strip comments from requirements

as explained by @aelgru requirements.txt files may contain comments so
these need to be ignored. Inline comments are not handled right now, I
don't know if these are allowed or not.

src/main/python/pybuilder/plugins/python/distutils_plugin.py

@@ -190,12 +190,20 @@ def build_binary_distribution(project, logger):
                     "Error while executing setup command %s", command)
 
 
-def flatten(requirements_file):
+def strip_comments(requirements):
+    return [requirement for requirement in requirements
+            if not requirement.strip().startswith("#")]
+
+
+def quote(requirements):
+    return ['"%s"' % requirement for requirement in requirements]
+
+
+def flatten_and_quote(requirements_file):
     with open(requirements_file.name, 'r') as requirements_file:
         requirements = [d.strip("\n") for d in requirements_file.readlines()]
         requirements = [d for d in requirements if d]
-        quoted_requirements = ['"%s"' % requirement for requirement in requirements]
-        return quoted_requirements
+        return quote(strip_comments(requirements))
 
 
 def format_single_dependency(dependency):
@@ -214,7 +222,7 @@ def build_install_dependencies_string(project):
         return ""
 
     dependencies = [format_single_dependency(dependency) for dependency in dependencies]
-    requirements = [flatten(requirement) for requirement in requirements]
+    requirements = [strip_comments(flatten_and_quote(requirement)) for requirement in requirements]
     flattened_requirements = [dependency for dependency_list in requirements for dependency in dependency_list]
 
     dependencies.extend(flattened_requirements)

src/unittest/python/plugins/python/distutils_plugin_tests.py

@@ -74,6 +74,46 @@ def test_should_not_insert_default_version_operator_when_project_contains_operat
         self.assertEqual(
             'install_requires = [ "spam==0.7" ],', build_install_dependencies_string(self.project))
 
+    @patch("pybuilder.plugins.python.distutils_plugin.open", create=True)
+    def test_should_quote_requirements(self, mock_open):
+        mock_open.return_value = MagicMock(spec=TYPE_FILE)
+        handle = mock_open.return_value.__enter__.return_value
+        handle.readlines.return_value = ["foo", "bar"]
+        self.project.depends_on_requirements("requirements.txt")
+
+        self.assertEqual(
+            'install_requires = [ "foo", "bar" ],', build_install_dependencies_string(self.project))
+
+    @patch("pybuilder.plugins.python.distutils_plugin.open", create=True)
+    def test_should_ignore_empty_requirement_lines(self, mock_open):
+        mock_open.return_value = MagicMock(spec=TYPE_FILE)
+        handle = mock_open.return_value.__enter__.return_value
+        handle.readlines.return_value = ["", "foo", "bar"]
+        self.project.depends_on_requirements("requirements.txt")
+
+        self.assertEqual(
+            'install_requires = [ "foo", "bar" ],', build_install_dependencies_string(self.project))
+
+    @patch("pybuilder.plugins.python.distutils_plugin.open", create=True)
+    def test_should_ignore_comments_from_requirements(self, mock_open):
+        mock_open.return_value = MagicMock(spec=TYPE_FILE)
+        handle = mock_open.return_value.__enter__.return_value
+        handle.readlines.return_value = ["#comment", "bar"]
+        self.project.depends_on_requirements("requirements.txt")
+
+        self.assertEqual(
+            'install_requires = [ "bar" ],', build_install_dependencies_string(self.project))
+
+    @patch("pybuilder.plugins.python.distutils_plugin.open", create=True)
+    def test_should_ignore_comments_with_leading_space_from_requirements(self, mock_open):
+        mock_open.return_value = MagicMock(spec=TYPE_FILE)
+        handle = mock_open.return_value.__enter__.return_value
+        handle.readlines.return_value = [" # comment", "bar"]
+        self.project.depends_on_requirements("requirements.txt")
+
+        self.assertEqual(
+            'install_requires = [ "bar" ],', build_install_dependencies_string(self.project))
+
 
 class DependencyLinksTest(unittest.TestCase):