alternate-file

In Vim, you can often go to the "alternate file" for the active buffer - usually the spec file for an implementation, or vice versa - by pressing :A. This extension adds exposes core functionality to build that behaviour into other editors, and also includes a CLI tool for broader integration.

alternate-file reads a config file based on the .projections.json file from Tim Pope's Projectionist. This lets you specify where the spec files for different types of files in your project are set up. One you have a .projections.json in your file tree, you can use this library to find or create a spec for an implementation file, or vice versa.

.projections.json

To describe your project's layout, create a .projections.json in the root of your project.

Each line should have the pattern for an implementation file as the key, and an object with the pattern for the alternate file (usually the spec file, but it can be whatever you want). Use a * in the main pattern and a {} in the alternate pattern to note the part of the path that should be the same between the two files. A * can stand in for an arbitrarily deep path.

Split paths

If your test paths have an extra directly in the middle of them, like with app/some/path/__test__/file.test.js with Jest, you can use {dirname} for the directory path and {basename} for the filename. You can do the same thing on the implementation side with the standard glob syntax: ** to represent the directory path, and * to represent the filename, like app/**/something/*.js.

If your paths have more than two variable parts, that can work too! You can use multiple sets of **/{dirname} pairs, which allows you to do something like:

"apps/**/lib/**/*.ex": {
  "alternate": "apps/{dirname}/test/{dirname}/{basename}_test.exs"
}

Multiple alternates

If your project is inconsistent about where specs go (it happens to the best of us), you can also pass an array to alternate. The extension will look for a file matching the first alternate, then the second, and so on. When you create an alternate file, it will always follow the first pattern.

Note that this isn't part of the original projectionist spec, but it's sometimes handy.

Examples

{
  // Basic
  // app/foo/bar/file.js => app/foo/bar/file.spec.js
  "app/*.js": { "alternate": "app/{}.spec.js" },
  // Dirname/Basename
  // app/foo/bar/file.js => app/foo/bar/__test__/file.test.js
  "*.js": { "alternate": "{dirname}/__test__/{basename}.test.js" },
  // Globbed implementation:
  // app/foo/bar/js/file.js => test/foo/bar/file_test.js
  "app/**/js/*.js": { "alternate": "test/{}/_test.js" },
  // Multiple alternatives
  // app/foo/bar/file.jsx =>
  //   app/foo/bar/file.spec.jsx OR app/foo/bar/file.spec.js OR
  //   spec/js/foo/bar/file_spec.js
  "app/*.jsx": { "alternate": ["app/{}.spec.jsx", "app/{}.spec.js", "spec/js/{}_spec.js"] }
}

For .projections.json files for popular frameworks, see the sample-projections. If your framework isn't in there, PRs for new sample-projections are welcome!

Contributing

Setup

Clone the repository, then

yarn install

Run Unit Tests

yarn test

Roadmap

• Support templates for auto-populating new files.
• Automatically create default .projection.json files
• Support all the transformations from Projectionist, not just dirname and basename.
• Support the "type" attribute in .projections.json, and allow for lookup by filetype, like for "controller/view/template".