Tests for invalid parameter files

-Tests warnings for missing and empty parameter files.
-Tests warnings when rest_parameter stanza lists
parameter file but no parameters.

Change-Id: Ic2c740a34964b1e23560102cc4e5c7fe0be63d50

os_api_ref/__init__.py

@@ -203,11 +203,11 @@ class RestParametersDirective(Table):
         if fpath in YAML_CACHE:
             return YAML_CACHE[fpath]
 
+        lookup = {}
         # self.app.info("Fpath: %s" % fpath)
         try:
             with open(fpath, 'r') as stream:
                 lookup = ordered_load(stream)
-                self._check_yaml_sorting(fpath, lookup)
         except IOError:
             self.env.warn(
                 self.env.docname,
@@ -217,6 +217,14 @@ class RestParametersDirective(Table):
             self.app.warn(exc)
             raise
 
+        if lookup:
+            self._check_yaml_sorting(fpath, lookup)
+        else:
+            self.env.warn(
+                self.env.docname,
+                "Parameters file is empty %s" % fpath)
+            return
+
         YAML_CACHE[fpath] = lookup
         return lookup
 
@@ -272,7 +280,10 @@ class RestParametersDirective(Table):
         This allows use to reference an external file for the actual
         parameter definitions.
         """
+
         lookup = self._load_param_file(fpath)
+        if not lookup:
+            return
 
         content = "\n".join(self.content)
         parsed = yaml.load(content)

os_api_ref/tests/examples/warnings/empty_parameters_file.yaml

@@ -0,0 +1 @@
+# Empty parameter file

os_api_ref/tests/examples/warnings/index.rst

@@ -14,3 +14,24 @@ I am text, hear me roar!
    - name: lookup_key_name
    - name: name_1
    - invalid_name
+
+
+No Parameters Specified
+-----------------------
+
+.. rest_parameters:: parameters.yaml
+
+
+
+Empty File and Parameters Specified
+-----------------------------------
+
+.. rest_parameters:: empty_parameters_file.yaml
+
+   - name: name
+
+Nonexistent Parameter File
+--------------------------
+
+.. rest_parameters:: no_parameters.yaml
+

os_api_ref/tests/test_warnings.py

@@ -52,7 +52,7 @@ class TestWarnings(base.TestCase):
             self.warning)
 
     def test_missing_lookup_name(self):
-        """Warning when missing lookup key in parameter file."""
+        """Warning when missing a lookup key in parameter file."""
         self.assertIn(
             ("WARNING: No field definition for ``lookup_key_name`` found in "),
             self.warning)
@@ -73,3 +73,23 @@ class TestWarnings(base.TestCase):
             ("WARNING: Invalid parameter definition ``invalid_name``. "
              + "Expected format: ``name: reference``. "),
             self.warning)
+
+    def test_empty_parameter_file(self):
+        """Warning when parameter file exists but is empty."""
+        self.assertIn(
+            ("WARNING: Parameters file is empty"),
+            self.warning)
+
+    def test_no_parameters_set(self):
+        """Error when parameters are not set in rest_parameters stanza."""
+        self.assertIn(
+            ("ERROR: No parameters defined\n\n.."
+             + " rest_parameters:: parameters.yaml\n"),
+            self.warning)
+
+    def test_parameter_file_not_exist(self):
+        """Error when parameter file does not exist"""
+        self.assertIn(
+            ("ERROR: No parameters defined\n\n.."
+             + " rest_parameters:: no_parameters.yaml\n"),
+            self.warning)