Disallow non-unique instance names for platforms (ansible#1775)

If we do not put this validation in place then Molecule does key merging
on the Python layer and the end-user can end with less instances than
they might hope for without knowing why.

References:

  pyeve/cerberus#467

Signed-off-by: Luke Murphy <[email protected]>

molecule/model/schema_v2.py

@@ -18,15 +18,15 @@
 # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 # DEALINGS IN THE SOFTWARE.
 
+import collections
 import copy
 import functools
 import re
 
 import cerberus
 import cerberus.errors
 
-from molecule import interpolation
-from molecule import util
+from molecule import interpolation, util
 
 
 def coerce_env(env, keep_string, v):
@@ -269,6 +269,8 @@ def pre_validate_base_schema(env, keep_string):
  'name': {
  'type': 'string',
  'required': True,
+ 'unique': # https://github.com/pyeve/cerberus/issues/467
+ True,
  },
  'groups': {
  'type': 'list',
@@ -944,6 +946,20 @@ class Validator(cerberus.Validator):
  def __init__(self, *args, **kwargs):
  super(Validator, self).__init__(*args, **kwargs)
 
+ def _validate_unique(self, unique, field, value):
+ """Ensure value uniqueness.
+
+ The rule's arguments are validated against this schema:
+ {'type': 'boolean'}
+ """
+ if unique:
+ root_key = self.schema_path[0]
+ data = (doc[field] for doc in self.root_document[root_key])
+ for key, count in collections.Counter(data).items():
+ if count > 1:
+ msg = "'{}' is not unique".format(key)
+ self._error(field, msg)
+
  def _validate_disallowed(self, disallowed, field, value):
  """ Readonly but with a custom error.
 

test/unit/model/v2/test_platforms_section.py

@@ -115,6 +115,28 @@ def test_platforms_docker(_config):
  assert {} == schema_v2.validate(_config)
 
 
+@pytest.mark.parametrize(
+ '_config', ['_model_platforms_docker_section_data'], indirect=True)
+def test_platforms_unique_names(_config):
+ instance_name = _config['platforms'][0]['name']
+ _config['platforms'] += [{
+ 'name': instance_name # duplicate platform name
+ }]
+
+ expected_validation_errors = {
+ 'platforms': [{
+ 0: [{
+ 'name': ["'{}' is not unique".format(instance_name)]
+ }],
+ 1: [{
+ 'name': ["'{}' is not unique".format(instance_name)]
+ }]
+ }]
+ }
+
+ assert expected_validation_errors == schema_v2.validate(_config)
+
+
 @pytest.fixture
 def _model_platforms_docker_errors_section_data():
  return {