Add tests for Engine exception handling

tests/server/test_engine_handle_exception.py

@@ -0,0 +1,86 @@
+import asyncio
+from unittest import mock
+
+import pytest
+
+from protean.domain import Domain
+from protean.server.engine import Engine
+
+
+@pytest.fixture
+def engine():
+    domain = Domain(__file__, load_toml=False)
+    return Engine(domain, test_mode=True, debug=True)
+
+
+def test_handle_exception_with_exception(engine):
+    loop = engine.loop
+
+    async def faulty_task():
+        raise Exception("Test exception")
+
+    with mock.patch.object(engine, "shutdown") as mock_shutdown, mock.patch(
+        "traceback.print_stack"
+    ) as mock_print_stack, mock.patch(
+        "protean.server.engine.logger.error"
+    ) as mock_logger_error:
+        # Start the engine in a separate coroutine
+        async def run_engine():
+            loop.create_task(faulty_task())
+            engine.run()
+
+        # Run the engine and handle the exception
+        loop.run_until_complete(run_engine())
+
+        # Ensure the logger captured the exception message
+        mock_logger_error.assert_any_call("Caught exception: Test exception")
+        mock_print_stack.assert_called_once()
+        mock_shutdown.assert_called_once_with(exit_code=1)
+
+
+def test_handle_exception_without_exception(engine):
+    loop = engine.loop
+
+    async def faulty_task():
+        raise Exception("Test exception without exception in context")
+
+    with mock.patch.object(engine, "shutdown") as mock_shutdown, mock.patch(
+        "protean.server.engine.logger.error"
+    ) as mock_logger_error:
+        # Create a faulty task without an exception in the context
+        async def run_engine():
+            faulty_context = {"message": "Test message"}
+            loop.call_exception_handler(faulty_context)
+            engine.run()
+
+        # Run the engine
+        loop.run_until_complete(run_engine())
+
+        mock_logger_error.assert_any_call("Caught exception: Test message")
+        mock_shutdown.assert_not_called()
+
+
+def test_handle_exception_while_running(engine):
+    loop = engine.loop
+
+    async def faulty_task():
+        raise Exception("Test exception while running")
+
+    with mock.patch.object(engine, "shutdown") as mock_shutdown, mock.patch(
+        "traceback.print_stack"
+    ) as mock_print_stack, mock.patch(
+        "protean.server.engine.logger.error"
+    ) as mock_logger_error:
+        # Run the engine with a faulty task that raises an exception
+        async def run_engine():
+            loop.create_task(faulty_task())
+            engine.run()
+
+        # Run the engine
+        loop.run_until_complete(run_engine())
+
+        mock_logger_error.assert_any_call(
+            "Caught exception: Test exception while running"
+        )
+        mock_print_stack.assert_called_once()
+        mock_shutdown.assert_called_once_with(exit_code=1)