test-runner extra now also installs nose, et al.

To make it easier for devs to execute individual tests.

setup.py

@@ -26,6 +26,16 @@
   long_description = f.read()
 
 
+##
+# Declare test dependencies separately, so that they can be installed
+# either automatically (``python setup.py test``) or manually
+# (``pip install -e .[test-runner]``).
+tests_require = [
+  'mock; python_version < "3.0"',
+  'nose',
+]
+
+
 ##
 # Off we go!
 # noinspection SpellCheckingInspection
@@ -67,15 +77,12 @@
   extras_require = {
     'ccurl': ['pyota-ccurl'],
     'docs-builder': ['sphinx', 'sphinx_rtd_theme'],
-    'test-runner': ['detox'],
+    'test-runner': ['detox'] + tests_require,
   },
 
   test_suite    = 'test',
   test_loader   = 'nose.loader:TestLoader',
-  tests_require = [
-    'mock; python_version < "3.0"',
-    'nose',
-  ],
+  tests_require = tests_require,
 
   license = 'MIT',