Add a summary property to ValidationError exceptions

Signed-off-by: Aurélien Bompard <aurelien@bompard.org>

fedora_messaging/exceptions.py

@@ -1,5 +1,7 @@
 """Exceptions raised by Fedora Messaging."""
 
+import jsonschema
+
 
 class BaseException(Exception):
     """The base class for all exceptions raised by fedora_messaging."""
@@ -182,3 +184,11 @@ class ValidationError(BaseException):
     and testing that you're trying to publish a message with a different
     format, and that you should either fix it or update the schema.
     """
+
+    @property
+    def summary(self):
+        """A short summary of the error."""
+        original_exception = self.args[0]
+        if isinstance(original_exception, jsonschema.exceptions.ValidationError):
+            return original_exception.message
+        return str(original_exception)

news/+validation-summary.feature

@@ -0,0 +1 @@
+Add a `summary` property to `ValidationError` exceptions

tests/unit/test_message.py

@@ -46,8 +46,9 @@ def test_invalid_severity(self):
         msg = message.Message()
         msg._headers["fedora_messaging_severity"] = 42
 
-        with pytest.raises(exceptions.ValidationError):
+        with pytest.raises(exceptions.ValidationError) as excinfo:
             message.get_message("", msg._properties, b"{}")
+        assert excinfo.value.summary == "42 is not one of [10, 20, 30, 40]"
 
     def test_missing_headers(self):
         """Assert missing headers results in a default message."""
@@ -140,8 +141,9 @@ def test_proper_message_multiple(self):
     def test_improper_messages(self):
         """Assert TypeError is raised when improper messages are provided"""
         messages = ["m1", "m2"]
-        with pytest.raises(exceptions.ValidationError):
+        with pytest.raises(exceptions.ValidationError) as excinfo:
             message.dumps(messages)
+        assert excinfo.value.summary == "'str' object has no attribute 'validate'"
 
 
 class TestMessageLoads: