.count('href="_modules/spam/mod1.html#Class1"') == 2
     assert result.count('href="_modules/spam/mod2.html#Class2"') == 2
 
+    # test that the class attribute is correctly documented
+    assert result.count('this is Class3') == 2
+    assert 'this is the class attribute class_attr' in result
+    # the next assert fails, until the autodoc bug gets fixed
+    assert result.count('this is the class attribute class_attr') == 2
+
 
 @with_app(testroot='ext-viewcode', tags=['test_linkcode'])
 def test_linkcode(app, status, warning):