# Oxc Resolver

* [enhanced-resolve](https://github.com/webpack/enhanced-resolve) configurations
* built-in [tsconfig-paths-webpack-plugin](https://github.com/dividab/tsconfig-paths-webpack-plugin)
  * support extending tsconfig defined in `tsconfig.extends`
  * support paths alias defined in `tsconfig.compilerOptions.paths`
  * support project references defined `tsconfig.references`
* contains `tracing` instrumentation
  * Install `tracing_subscriber` in your app
  * or opt-in to the subscriber with `--features tracing-subscriber` and use `OXC_RESOLVER=DEBUG` env variable

#### Resolver Options

| Done | Field            | Default                     | Description                                                                                                                                               |
|------|------------------|-----------------------------| --------------------------------------------------------------------------------------------------------------------------------------------------------- |
|  ✅  | alias            | []                          | A list of module alias configurations or an object which maps key to value                                                                                |
|  ✅  | aliasFields      | []                          | A list of alias fields in description files                                                                                                               |
|  ✅  | extensionAlias   | {}                          | An object which maps extension to extension aliases                                                                                                       |
|      | cachePredicate   | function() { return true }; | A function which decides whether a request should be cached or not. An object is passed to the function with `path` and `request` properties.             |
|      | cacheWithContext | true                        | If unsafe cache is enabled, includes `request.context` in the cache key                                                                                   |
|  ✅  | conditionNames   | []                          | A list of exports field condition names                                                                                                                   |
|  ✅  | descriptionFiles | ["package.json"]            | A list of description files to read from                                                                                                                  |
|  ✅  | enforceExtension | false                       | Enforce that a extension from extensions must be used                                                                                                     |
|  ✅  | exportsFields    | ["exports"]                 | A list of exports fields in description files                                                                                                             |
|  ✅  | extensions       | [".js", ".json", ".node"]   | A list of extensions which should be tried for files                                                                                                      |
|  ✅  | fallback         | []                          | Same as `alias`, but only used if default resolving fails                                                                                                 |
|  ✅  | fileSystem       |                             | The file system which should be used                                                                                                                      |
|  ✅  | fullySpecified   | false                       | Request passed to resolve is already fully specified and extensions or main files are not resolved for it (they are still resolved for internal requests) |
|  ✅  | mainFields       | ["main"]                    | A list of main fields in description files                                                                                                                |
|  ✅  | mainFiles        | ["index"]                   | A list of main files in directories                                                                                                                       |
|  ✅  | modules          | ["node_modules"]            | A list of directories to resolve modules from, can be absolute path or folder name                                                                        |
|      | plugins          | []                          | A list of additional resolve plugins which should be applied                                                                                              |
|      | resolver         | undefined                   | A prepared Resolver to which the plugins are attached                                                                                                     |
|  ✅  | resolveToContext | false                       | Resolve to a context instead of a file                                                                                                                    |
|  ✅  | preferRelative   | false                       | Prefer to resolve module requests as relative request and fallback to resolving as module                                                                 |
|  ✅  | preferAbsolute   | false                       | Prefer to resolve server-relative urls as absolute paths before falling back to resolve in roots                                                          |
|  ✅  | restrictions     | []                          | A list of resolve restrictions                                                                                                                            |
|  ✅  | roots            | []                          | A list of root paths                                                                                                                                      |
|  ✅  | symlinks         | true                        | Whether to resolve symlinks to their symlinked location                                                                                                   |
|      | unsafeCache      | false                       | Use this cache object to unsafely cache the successful requests

## Test

Tests ported from
* [enhanced-resolve](https://github.com/webpack/enhanced-resolve/tree/main/test)
* [tsconfig-path](https://github.com/dividab/tsconfig-paths/blob/master/src/__tests__/data/match-path-data.ts) and [parcel-resolver](https://github.com/parcel-bundler/parcel/tree/v2/packages/utils/node-resolver-core/test/fixture/tsconfig) for tsconfig-paths

Test cases are located in `./src/tests`, fixtures are located in `./tests`

Crossed out test files are irrelevant.

- [x] ~CachedInputFileSystem.test.js~
- [x] ~SyncAsyncFileSystemDecorator.test.js~
- [x] alias.test.js
- [x] browserField.test.js
- [ ] dependencies.test.js
- [x] exportsField.test.js
- [x] extension-alias.test.js
- [x] extensions.test.js
- [x] fallback.test.js
- [x] ~forEachBail.test.js~
- [x] fullSpecified.test.js
- [x] ~getPaths.test.js~
- [x] identifier.test.js (see unit test in `crates/oxc_resolver/src/request.rs`)
- [x] importsField.test.js
- [x] incorrect-description-file.test.js (need to add ctx.fileDependencies)
- [ ] missing.test.js
- [x] path.test.js (see unit test in `crates/oxc_resolver/src/path.rs`)
- [ ] plugins.test.js
- [ ] pnp.test.js
- [x] ~pr-53.test.js~
- [x] resolve.test.js
- [x] restrictions.test.js (partially done, regex is not supported yet)
- [x] roots.test.js
- [x] scoped-packages.test.js
- [x] simple.test.js
- [x] symlink.test.js
- [x] ~unsafe-cache.test.js~
- [x] ~yield.test.js~