Add option to specify sass implementation to use.

CHANGELOG.md

@@ -2,7 +2,15 @@
 
 ## 8.0.0-beta.0 (unreleased)
 
+- FEATURE: Add True `sass` option (`string` or Sass implementation instance,
+  defaults to `'sass'`) to allow using either `sass` or `embedded-sass`.
+- FEATURE: Add the
+  [Node.js package importer](https://sass-lang.com/documentation/js-api/classes/nodepackageimporter/)
+  to the Sass `importers` option by default, if Dart Sass v1.71 or later is
+  available. Users can opt out by providing their own `importers` option, e.g.
+  `{ importers: [] }`.
 - BREAKING: Drop support for node < 18
+- INTERNAL: Remove `sass` as a peer-dependency.
 - INTERNAL: Update dependencies
 
 ## 7.0.1 (01/04/24)

README.md

@@ -35,17 +35,26 @@ Import in your test directory,
 like any other Sass file:
 
 ```scss
-@use 'true' as *;
+@use 'pkg:sass-true' as *;
 ```
 
-Depending on your setup,
-you may need to include the full path name:
+If you are not using the Sass [Node.js package importer][pkg-importer], you may
+need to include the full path name:
 
 ```scss
 // This is only an example, your path may be different
 @use '../node_modules/sass-true' as *;
 ```
 
+Or if you are using the [JavaScript test runner integration][js-runner]:
+
+```scss
+@use 'true' as *;
+```
+
+[pkg-importer]: https://sass-lang.com/documentation/js-api/classes/nodepackageimporter/
+[js-runner]: #using-mocha-jest-or-other-js-test-runners
+
 ## One Setting
 
 `$terminal-output` (boolean),
@@ -146,7 +155,8 @@ when upgrading from an older version of True.
    npm install --save-dev sass-true
    ```
 
-2. [Optional] Install `sass` (Dart Sass), if not already installed.
+2. [Optional] Install Dart Sass (`sass` or `sass-embedded`), if not already
+   installed.
 
    ```bash
    npm install --save-dev sass
@@ -157,7 +167,7 @@ when upgrading from an older version of True.
 4. Write a shim JS test file in `test/sass.test.js`:
 
    ```js
-   const path = require('path');
+   const path = require('node:path');
    const sassTrue = require('sass-true');
 
    const sassFile = path.join(__dirname, 'test.scss');
@@ -185,12 +195,17 @@ You can call `runSass` more than once, if you have multiple Sass test files you
 want to run separately.
 
 The first argument is an object with required `describe` and `it` options, and
-optional `contextLines` and `sourceType` options.
+optional `sass`, `contextLines` and `sourceType` options.
 
 Any JS test runner with equivalents to Mocha's or Jest's `describe` and `it`
 should be usable in the same way: just pass your test runner's `describe` and
 `it` equivalents in the first argument to `runSass`.
 
+The `sass` option is an optional string name of a Dart Sass implementation
+installed in the current environment (e.g. `'embedded-sass'` or `'sass'`), or a
+Dart Sass implementation instance itself. If none is provided, this defaults to
+`'sass'`.
+
 If True can't parse the CSS output, it'll give you some context lines of CSS as
 part of the error message. This context will likely be helpful in understanding
 the parse failure. By default it provides up to 10 lines of context; if you need
@@ -202,14 +217,22 @@ file (passed through to Sass'
 [`compile`](https://sass-lang.com/documentation/js-api/modules#compile)
 function), or a string of source Sass (passed through to Sass'
 [`compileString`](https://sass-lang.com/documentation/js-api/modules#compileString)
-function). By default it is expected to be a path, and `sass.compile` is used --
-to pass in a source string (and use `sass.compileString`), add `sourceType: 'string'` to your options passed in as the first argument to `runSass`.
+function). By default it is expected to be a path, and `sass.compile` is used.
+To pass in a source string (and use `sass.compileString`), add `sourceType:
+'string'` to your options passed in as the first argument to `runSass`.
 
 The third (optional) argument to `runSass` accepts the [same
 options](https://sass-lang.com/documentation/js-api/interfaces/Options) that
-Sass' `compile` or `compileString` expect, and these are passed directly through
-to Sass. The only modification `runSass` makes is to add True's sass path to the
-`loadPaths` option, so `@use 'true';` works in your Sass test file.
+Sass' `compile` or `compileString` expect (e.g. `importers`, `loadPaths`, or
+`style`), and these are passed directly through to Sass.
+
+By default, True makes two modifications to these options. First, True's sass
+path is added to the `loadPaths` option, so `@use 'true';` works in your Sass
+test file. Second, if Dart Sass v1.71 or greater is installed, `importers` is
+set to an array containing the [Node.js package importer][pkg-importer], which
+supports `pkg:` imports to resolve `@use` and `@import` for external modules
+installed via npm or Yarn. If `importers` is set (even as an empty array
+`importers: []`), it will override this default importer.
 
 **Note:** True requires the
 [default Sass `'expanded'` output style](https://sass-lang.com/documentation/js-api/modules#OutputStyle),
@@ -218,15 +241,15 @@ and will not work if `{ style: 'compressed' }` is used in the third argument to
 
 ### Custom Importers
 
-If you use Webpack's tilde notation, like `@use '~accoutrement/sass/tools'`,
-you'll need to tell `runSass` how to handle that. That will require writing a
-[custom importer](https://sass-lang.com/documentation/js-api/interfaces/FileImporter)
+If you use tilde notation (e.g. `@use '~accoutrement/sass/tools'`) or another
+method for importing Sass files from `node_modules`, you'll need to tell
+`runSass` how to handle that. That will require writing a [custom
+importer](https://sass-lang.com/documentation/js-api/interfaces/FileImporter)
 and passing it into the configuration for `runSass`:
 
 ```js
-const path = require('path');
-const { pathToFileURL } = require('url');
-
+const path = require('node:path');
+const { pathToFileURL } = require('node:url');
 const sassTrue = require('sass-true');
 
 const importers = [

package.json

@@ -12,8 +12,6 @@
     "eyeglass-module"
   ],
   "homepage": "https://www.oddbird.net/true/",
-  "main": "./lib/index.js",
-  "types": "./lib/index.d.ts",
   "license": "BSD-3-Clause",
   "repository": {
     "type": "git",
@@ -63,9 +61,6 @@
     "release": "run-s commit docs",
     "prepack": "yarn run release"
   },
-  "peerDependencies": {
-    "sass": ">=1.45.0"
-  },
   "dependencies": {
     "@adobe/css-tools": "^4.3.3",
     "jest-diff": "^29.7.0",
@@ -92,12 +87,20 @@
     "postcss": "^8.4.35",
     "prettier": "^3.2.5",
     "sass": "^1.71.1",
+    "sass-embedded": "^1.71.1",
     "sassdoc": "^2.7.4",
     "sassdoc-theme-herman": "^5.0.1",
     "stylelint": "^16.2.1",
     "stylelint-config-standard-scss": "^13.0.0",
     "typescript": "^5.3.3"
   },
+  "main": "./lib/index.js",
+  "types": "./lib/index.d.ts",
+  "exports": {
+    "types": "./lib/index.d.ts",
+    "sass": "./_index.scss",
+    "default": "./lib/index.js"
+  },
   "eyeglass": {
     "needs": "*",
     "name": "true",

src/index.ts

@@ -1,5 +1,8 @@
-/* eslint-disable @typescript-eslint/no-use-before-define */
 /* eslint-disable no-use-before-define */
+/* eslint-disable @typescript-eslint/no-use-before-define */
+
+import assert from 'node:assert';
+import path from 'node:path';
 
 import {
   CssAtRuleAST,
@@ -9,12 +12,8 @@ import {
   parse as cssParse,
   stringify as cssStringify,
 } from '@adobe/css-tools';
-import * as assert from 'assert';
 import { diffStringsUnified } from 'jest-diff';
 import { find, forEach, last, startsWith } from 'lodash';
-import * as path from 'path';
-import type { Options, StringOptions } from 'sass';
-import { compile, compileString } from 'sass';
 
 import * as constants from './constants';
 import {
@@ -28,6 +27,7 @@ import {
 export interface TrueOptions {
   describe: (description: string, fn: () => void) => void;
   it: (description: string, fn: () => void) => void;
+  sass?: any;
   sourceType?: 'path' | 'string';
   contextLines?: number;
 }
@@ -69,26 +69,62 @@ export type Parser = (rule: Rule, ctx: Context) => Parser;
 export const runSass = function (
   trueOptions: TrueOptions,
   src: string,
-  sassOptions?: Options<'sync'> | StringOptions<'sync'>,
+  sassOptions?: any,
 ) {
   const trueOpts = Object.assign({}, trueOptions);
   const sassOpts = Object.assign({}, sassOptions);
+
+  // Add True's sass to `loadPaths`
   const sassPath = path.join(__dirname, '..', 'sass');
   if (sassOpts.loadPaths) {
     sassOpts.loadPaths.push(sassPath);
   } else {
     sassOpts.loadPaths = [sassPath];
   }
 
-  // Warn if arguments match v6 API
+  // Error if arguments match v6 API
   if (typeof src !== 'string' || !trueOptions.describe || !trueOptions.it) {
     throw new Error(
-      'The arguments provided to `runSass` do not match the new API introduced in True v7. Refer to the v7 release notes for migration documentation: https://github.com/oddbird/true/releases/tag/v7.0.0',
+      'The arguments provided to `runSass` do not match the new API ' +
+        'introduced in True v7. Refer to the v7 release notes ' +
+        'for migration documentation: ' +
+        'https://github.com/oddbird/true/releases/tag/v7.0.0',
+    );
+  }
+
+  // Error if `style: "compressed"` is used
+  if (sassOpts.style === 'compressed') {
+    throw new Error(
+      'True requires the default Sass `expanded` output style, ' +
+        'but `style: "compressed"` was used.',
     );
   }
 
-  const compiler = trueOpts.sourceType === 'string' ? compileString : compile;
-  const parsedCss = compiler(src, sassOpts).css;
+  let compiler;
+  if (trueOpts.sass && typeof trueOpts.sass !== 'string') {
+    compiler = trueOpts.sass;
+  } else {
+    const sassPkg = trueOpts.sass ?? 'sass';
+    try {
+      // eslint-disable-next-line global-require
+      compiler = require(sassPkg);
+    } catch (err) {
+      throw new Error(`Cannot find Dart Sass (\`${sassPkg}\`) dependency.`);
+    }
+  }
+
+  // Add the Sass Node.js package importer, if available
+  if (!sassOpts.importers) {
+    try {
+      sassOpts.importers = [new compiler.NodePackageImporter()];
+    } catch (err) {
+      // skip if `NodePackageImporter` isn't available
+    }
+  }
+
+  const compilerFn =
+    trueOpts.sourceType === 'string' ? 'compileString' : 'compile';
+  const parsedCss = compiler[compilerFn](src, sassOpts).css;
   const modules = parse(parsedCss, trueOpts.contextLines);
 
   forEach(modules, (module) => {