Delta Coverage¶

Code coverage for what matters — your changes

Delta Coverage is a tool that computes code coverage of new/modified code based on a git diff. Focus on testing what you've changed, not the entire codebase. Available as a Gradle plugin or a standalone CLI tool.

Get Started View on GitHub

Why Delta Coverage?¶

⚡ Instant Feedback: Get coverage reports for your changes in seconds. No waiting for SonarQube scans or external service delays.
🧪 Testing Pyramid Support: Separate views for unit tests, integration tests, and E2E tests. Enforce different coverage thresholds per test type.
🆓 Free, No Infrastructure: Runs locally and in CI. No servers to maintain, no licenses to pay, no external dependencies.

Quick Start¶

Kotlin DSLGroovy DSLCLI

1. Apply the plugin

plugins {
    id("io.github.gw-kit.delta-coverage") version "3.6.0"
}

2. Configure diff source

configure<io.github.surpsg.deltacoverage.gradle.DeltaCoverageConfiguration> {
    diffSource.git.compareWith("refs/remotes/origin/main")
}

3. Run coverage

./gradlew test deltaCoverage

1. Apply the plugin

plugins {
    id 'io.github.gw-kit.delta-coverage' version '3.6.0'
}

2. Configure diff source

deltaCoverageReport {
    diffSource.git.compareWith('refs/remotes/origin/main')
}

3. Run coverage

./gradlew test deltaCoverage

1. Download the CLI

curl -L -o delta-coverage-cli.jar \
  https://repo1.maven.org/maven2/io/github/gw-kit/delta-coverage-cli/3.6.0/delta-coverage-cli-3.6.0.jar

2. Generate a diff

git diff origin/main...HEAD > changes.diff

3. Run coverage

java -jar delta-coverage-cli.jar \
  --engine JACOCO \
  --diff-file changes.diff \
  --coverage-binary build/jacoco/test.exec \
  --classes build/classes/java/main \
  --sources src/main/java \
  --html --console

That's it! The plugin auto-discovers your test tasks, generates HTML reports, and enforces coverage on new code.

Full Quick Start Guide

Features¶

Two Coverage Engines — Choose between JaCoCo (standard JVM) or IntelliJ coverage (better for Kotlin)
Multiple Report Formats — HTML, XML, Markdown, and Console reports
Automatic Test Discovery — Report views are auto-created for all test tasks
Flexible Diff Sources — Use file, URL, or git to provide the diff
GitHub Actions Integration — Post coverage reports directly to PR comments
CLI Tool — Run delta coverage without Gradle plugin

How It Works¶

Delta Coverage takes your test coverage data and filters it to show only the lines you've changed. This gives you actionable feedback on your work, not noise from legacy code.

Delta Coverage HTML Report

What Users Say¶

"Delta Coverage made our code reviews faster. We stopped arguing about which code needs tests — the report shows it clearly."

"Onboarding new developers is easier. They can focus on testing their changes without worrying about overall project coverage."

Get Started¶

Ready to try Delta Coverage? The Quick Start guide will have you running in under 5 minutes.

For a comparison with other tools, see Delta Coverage vs SonarQube.