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Testing Fatal Exception Handler Implementation in LMAX-Disruptor

This test suite validates the FatalExceptionHandler implementation in the LMAX Disruptor project, focusing on exception handling behavior in concurrent programming scenarios. The tests ensure proper propagation and handling of fatal exceptions in the event processing pipeline.

Test Coverage Overview

The test coverage focuses on validating the FatalExceptionHandler’s core functionality in handling and propagating exceptions.

Verifies runtime exception wrapping of original exceptions
Tests exception cause chain preservation
Validates exception handling for event processing scenarios

Implementation Analysis

The testing approach employs JUnit Jupiter to validate exception handling patterns.

The implementation uses assertThrows to verify exception propagation and assertEquals to validate exception cause relationships. The test demonstrates clean separation of concerns with isolated test scenarios.

Technical Details

Testing infrastructure includes:

JUnit Jupiter test framework
Custom TestEvent support class
FatalExceptionHandler implementation
ExceptionHandler interface integration

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Clear test method naming conventions
Focused test scope with single responsibility
Proper exception handling verification
Effective use of JUnit assertions
Clean and maintainable test structure

lmax-exchange/disruptor

src/test/java/com/lmax/disruptor/FatalExceptionHandlerTest.java

            
/*
 * Copyright 2011 LMAX Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.lmax.disruptor;

import com.lmax.disruptor.support.TestEvent;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;

public final class FatalExceptionHandlerTest
{
    @Test
    public void shouldHandleFatalException()
    {
        final Exception causeException = new Exception();
        final TestEvent event = new TestEvent();

        ExceptionHandler<Object> exceptionHandler = new FatalExceptionHandler();

        Throwable ex =  assertThrows(RuntimeException.class, () -> exceptionHandler.handleEventException(causeException, 0L, event));

        assertEquals(causeException, ex.getCause());
    }
}