Move RequiredEventNotFoundError class to Processor class

tracetools_analysis/test/tracetools_analysis/test_processor.py

@@ -19,7 +19,6 @@ import unittest
 from tracetools_analysis.processor import EventHandler
 from tracetools_analysis.processor import EventMetadata
 from tracetools_analysis.processor import Processor
-from tracetools_analysis.processor import RequiredEventNotFoundError
 
 
 class StubHandler1(EventHandler):
@@ -149,7 +148,7 @@ class TestProcessor(unittest.TestCase):
             'cpu_id': 0,
         }
         # Fails check
-        with self.assertRaises(RequiredEventNotFoundError):
+        with self.assertRaises(Processor.RequiredEventNotFoundError):
             Processor(EventHandlerWithRequiredEvent()).process([mock_event])
 
         required_mock_event = {

tracetools_analysis/tracetools_analysis/processor/__init__.py

@@ -253,13 +253,14 @@ class DependencySolver():
             visited.add(dep_type)
 
 
-class RequiredEventNotFoundError(RuntimeError):
-    pass
-
-
 class Processor():
     """Processor class, which dispatches events to event handlers."""
 
+    class RequiredEventNotFoundError(RuntimeError):
+        """When a trace does not contain one event required by an EventHandler."""
+
+        pass
+
     def __init__(
         self,
         *handlers: EventHandler,
@@ -339,7 +340,7 @@ class Processor():
         for handler in self._expanded_handlers:
             for name in handler.required_events():
                 if name not in event_names:
-                    raise RequiredEventNotFoundError(
+                    raise self.RequiredEventNotFoundError(
                         f'missing event {name} for {handler.__class__.__name__}'
                     )