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Testing FixedSequenceGroup Minimum Value Calculations in LMAX-Disruptor

This test suite validates the FixedSequenceGroup functionality in the LMAX Disruptor library, focusing on sequence group management and minimum value determination. The tests ensure proper handling of multiple sequences and their minimum value calculations.

Test Coverage Overview

The test suite provides comprehensive coverage of the FixedSequenceGroup class, focusing on sequence value management and minimum value determination.

Tests minimum value selection across multiple sequences
Verifies sequence updates and their impact on group values
Covers edge cases with varying sequence values

Implementation Analysis

The testing approach utilizes JUnit Jupiter framework with a clear focus on behavioral verification. The implementation employs assertion-based testing patterns with Hamcrest matchers for precise value comparisons.

Uses Hamcrest CoreMatchers for value assertions
Implements sequential test steps to verify state changes
Employs clear test naming conventions

Technical Details

Test implementation leverages:

JUnit Jupiter test framework
Hamcrest assertion library
Sequence and FixedSequenceGroup classes from Disruptor
Java exception handling for robust testing

Best Practices Demonstrated

The test suite exemplifies several testing best practices including clear test method naming, isolated test scenarios, and explicit assertions.

Single responsibility principle in test methods
Clear setup and verification phases
Descriptive test naming convention
Proper exception handling

lmax-exchange/disruptor

src/test/java/com/lmax/disruptor/FixedSequenceGroupTest.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 FixedSequenceGroupTest
{

    @Test
    public void shouldReturnMinimumOf2Sequences() throws Exception
    {
        Sequence sequence1 = new Sequence(34);
        Sequence sequnece2 = new Sequence(47);
        Sequence group = new FixedSequenceGroup(new Sequence[]{sequence1, sequnece2});

        assertThat(group.get(), is(34L));
        sequence1.set(35);
        assertThat(group.get(), is(35L));
        sequence1.set(48);
        assertThat(group.get(), is(47L));
    }
}