JaCoCo Console Reporter Maven Plugin

A smart Maven plugin that generates textual tree-like coverage reports from JaCoCo execution data with intelligent auto-detection of project configurations. Displays coverage metrics (Class %, Method %, Branch %, Line %) for packages, source files, and the entire project with minimal configuration required.

Key Features

Intelligent Auto-Detection

• JaCoCo Plugin Integration: Automatically detects and applies exclusion patterns from your existing JaCoCo plugin configuration
• Sonar Pattern Support: Reads and interprets sonar.exclusions and sonar.coverage.exclusions from project properties
• Build Directory Exclusion: Automatically excludes auto-generated files by parsing package declarations in the build directory
• Multi-Module Support: Aggregates coverage data across all modules when used in multi-module builds
• Charset Detection: Automatically detects console encoding (UTF-8 vs ASCII) for proper tree character rendering

Smart Defaults

• Deferred Reporting: Waits until the last module in multi-module builds to provide aggregated coverage
• Execution Data Deduplication: Prevents double-counting of coverage when aggregating multiple modules
• Zero Configuration: Works out-of-the-box with standard Maven/JaCoCo setups

Flexible Output Options

• Tree-like package structure visualization with collapsible paths
• Individual source file metrics (optional)
• Combined weighted coverage score with customizable weights
• Optional aggregated JaCoCo XML report generation
• Console-optimized formatting with proper Unicode/ASCII fallback

Prerequisites

• Maven 3.x
• JaCoCo plugin configured in your project (the console reporter will auto-detect its configuration)

Installation

Add the plugin to your project's pom.xml:

<build>
    <plugins>
        <plugin>
            <groupId>io.github.svaningelgem</groupId>
            <artifactId>jacoco-console-reporter</artifactId>
            <version>1.0.0</version>
            <executions>
                <execution>
                    <goals>
                        <goal>report</goal>
                    </goals>
                    <phase>verify</phase>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Usage

Run the plugin after tests:

mvn verify

The plugin automatically detects your JaCoCo configuration and generates a console report with no additional setup required.

How Auto-Detection Works

JaCoCo Plugin Integration

The plugin automatically scans your project's JaCoCo plugin configuration to extract:

• Exclusion patterns from <excludes><exclude> elements
• Custom exec file locations from <destFile> configurations
• Multiple execution configurations across different plugin executions

Sonar Integration

Reads exclusion patterns from project properties:

<properties>
    <sonar.exclusions>src/main/java/com/example/generated/**,**/*Generated.java</sonar.exclusions>
    <sonar.coverage.exclusions>src/test/java/**,**/*Test.java</sonar.coverage.exclusions>
</properties>

Build Directory Analysis

Automatically excludes generated files by:

1. Scanning the target directory for .java files
2. Parsing package declarations to determine class names
3. Creating exclusion patterns for the corresponding .class files

This prevents artificially low coverage scores caused by generated code.

Configuration Options

While the plugin works with zero configuration, you can customize its behavior:

Parameter	Description	Default Value
deferReporting	Wait until last module in multi-module builds	true
showFiles	Display individual source files in tree	false
showMissingLines	Display uncovered line numbers for each file (requires showFiles=true)	false
showTree	Display hierarchical package tree	true
showSummary	Display overall coverage summary	true
ignoreFilesInBuildDirectory	Auto-exclude generated files	true
interpretSonarIgnorePatterns	Apply Sonar exclusion patterns	true
writeXmlReport	Enable XML report generation	false
xmlOutputFile	Path for the generated XML report	${session.executionRootDirectory}/coverage.xml

Coverage Weight Customization

Control how the combined coverage score is calculated:

Parameter	Description	Default
weightClassCoverage	Weight for class coverage	0.1
weightMethodCoverage	Weight for method coverage	0.1
weightBranchCoverage	Weight for branch coverage	0.4
weightLineCoverage	Weight for line coverage	0.4

Sample Output

Default Tree View

[INFO] Overall Coverage Summary
[INFO] Package                                    │ Class, %         │ Method, %        │ Branch, %        │ Line, %
[INFO] ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
[INFO] com.example                                │ 100.00% (3/3)    │ 83.33% (5/6)     │ 50.00% (2/4)     │ 75.00% (15/20)
[INFO] ├─model                                    │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)
[INFO] └─util                                     │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)
[INFO] ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
[INFO] all classes                                │ 100.00% (3/3)    │ 83.33% (5/6)     │ 50.00% (2/4)     │ 75.00% (15/20)

With File Details (showFiles=true)

[INFO] com.example                                │ 100.00% (3/3)    │ 83.33% (5/6)     │ 50.00% (2/4)     │ 75.00% (15/20)
[INFO] ├─model                                    │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)
[INFO] │ └─Model.java                             │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)
[INFO] ├─util                                     │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)
[INFO] │ └─Util.java                              │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)
[INFO] └─Example.java                             │ 100.00% (1/1)    │ 33.33% (1/2)     │ 0.00% (0/0)      │ 25.00% (1/4)

With Missing Lines (showFiles=true and showMissingLines=true)

[INFO] com.example                                │ 100.00% (3/3)    │ 83.33% (5/6)     │ 50.00% (2/4)     │ 75.00% (15/20)
[INFO] ├─model                                    │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)
[INFO] │ └─Model.java                             │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)   Missing: 45
[INFO] ├─util                                     │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)
[INFO] │ └─Util.java                              │ 100.00% (1/1)    │ 100.00% (2/2)    │ 50.00% (1/2)     │ 87.50% (7/8)   Missing: 23
[INFO] └─Example.java                             │ 100.00% (1/1)    │ 33.33% (1/2)     │ 0.00% (0/0)      │ 25.00% (1/4)   Missing: 33-35, 39

The missing lines are displayed in a compact format:

• Individual uncovered lines: 23, 45, 67
• Ranges of consecutive uncovered lines: 33-35
• Combination: 23, 33-35, 39, 45-48
• Partially covered lines are shown with "partial: " prefix

Summary Section

[INFO] Overall Coverage Summary
[INFO] ------------------------
[INFO] Class coverage : 100.00% (3/3)
[INFO] Method coverage: 83.33% (5/6)
[INFO] Branch coverage: 50.00% (2/4)
[INFO] Line coverage  : 75.00% (15/20)
[INFO] Combined coverage: 68.33% (Class 10%, Method 10%, Branch 40%, Line 40%)

Advanced Configuration Examples

Multi-Module with Custom Weights and XML Output

<plugin>
    <groupId>io.github.svaningelgem</groupId>
    <artifactId>jacoco-console-reporter</artifactId>
    <version>1.0.0</version>
    <configuration>
        <!-- Enable XML report generation -->
        <writeXmlReport>true</writeXmlReport>
        <xmlOutputFile>${project.build.directory}/aggregated-coverage.xml</xmlOutputFile>
        <!-- Emphasize line and branch coverage over class/method -->
        <weightClassCoverage>0.05</weightClassCoverage>
        <weightMethodCoverage>0.15</weightMethodCoverage>
        <weightBranchCoverage>0.4</weightBranchCoverage>
        <weightLineCoverage>0.4</weightLineCoverage>
    </configuration>
</plugin>

Detailed File-Level Reporting

<plugin>
    <groupId>io.github.svaningelgem</groupId>
    <artifactId>jacoco-console-reporter</artifactId>
    <version>1.0.0</version>
    <configuration>
        <showFiles>true</showFiles>
        <showMissingLines>true</showMissingLines>
        <writeXmlReport>true</writeXmlReport>
    </configuration>
</plugin>

Disable Auto-Detection Features

<plugin>
    <groupId>io.github.svaningelgem</groupId>
    <artifactId>jacoco-console-reporter</artifactId>
    <version>1.0.0</version>
    <configuration>
        <!-- Disable automatic exclusions if you want full control -->
        <ignoreFilesInBuildDirectory>false</ignoreFilesInBuildDirectory>
        <interpretSonarIgnorePatterns>false</interpretSonarIgnorePatterns>
    </configuration>
</plugin>

Immediate Reporting per Module

<plugin>
    <groupId>io.github.svaningelgem</groupId>
    <artifactId>jacoco-console-reporter</artifactId>
    <version>1.0.0</version>
    <configuration>
        <!-- Report immediately for each module instead of waiting -->
        <deferReporting>false</deferReporting>
    </configuration>
</plugin>

Integration with Existing Tools

JaCoCo Plugin Compatibility

The console reporter automatically respects your existing JaCoCo configuration:

<!-- Your existing JaCoCo setup -->
<plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <configuration>
        <excludes>
            <exclude>com/example/generated/**/*</exclude>
            <exclude>**/*DTO.class</exclude>
        </excludes>
        <destFile>${project.build.directory}/custom-jacoco.exec</destFile>
    </configuration>
</plugin>

        <!-- Console reporter automatically detects the above configuration -->
<plugin>
<groupId>io.github.svaningelgem</groupId>
<artifactId>jacoco-console-reporter</artifactId>
<version>1.0.0</version>
<!-- No additional configuration needed -->
</plugin>

Sonar Integration

Works seamlessly with existing Sonar configurations:

<properties>
    <!-- Console reporter automatically applies these patterns -->
    <sonar.exclusions>
        src/main/java/com/example/generated/**,
        **/*Generated.java,
        **/target/**
    </sonar.exclusions>
    <sonar.coverage.exclusions>
        src/test/java/**,
        **/*Test.java
    </sonar.coverage.exclusions>
</properties>

Multi-Module Builds

In multi-module projects, the plugin:

1. Collects execution data from each module's JaCoCo configuration
2. Aggregates all coverage data across modules
3. By default, defers reporting until the last module (controlled by deferReporting)
4. Deduplicates coverage data to prevent double-counting shared code

Example multi-module configuration:

<!-- In parent pom.xml -->
<build>
    <pluginManagement>
        <plugins>
            <plugin>
                <groupId>io.github.svaningelgem</groupId>
                <artifactId>jacoco-console-reporter</artifactId>
                <version>1.0.0</version>
                <configuration>
                    <deferReporting>true</deferReporting>
                    <writeXmlReport>true</writeXmlReport>
                </configuration>
            </plugin>
        </plugins>
    </pluginManagement>
</build>

        <!-- In each module's pom.xml -->
<build>
<plugins>
    <plugin>
        <groupId>io.github.svaningelgem</groupId>
        <artifactId>jacoco-console-reporter</artifactId>
    </plugin>
</plugins>
</build>

Technical Implementation

Execution Data Merging

The plugin uses intelligent deduplication when processing multiple exec files:

• Tracks unique class IDs to prevent double-counting
• Merges execution data at the line level using JaCoCo's built-in merging
• Handles overlapping coverage from shared dependencies

Pattern Matching

Supports both JaCoCo-style and Sonar-style exclusion patterns:

• JaCoCo patterns: com/example/**/*.class, **/*Controller.class
• Sonar patterns: src/main/java/**, **/*Test.java

Console Rendering

Automatically detects terminal capabilities:

• Uses Unicode box-drawing characters (├─└─│) for UTF-8 terminals
• Falls back to ASCII characters (+-|) for legacy terminals
• Handles Windows console code page detection via JNA

Contributing

The plugin is designed to work with minimal configuration while providing extensive customization options for advanced use cases. Contributions are welcome!

Building from Source

mvn clean install

Running Tests

mvn test