make the sphinxpolicygen extension handle multiple input/output files

Some projects have multiple policy files for different parts of their
API. Make the sample generator extension support this by letting the
policy_generator_config_file option be set to a list of tuples mapping
the config file to the output file base name, as we do in the sample
generator in oslo.config.

Change-Id: I0c7fa409a1ed0f49d65c9b90b71317066f6d3505
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

doc/source/user/sphinxpolicygen.rst

@@ -27,6 +27,11 @@ where:
   source directory (``app.srcdir``). If this option is not specified or is
   invalid then the sample policy file generation will be skipped.
 
+  To handle cases where multiple files need to be generated, this
+  value can be a list of two-part tuples containing the path to the
+  configuration file and the base name for the output file (in this
+  case, ``sample_policy_basename`` should not be set).
+
 ``sample_policy_basename``
   Base name of the output file. This name will be appended with a
   ``.policy.yaml.sample`` extension to generate the final output file and the

oslo_policy/sphinxpolicygen.py

@@ -28,9 +28,19 @@ def generate_sample(app):
                  "skipping sample policy generation")
         return
 
-    _generate_sample(app,
-                     app.config.policy_generator_config_file,
-                     app.config.sample_policy_basename)
+    if isinstance(app.config.policy_generator_config_file, list):
+        for config_file, base_name in app.config.policy_generator_config_file:
+            if base_name is None:
+                base_name = _get_default_basename(config_file)
+            _generate_sample(app, config_file, base_name)
+    else:
+        _generate_sample(app,
+                         app.config.policy_generator_config_file,
+                         app.config.sample_policy_basename)
+
+
+def _get_default_basename(config_file):
+    return os.path.splitext(os.path.basename(config_file))[0]
 
 
 def _generate_sample(app, policy_file, base_name):

oslo_policy/tests/test_sphinxpolicygen.py

@@ -50,3 +50,27 @@ class SingleSampleGenerationTest(base.BaseTestCase):
         sample.assert_called_once_with(args=[
             '--config-file', '/opt/nova/nova.conf',
             '--output-file', '/opt/nova/sample.policy.yaml'])
+
+    @mock.patch('os.path.isdir')
+    @mock.patch('os.path.isfile')
+    @mock.patch('oslo_policy.generator.generate_sample')
+    def test_sample_gen_with_multiple_config_files(self, sample, isfile,
+                                                   isdir):
+        # Tests the scenario that policy_generator_config_file is a list
+        # of two-item tuples of the config file name and policy basename.
+        isfile.side_effect = [False, True] * 2
+        isdir.return_value = True
+
+        config = mock.Mock(policy_generator_config_file=[
+            ('nova.conf', 'nova'),
+            ('placement.conf', 'placement')])
+        app = mock.Mock(srcdir='/opt/nova', config=config)
+        sphinxpolicygen.generate_sample(app)
+
+        sample.assert_has_calls([
+            mock.call(args=[
+                '--config-file', '/opt/nova/nova.conf',
+                '--output-file', '/opt/nova/nova.policy.yaml.sample']),
+            mock.call(args=[
+                '--config-file', '/opt/nova/placement.conf',
+                '--output-file', '/opt/nova/placement.policy.yaml.sample'])])