Change CLI arguments

Allow the database connection string to be pulled from an envvar.

carbon/cli.py

@@ -9,19 +9,21 @@
 
 @click.command()
 @click.version_option()
-@click.argument('db')
 @click.argument('feed_type', type=click.Choice(['people', 'articles']))
+@click.option('--db', envvar='CARBON_DB', help='Database connection string')
 @click.option('-o', '--out', help='Output file', type=click.File('wb'),
               default='-')
-def main(db, feed_type, out):
+def main(feed_type, db, out):
     """Generate feeds for Symplectic Elements.
 
-    The data is pulled from a database identified by DB, which should
-    be a valid SQLAlchemy database connection string. For oracle use:
+    The data is pulled from a database identified by --db, which should
+    be a valid SQLAlchemy database connection string. This can also be
+    omitted and pulled from an environment variable named CARBON_DB. For
+    oracle use:
 
     oracle://<username>:<password>@<server>:1521/<sid>
 
-    The feed will be printed to stdout if OUT is not specified.
+    The feed will be printed to stdout if -o/--out is not specified.
 
     FEED_TYPE should be 'people' or 'articles'.
     """

tests/test_cli.py

@@ -17,14 +17,14 @@ def runner():
 
 
 def test_people_returns_people(runner, xml_data):
-    res = runner.invoke(main, ['sqlite://', 'people'])
+    res = runner.invoke(main, ['--db', 'sqlite://', 'people'])
     assert res.exit_code == 0
     assert res.output_bytes == \
         ET.tostring(xml_data, encoding="UTF-8", xml_declaration=True)
 
 
 def test_articles_returns_articles(runner, articles_data):
-    res = runner.invoke(main, ['sqlite://', 'articles'])
+    res = runner.invoke(main, ['--db', 'sqlite://', 'articles'])
     assert res.exit_code == 0
     assert res.output_bytes == \
         ET.tostring(articles_data, encoding='UTF-8', xml_declaration=True)