Add an additional test to check inter-dependencies.

tests/fixtures/foo_requirement/setup.py

@@ -0,0 +1,18 @@
+from setuptools import setup
+
+setup_options = dict(
+    name='foo_requirement',
+    version='0.1.0dev',
+    author='Kyle Gibson',
+    author_email='kyle.gibson@frozenonline.com',
+    description='Another test requirement fixture',
+    license='BSD',
+    url='',
+    packages=['foo_requirement'],
+    long_description='',
+    install_requires=['test_requirement'],
+    classifiers=[],
+    zip_safe=False,
+)
+
+setup(**setup_options)

tests/tests.py

@@ -257,6 +257,21 @@ def test_install_with_requirement(self):
         expected = ['test_requirement']
         self.assertEqual(actual, expected)
 
+    def test_install_with_dependency(self):
+        # Verify that a requirement can be used after it is installed
+        self._add_requirements(
+            self._get_path('fixtures', 'test_requirement'),
+            self._get_path('fixtures', 'foo_requirement'),
+        )
+        self.assertInstall()
+        # Include a negative test as a control
+        actual = self._can_import_requirements(
+            'test_requirement',
+            'foo_requirements',  # should not exist
+        )
+        expected = ['test_requirement', 'foo_requirement']
+        self.assertEqual(actual, expected)
+
     def test_install_with_requirement_comments(self):
         # Verify that a requirement file with comment lines can be used.
         self._add_requirements(