Add a test that checks for mixed upper and lower case letters

in pip show
Remove useless import in stubs for named tests

tests/data/src/required_by_mixed_capitalization/required_by_mixed_capitalization/__init__.py

@@ -0,0 +1 @@
+#

tests/data/src/required_by_mixed_capitalization/setup.py

@@ -0,0 +1,6 @@
+from setuptools import setup
+
+setup(name='requires_Capitalized',
+      version='0.1',
+      install_requires=['simple==1.0']
+      )

tests/data/src/requires_capitalized/setup.py

@@ -1,4 +1,4 @@
-from setuptools import find_packages, setup
+from setuptools import setup
 
 setup(name='Requires_Capitalized',
       version='0.1',

tests/functional/test_show.py

@@ -236,3 +236,21 @@ def test_show_required_by_packages_capitalized(script, data):
 
     assert 'Name: simple' in lines
     assert 'Required-by: Requires-Capitalized' in lines
+
+
+def test_show_required_by_with_mixed_capitalization(script, data):
+    """
+    Test that installed packages that depend on this package are shown
+    where the package requires a name with a mix of
+    lower and upper case letters
+    """
+    editable_path = os.path.join(data.src, 'required_by_mixed_capitalization')
+    script.pip(
+        'install', '--no-index', '-f', data.find_links, editable_path
+    )
+
+    result = script.pip('show', 'Requires_CapitalizeD')
+    lines = result.stdout.splitlines()
+
+    assert 'Name: Requires-Capitalized' in lines
+    assert 'Required-by: simple' in lines