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Testing MultiProducerSequencer Message Availability in LMAX Disruptor

This test suite validates the MultiProducerSequencer component of the LMAX Disruptor, focusing on message availability and publishing behavior. The tests ensure proper sequencing and availability checks in a multi-producer environment, which is crucial for the high-performance inter-thread messaging system.

Test Coverage Overview

The test suite covers core functionality of the MultiProducerSequencer class, specifically focusing on message availability states.

Validates message publishing sequence
Tests availability checks for published and unpublished messages
Verifies boundary conditions for sequence numbers
Ensures correct behavior of the BlockingWaitStrategy

Implementation Analysis

The testing approach uses JUnit Jupiter framework with focused unit tests that verify discrete functionality. The implementation employs a systematic verification pattern checking both positive and negative cases for message availability.

Uses assertThat with Hamcrest matchers for clear assertions
Implements sequential testing methodology
Utilizes precise boundary testing

Technical Details

Test environment configuration:

JUnit Jupiter testing framework
Hamcrest assertion library
1024-slot sequencer buffer size
BlockingWaitStrategy for sequence coordination
MultiProducerSequencer implementation under test

Best Practices Demonstrated

The test suite exemplifies several testing best practices for high-performance concurrent systems.

Clear test method naming that describes the behavior being tested
Isolated test scenarios with specific assertions
Comprehensive boundary testing
Clean setup with proper initialization
Effective use of assertion libraries for readable tests

lmax-exchange/disruptor

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

            
/*
 * Copyright 2012 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 org.junit.jupiter.api.Test;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;

public class MultiProducerSequencerTest
{
    private final Sequencer publisher = new MultiProducerSequencer(1024, new BlockingWaitStrategy());

    @Test
    public void shouldOnlyAllowMessagesToBeAvailableIfSpecificallyPublished() throws Exception
    {
        publisher.publish(3);
        publisher.publish(5);

        assertThat(publisher.isAvailable(0), is(false));
        assertThat(publisher.isAvailable(1), is(false));
        assertThat(publisher.isAvailable(2), is(false));
        assertThat(publisher.isAvailable(3), is(true));
        assertThat(publisher.isAvailable(4), is(false));
        assertThat(publisher.isAvailable(5), is(true));
        assertThat(publisher.isAvailable(6), is(false));
    }
}