Declare test dependencies in [test] extra (#251)

Also introduce a constraints file to handle Python 2 in CI.

.github/workflows/ci.yaml

@@ -27,12 +27,7 @@ jobs:
           python-version: ${{matrix.python}}
       - name: Install dependencies
         run: |
-          if test ${{matrix.python}} = 2.7; then
-            python -m pip install pyparsing==2.4.7 'PyYAML<6.0'
-          fi
-          python -m pip install --upgrade pip setuptools
-          python -m pip install mock pytest pytest-cov
-          python setup.py build develop
+          python -m pip install -U -e .[test] pytest-cov -c constraints.txt
       - name: Run tests
         run: |
           python -m pytest --cov test

constraints.txt

@@ -0,0 +1,2 @@
+pyparsing==2.4.7; python_version < '3'
+PyYAML<6.0; python_version < '3'

setup.py

@@ -24,6 +24,11 @@
         'console_scripts': ['rosversion=rospkg.rosversion:main'],
     },
     'install_requires': install_requires,
+    'extras_require': {
+        'test': [
+            "mock; python_version < '3.3'",
+            'pytest',
+        ]},
     'author': 'Ken Conley',
     'author_email': '[email protected]',
     'url': 'http://wiki.ros.org/rospkg',