Give slightly more information when definition is invalid

Because it now fails at the assertion inside assertIsDefinitionValid, it'll show the information at that point in the stack, rather than showing that the entire function returned False which could be a lot of things (if you don't actually go reading the function because then you discovered that it could only be one thing).

tests/Settings/TestDefinitionContainer.py

@@ -36,15 +36,14 @@ def test_validateMachineDefinitionContainer(file_name, definition_container):
         return  # Stop checking, these are root files.
 
     definition_path = os.path.join(os.path.dirname(__file__), "..", "..", "resources", "definitions")
-    assert isDefinitionValid(definition_container, definition_path, file_name)
+    assertIsDefinitionValid(definition_container, definition_path, file_name)
 
 
-def isDefinitionValid(definition_container, path, file_name):
+def assertIsDefinitionValid(definition_container, path, file_name):
     with open(os.path.join(path, file_name), encoding = "utf-8") as data:
         json = data.read()
         parser, is_valid = definition_container.readAndValidateSerialized(json)
-        if not is_valid:
-            print("The definition '{0}', has invalid data.".format(file_name))
+        assert is_valid #The definition has invalid JSON structure.
         metadata = DefinitionContainer.deserializeMetadata(json, "whatever")
 
         # If the definition defines a platform file, it should be in /resources/meshes/
@@ -52,6 +51,4 @@ def isDefinitionValid(definition_container, path, file_name):
             assert metadata[0]["platform"] in all_meshes
 
         if "platform_texture" in metadata[0]:
-            assert metadata[0]["platform_texture"] in all_images
-
-        return is_valid
+            assert metadata[0]["platform_texture"] in all_images