Merge pull request #893 from DanPurdy/feature/strip-bom

Fix BOM markers causing parse issues

lib/groot.js

@@ -3,14 +3,15 @@
 //////////////////////////////
 'use strict';
 
-var gonzales = require('gonzales-pe'),
-    fm = require('front-matter');
+var gonzales = require('gonzales-pe');
+var fm = require('front-matter');
+var helpers = require('./helpers');
 
 module.exports = function (text, syntax, filename) {
   var tree;
 
   // Run `.toString()` to allow Buffers to be passed in
-  text = text.toString();
+  text = helpers.stripBom(text.toString());
 
   // if we're skipping front matter do it here, fall back to just our text in case it fails
   if (fm.test(text)) {

lib/helpers.js

@@ -394,4 +394,24 @@ helpers.isPartialStringMatch = function (needle, haystack) {
   return false;
 };
 
+/**
+ *  A copy of the the stripBom module from https://github.com/sindresorhus/strip-bom/blob/master/index.js
+ *  The module requires node > 4 whereas we support earlier versions.
+ *  This function strips the BOM marker from the beginning of a file
+ *
+ * @param {string} str - The string we wish to strip the BOM marker from
+ * @returns {string} The string without a BOM marker
+ */
+helpers.stripBom = function (str) {
+  if (typeof str !== 'string') {
+    throw new TypeError('Expected a string, got ' + typeof str);
+  }
+
+  if (str.charCodeAt(0) === 0xFEFF) {
+    return str.slice(1);
+  }
+
+  return str;
+};
+
 module.exports = helpers;

tests/bom-utf8/starts-with-mixin-utf8-bom.scss

@@ -0,0 +1,5 @@
+@mixin foo(
+  $param: 'def'
+) {
+  color: red;
+}

tests/bom-utf8/var-utf8-bom.scss

@@ -0,0 +1,5 @@
+$my-color: red;
+
+body {
+  color: $my-color;
+}

tests/cli.js

@@ -472,3 +472,43 @@ describe('cli', function () {
     });
   });
 });
+
+// ==============================================================================
+//  UTF-8 BOM
+// ==============================================================================
+
+describe('Reading files with UTF-8 BOM', function () {
+  before(function () {
+    var testText = fs.readFileSync('tests/bom-utf8/starts-with-mixin-utf8-bom.scss').toString();
+    if (testText.charCodeAt(0) !== 0xFEFF) {
+      throw new Error('BOM test files have no BOM markers');
+    }
+  });
+
+  it('should not throw a parse error from file containing a BOM', function (done) {
+    var command = 'node bin/sass-lint -v tests/bom-utf8/starts-with-mixin-utf8-bom.scss --format json';
+
+    exec(command, function (err, stdout) { // eslint-disable-line handle-callback-err
+      var result = JSON.parse(stdout)[0];
+
+      // Files with BOM markers that start with a mixin throw a fatal error
+      // https://github.com/sasstools/sass-lint/issues/880
+      assert.equal(result.errorCount, 0);
+      done();
+    });
+  });
+
+  it('should return the correct amount of warnings from a file containing BOM markers', function (done) {
+    var command = 'node bin/sass-lint -v tests/bom-utf8/var-utf8-bom.scss --format json';
+
+    exec(command, function (err, stdout) { // eslint-disable-line handle-callback-err
+      var result = JSON.parse(stdout)[0];
+
+      // Files starting with variables threw extra errors
+      // see https://github.com/sasstools/sass-lint/issues/880
+      assert.equal(result.errorCount, 0);
+      assert.equal(result.warningCount, 2);
+      done();
+    });
+  });
+});

tests/helpers/stripBom.js

@@ -0,0 +1,28 @@
+'use strict';
+
+var assert = require('assert'),
+    helpers = require('../../lib/helpers'),
+    fs = require('fs');
+
+describe('helpers - stripBom', function () {
+
+  //////////////////////////////
+  // Strip BOM
+  //////////////////////////////
+
+  it('should remove the BOM marker', function (done) {
+    var file = fs.readFileSync('tests/bom-utf8/starts-with-mixin-utf8-bom.scss').toString();
+    assert.equal(file.charCodeAt(0), 0xFEFF);
+    assert.notEqual(helpers.stripBom(file).charCodeAt(0), 0xFEFF);
+    done();
+  });
+
+  it('should throw an error if not passed a string', function (done) {
+    assert.throws(
+      function () {
+        helpers.stripBom(8);
+      }, Error
+    );
+    done();
+  });
+});