Gate Diff Only Test Coverage On Changed Lines Before Merging With Diff Cover

---
name: "Gate Diff Only Test Coverage On Changed Lines Before Merging With Diff Cover"
slug: "gate-diff-only-test-coverage-on-changed-lines-before-merging-with-diff-cover"
description: "Compare coverage reports against a git diff so an agent can flag newly changed lines that still lack tests before merge."
github_stars: 828
verification: "security_reviewed"
source: "https://github.com/Bachmann1234/diff_cover"
author: "Matthias Bachmann and contributors"
publisher_type: "Open Source"
category: "Code Quality & Review"
framework: "Multi-Framework"
tool_ecosystem:
  github_repo: "Bachmann1234/diff_cover"
  github_stars: 828
---

# Gate Diff Only Test Coverage On Changed Lines Before Merging With Diff Cover

Compare coverage reports against a git diff so an agent can flag newly changed lines that still lack tests before merge.

## Prerequisites

Git, supported XML or LCov coverage report, Python 3, pip

## Installation

Use the upstream install or setup path that matches your environment:
- pip install diff-cover
- git clone https://github.com/Bachmann1234/diff-cover.git
- make a pull request from your fork.
- pip install poetry

Requirements and caveats from upstream:
- Currently, diff-cover requires that:
- coverage.py__ (Python)
- poetry manages a python virtual environment and organizes dependencies. It also

Basic usage or getting-started notes:
- ------------
- To install the latest release:
- .. code:: bash

- Source: https://github.com/Bachmann1234/diff_cover
- Extracted from upstream docs: https://raw.githubusercontent.com/Bachmann1234/diff_cover/HEAD/README.rst

## Documentation

- https://github.com/Bachmann1234/diff_cover

## Source

- [Agent Skill Exchange](https://agentskillexchange.com/skills/gate-diff-only-test-coverage-on-changed-lines-before-merging-with-diff-cover/)