Custom less filemanager (#1289)

Author: Jasper De Moor

src/assets/LESSAsset.js

@@ -1,6 +1,10 @@
 const Asset = require('../Asset');
 const localRequire = require('../utils/localRequire');
 const promisify = require('../utils/promisify');
+const Resolver = require('../Resolver');
+const syncPromise = require('../utils/syncPromise');
+const fs = require('../utils/fs');
+const path = require('path');
 
 class LESSAsset extends Asset {
   constructor(name, options) {
@@ -54,8 +58,39 @@ function urlPlugin(asset) {
 
       visitor.run = visitor.visit;
       pluginManager.addVisitor(visitor);
+
+      let LessFileManager = getFileManager(less, asset.options);
+      pluginManager.addFileManager(new LessFileManager());
     }
   };
 }
 
+function getFileManager(less, options) {
+  const resolver = new Resolver({
+    extensions: ['.css', '.less'],
+    rootDir: options.rootDir
+  });
+
+  class LessFileManager extends less.FileManager {
+    async resolve(filename, currentDirectory) {
+      return (await resolver.resolve(
+        filename,
+        path.join(currentDirectory, 'index')
+      )).path;
+    }
+
+    async loadFile(filename, currentDirectory) {
+      filename = await this.resolve(filename, currentDirectory);
+      let contents = await fs.readFile(filename, 'utf8');
+      return {contents, filename};
+    }
+
+    loadFileSync(filename, currentDirectory) {
+      return syncPromise(this.loadFile(filename, currentDirectory));
+    }
+  }
+
+  return LessFileManager;
+}
+
 module.exports = LESSAsset;

test/integration/less-advanced-import/base.less

@@ -0,0 +1,5 @@
+@base: #f938ab;
+
+.base {
+  color: @base;
+}

test/integration/less-advanced-import/index.js

@@ -0,0 +1,5 @@
+require('~/index.less');
+
+module.exports = function () {
+  return 2;
+};

test/integration/less-advanced-import/index.less

@@ -0,0 +1,5 @@
+@import '~/base.less';
+
+.index {
+  color: @base;
+}

test/less.js

@@ -56,6 +56,35 @@ describe('less', function() {
     assert(css.includes('.base'));
   });
 
+  it('should support advanced less imports', async function() {
+    let b = await bundle(
+      __dirname + '/integration/less-advanced-import/index.js'
+    );
+
+    assertBundleTree(b, {
+      name: 'index.js',
+      assets: ['index.js', 'index.less'],
+      childBundles: [
+        {
+          type: 'map'
+        },
+        {
+          name: 'index.css',
+          assets: ['index.less'],
+          childBundles: []
+        }
+      ]
+    });
+
+    let output = run(b);
+    assert.equal(typeof output, 'function');
+    assert.equal(output(), 2);
+
+    let css = fs.readFileSync(__dirname + '/dist/index.css', 'utf8');
+    assert(css.includes('.index'));
+    assert(css.includes('.base'));
+  });
+
   it('should support requiring empty less files', async function() {
     let b = await bundle(__dirname + '/integration/less-empty/index.js');