Measure Code Coverage in a Running Java Application Using JaCoCo

Description

When developing software, it's crucial to know how much of your codebase is covered by tests. This repository demonstrates how to use the JaCoCo (Java Code Coverage) tool to measure code coverage in a running Java application.

Full Article

For a detailed explanation, check out the full article: JaCoCo Code Coverage Guide

Usage

Download JaCoCo Tools

To download the required JaCoCo tools, run the following curl commands:

curl -O https://repo1.maven.org/maven2/org/jacoco/org.jacoco.cli/0.8.12/org.jacoco.cli-0.8.12-nodeps.jar
curl -O https://repo1.maven.org/maven2/org/jacoco/org.jacoco.agent/0.8.12/org.jacoco.agent-0.8.12-runtime.jar

Build the Project

./gradlew build

Run the Java Application with JaCoCo Agent

java '-javaagent:org.jacoco.agent-0.8.12-runtime.jar=port=6300,address=0.0.0.0,destfile=jacoco.exec,includes=com.example.*,append=true,output=tcpserver' -jar build/libs/demo_api_server-0.0.1-SNAPSHOT.jar

Interact with the Application

Example API call:

curl http://localhost:8080/multiple?num1=11&num2=2

Dump Coverage Data

After running your tests or interacting with the application, dump the coverage data:

java -jar org.jacoco.cli-0.8.12-nodeps.jar dump --address localhost --port 6300 --destfile jacoco.exec --reset

Generate HTML Coverage Report

Generate the coverage report to view in the browser:

java -jar org.jacoco.cli-0.8.12-nodeps.jar report jacoco.exec --classfiles build/classes/java/main --sourcefiles src/main/java --html coverage_report

Notes

• Adjust the paths and package names (com.example.*) according to your project structure if they differ.