Does Karma resolve a relative basePath against the config file or the CI working directory?

Question

One config file, two effective rootsA shared karma.conf.js is expected to drive both local watch runs and CI single runs; assume Karma 6.x. Karma's documented rule is that a relative basePath resolves against the location of the configuration file itself. Pipelines that generate the config into a temporary directory, wrap it in a build tool, or launch the runner from another working directory can still shift the effective root, changing which entries the files, exclude, and preprocessors patterns pick up.Two constraints complicate a one-line fix. Watch mode and singleRun manage the served file set differently, so a resolution divergence may surface in only one mode. A Karma 7 upgrade may also require coverage reporter configuration changes, raising the stakes of pinning this behavior now.Three points would settle the design:Is relative basePath resolution strictly anchored to the config file's directory, regardless of the invoking working directory?Do watch and single-run modes resolve the initial file list through the same path, so a root mismatch must appear in both?Would anchoring basePath with __dirname remove the ambiguity without altering served URLs that urlRoot or proxies rely on?

Tasadduq Burney · Answer

Answer
Karma treats a relative basePath as relative to the directory that contains the karma.conf.js file, not to the process' current working directory (the CI workspace or local shell).
Confirmed facts

The basePath is computed once when the configuration is loaded (Karma 6.x and 7.x).
Because the calculation happens at load time, both watch mode and singleRun use the same effective basePath.
Using __dirname (or path.resolve(__dirname, …)) explicitly anchors the path to the config file’s directory.

Verification steps

Create a layout: project/
  karma.conf.js
  src/
    test.js
In karma.conf.js set basePath: 'src'.
From the project root run karma start --single-run and confirm test.js is served.
Change to a temporary directory (e.g., cd /tmp) and invoke Karma with an explicit config: karma start --single-run --config /full/path/to/project/karma.conf.js. The same test.js should still be served, proving basePath follows the config file location.
Optionally add console.log('basePath dir:', __dirname) inside the config to see the directory used.

Does Karma resolve a relative basePath against the config file or the CI working directory?

One config file, two effective roots

1 answer

Answer

Confirmed facts

Verification steps

Your perspective belongs here.

0 question comments