Coverage report is not only generated for changed files in watch mode

[netcoding87]

Describe the bug

As a developer using Vitest I want to coverage report in watch mode only for files affected by code changes instead of all so that I can easily see how my changes affected the code.

I know this behavior from using jest on projects setup with cra. In my current project with more than 100 files it is very frustrating to have to search out the files from the report after every run...

Reproduction

Repository to investigate: https://github.com/netcoding87/vitest-coverage (see README.md)

System Info

System:
    OS: macOS 12.6.1
    CPU: (8) arm64 Apple M1 Pro
    Memory: 246.67 MB / 16.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 16.13.2 - ~/.nvm/versions/node/v16.13.2/bin/node
    npm: 8.1.2 - ~/.nvm/versions/node/v16.13.2/bin/npm
  Browsers:
    Chrome: 107.0.5304.110
    Firefox: 106.0.3
    Safari: 16.1
  npmPackages:
    @vitejs/plugin-react: ^2.2.0 => 2.2.0 
    vite: ^3.2.3 => 3.2.3 
    vitest: ^0.25.1 => 0.25.1

Used Package Manager

npm

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• Read the Contributing Guidelines.
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• The provided reproduction is a minimal reproducible example of the bug.

[DevathiMahesh]

Yes. Even i am facing the same issue. Its running for all the files in the codebase.......

[AriPerkkio]

@netcoding87, @DevathiMahesh, does cleanOnRerun work for you? In the reproduction case it is providing same experience as Jest does. It doesn't exactly limit the included files to only those ones that have changed, but includes those ones that are used by the test that was re-run. This will limit the coverage report a lot.

import { defineConfig } from "vitest/config";

export default defineConfig({
  test: {
    coverage: {
      provider: "istanbul",
      cleanOnRerun: true,
    },
    reporters: "verbose",
  },
});

What Jest does is more complicated. It's using git to see which files have changes, and includes only those ones in coverage report.

• https://jestjs.io/docs/jest-platform#jest-changed-files
• https://archive.jestjs.io/blog/2018/05/29/jest-23-blazing-fast-delightful-testing#other-improvements