nanovision

The code coverage visualization tool that understands your code

Here is an example report, its a self coverage report of the nanovision project.

For more details check the docs

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nanovision converts coverage reports (Cobertura, GoCover, GCov) into human-readable visualizations.

View Example Report   |   Read the Docs

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Why nanovision?

While many CI tools give you a simple percentage, nanovision helps you understand what is covered and why it matters.

• High Performance: Written in Go. Fast parsing, low memory footprint.
• Report Merging: Combine Unit, Integration reports into a single unified view.
• Patch Coverage: Analyze coverage specifically on new code (using diffs) to stop technical debt before it merges.
• Deep Analysis: Calculates cyclomatic complexity and method/functions level metrics.
• Modern UI: Generates a static, html pages that are easy to host anywhere.

Supported Formats

Input Formats	Output Formats
Cobertura	HTML
Go Cover	Text Summary
GCov	LCOV
	Raw JSON

Installation

Windows

winget install nanovision

Linux

curl -sL https://raw.githubusercontent.com/IgorBayerl/nanovision/main/scripts/install.sh | bash

Or downdload From Releases

Download the binaries for Windows or Linux from the Releases Page.

Quick Start

0. Check nanovision instalation

nanovision -version

nanovision -help

1. Generate a basic HTML report

nanovision -report="coverage.out" -sourcedirs="."

2. Merge multiple reports

Combine coverage from different languages or test suites:

nanovision -report="cobertura.xml;gocover.out" -sourcedirs="src/csharp;src/go"

3. Patch Coverage (Diff Analysis)

Focus only on the lines changed in your branch (great for PR checks):

# 1. Generate a diff file
git diff main > changes.diff

# 2. Run nanovision with the diff flag
nanovision -report="coverage.out" -sourcedirs="." -diff="changes.diff"

Configuration

You can run nanovision entirely via CLI flags, or use a nanovision.yaml file for complex setups (like file filtering, risk thresholds, and excluded paths).

See the Configuration Documentation for details.

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for details on setting up the dev environment (Devcontainer included).

License

Licensed under the Apache 2.0 License.

Credits

• Inspired by the excellent ReportGenerator by Daniel Palme.

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