# LCOV Result Merger

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When you have multiple test suites for the same application you still want to
have the code coverage across all test suites.

This tool will handle this for you.

> See the [Migration Notes](#migrating-notes) below if you are looking to upgrade between major versions.

# Usage

```bash
./node_modules/.bin/lcov-result-merger 'FILE_PATTERN' ['OUTPUT_FILE']
```

# Examples

## Use stdout
1. Generate LCOV Code Coverage into different files, e.g. `build/coverage/coverage_X.log`
2. Run `./node_modules/.bin/lcov-result-merger 'build/coverage/coverage_*.log'`
3. Use the stdout to pipe it to e.g. [Coveralls](http://coveralls.io)
4. Done.

## Use merged output file
1. Generate LCOV Code Coverage into different files, e.g. `build/coverage/coverage_X.log`
2. Run `./node_modules/.bin/lcov-result-merger 'build/coverage/coverage_*.log' 'target/coverage/coverage_merged.log'`
3. Done. Enjoy your merged file.

## Prepend source file paths
Modify source file paths to be relative to the working directory that the merge operation was run in. Useful in
monorepos where each child package gathers its own metrics.

```bash
./node_modules/.bin/lcov-result-merger 'FILE_PATTERN' ['OUTPUT_FILE'] --prepend-source-files
```

Since coverage output is rarely written directly into the project root, use `--prepend-path-fix` to describe the
relative path between the lcov file and the project root. The default simply points to one directory up, "..", which
works well for common tools such as [NYC](https://github.com/istanbuljs/nyc) that write to a `/coverage` directory.

```bash
./node_modules/.bin/lcov-result-merger 'FILE_PATTERN' ['OUTPUT_FILE'] --prepend-source-files --prepend-path-fix "../src"
```

## Migrating Notes
Additional information about breaking changes.

### Version 6
- The `--legacy-temp-file` flag has been removed. This means that if your project is expecting an
  errant `lcov.info` file to be created in the PWD, then it will need to be updated to instead use
  the output file specified when running the command.

- The internal usage of temp files has also been eliminated. This only effects project that are
  directly importing the `mergeCoverageReportFiles` or `mergeCoverageReportFilesStream` functions
  into their own code. Both of these methods now return the merged LCOV content directly, in the
  form of a string, instead of a path to the temporary file where that content could be read.