Local Development¶

Integrate Delta Coverage into your daily development workflow for instant feedback on test coverage.

Basic Workflow¶

Write code
Write tests
Run coverage check
Fix gaps, repeat

./gradlew test deltaCoverage

Recommended Setup¶

Configure for fast local feedback:

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

    reports {
        console.set(true)
        html.set(true)
    }

    reportViews {
        val test by getting {
            violationRules.failIfCoverageLessThan(0.8)
        }
    }
}

Quick Commands¶

Check coverage of current changes¶

./gradlew test deltaCoverage

Compare with different branch¶

./gradlew test deltaCoverage -PdiffBase="refs/remotes/origin/develop"

View HTML report¶

./gradlew test deltaCoverage
open build/reports/coverage-reports/delta-coverage/test/html/index.html

Debug configuration issues¶

./gradlew deltaCoverage -PexplainOnly

IDE Integration¶

IntelliJ IDEA¶

Create a run configuration:

Run → Edit Configurations
Add New → Gradle
Tasks: test deltaCoverage
Name: Delta Coverage

Now run coverage with a single click.

VS Code¶

Add to .vscode/tasks.json:

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "Delta Coverage",
            "type": "shell",
            "command": "./gradlew test deltaCoverage",
            "group": "test"
        }
    ]
}

Git Hooks¶

Run coverage before pushing:

#!/bin/sh
# .git/hooks/pre-push

./gradlew test deltaCoverage || exit 1

Make it executable:

chmod +x .git/hooks/pre-push

Tips¶

Speed Up Feedback¶

Run only unit tests for faster iteration:

./gradlew test deltaCoverageTest

Focus on Specific Module¶

./gradlew :my-module:test deltaCoverageTest

Fetch Remote Before Running¶

If comparing with remote branch, fetch first:

git fetch origin main
./gradlew test deltaCoverage

View Only Changed Classes¶

The HTML report highlights only changed code. Open it to see exactly which lines need tests.

Troubleshooting¶

Empty Report¶

Verify you have uncommitted changes or commits not on main
Run git diff origin/main to see what the plugin will analyze
Use -PexplainOnly to debug

Wrong Files Analyzed¶

Check your diff source configuration
Ensure remote is fetched: git fetch origin
Verify branch name: git branch -a

Tests Pass but Coverage Fails¶

The coverage threshold is too high for your current changes. Either:

Add more tests
Lower the threshold temporarily
Use entityCountThreshold to ignore small changes