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Validating CodaHale Metrics Cleanup Operations in HikariCP

A comprehensive test suite for validating the CodaHale metrics tracking functionality in HikariCP’s connection pool management system. This test suite focuses on verifying proper cleanup and removal of metrics when the tracker is closed, ensuring resource management and monitoring capabilities work as expected.

Test Coverage Overview

The test suite provides targeted coverage for the metrics cleanup process in HikariCP’s connection pool monitoring system.

Key areas tested include:

Verification of metric removal for connection pool statistics
Validation of cleanup for both active and idle connection metrics
Testing of connection timeout and creation timing metrics
Confirmation of proper resource cleanup for pool sizing metrics

Implementation Analysis

The implementation utilizes Mockito for mocking the MetricRegistry, allowing isolated testing of the metrics cleanup functionality. The testing approach employs the AAA (Arrange-Act-Assert) pattern with a clear setup phase using @Before and verification of multiple metric removals in the test method.

Technical implementation details:

MockitoJUnitRunner for automatic mock initialization
StubPoolStats for simulating pool statistics
Verification of multiple metric removal calls

Technical Details

Testing tools and configuration:

JUnit 4 testing framework
Mockito mocking framework
Custom StubPoolStats implementation
MetricRegistry mock for verification
CodaHale Metrics integration
Test setup using dependency injection via constructor

Best Practices Demonstrated

The test suite exemplifies several testing best practices in Java unit testing. It demonstrates clean separation of concerns, proper mock usage, and thorough verification of cleanup operations.

Notable practices include:

Clear test method naming and organization
Proper setup isolation using @Before
Comprehensive verification of all metric removal operations
Use of mocking to isolate test dependencies
Clean and maintainable test structure

brettwooldridge/hikaricp

src/test/java/com/zaxxer/hikari/metrics/dropwizard/CodaHaleMetricsTrackerTest.java

            
package com.zaxxer.hikari.metrics.dropwizard;

import com.codahale.metrics.MetricRegistry;
import com.zaxxer.hikari.mocks.StubPoolStats;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.junit.MockitoJUnitRunner;

import static org.mockito.Mockito.verify;

@RunWith(MockitoJUnitRunner.class)
public class CodaHaleMetricsTrackerTest
{

   @Mock
   public MetricRegistry mockMetricRegistry;

   private CodaHaleMetricsTracker testee;

   @Before
   public void setup()
   {
      testee = new CodaHaleMetricsTracker("mypool", new StubPoolStats(0), mockMetricRegistry);
   }

   @Test
   public void close()
   {
      testee.close();

      verify(mockMetricRegistry).remove("mypool.pool.Wait");
      verify(mockMetricRegistry).remove("mypool.pool.Usage");
      verify(mockMetricRegistry).remove("mypool.pool.ConnectionCreation");
      verify(mockMetricRegistry).remove("mypool.pool.ConnectionTimeoutRate");
      verify(mockMetricRegistry).remove("mypool.pool.TotalConnections");
      verify(mockMetricRegistry).remove("mypool.pool.IdleConnections");
      verify(mockMetricRegistry).remove("mypool.pool.ActiveConnections");
      verify(mockMetricRegistry).remove("mypool.pool.PendingConnections");
      verify(mockMetricRegistry).remove("mypool.pool.MaxConnections");
      verify(mockMetricRegistry).remove("mypool.pool.MinConnections");
   }
}