Throw error on node (fix #46)

lib/pixrem.js

@@ -79,7 +79,7 @@ module.exports = postcss.plugin('pixrem', function (opts) {
             value = value.replace(REGEX, function ($1) {
               // Round decimal pixels down to match webkit and opera behavior:
               // http://tylertate.com/blog/2012/01/05/subpixel-rounding.html
-              return Math.floor(parseFloat($1) * toPx(options.rootValue, result)) + 'px';
+              return Math.floor(parseFloat($1) * toPx(options.rootValue, decl, result)) + 'px';
             });
 
             if (options.replace) {
@@ -122,7 +122,7 @@ function detectBrowser (browsers, browserQuery) {
 }
 
 // Return a unitless pixel value from any root font-size value.
-function toPx (value, result) {
+function toPx (value, decl, result) {
   value = (typeof value === 'string' && value.indexOf('calc(') !== -1) ? calc(value) : value;
   var parts = /^(\d*\.?\d+)([a-zA-Z%]*)$/.exec(value);
   if (parts !== null) {
@@ -143,7 +143,7 @@ function toPx (value, result) {
       return BASE_FONT_SIZE;
     }
   } else {
-    throw new Error('Root font-size is invalid');
+    throw decl.error('Root font-size is invalid', {plugin: 'pixrem'});
   }
 }
 

test/test.js

@@ -193,14 +193,15 @@ describe('pixrem', function () {
     assert.equal(processed, expected);
   });
 
-  it('should throw error when root font-size is invalid', function () {
+  it('should throw error when root font-size is invalid', function (done) {
     var css = 'html { font-size: calc(1em + 2px) } .rule { font-size: 2rem; }';
-    var processed = function () {
-      return postcss([pixrem]).process(css).css;
-    };
-    assert.throws(processed, function (err) {
-      return err.message === 'Root font-size is invalid';
-    });
+    postcss([pixrem]).process(css).then(function () {
+      done('should not run');
+    }).catch(function (err) {
+      assert.equal(err.name, 'CssSyntaxError');
+      assert.equal(err.reason, 'Root font-size is invalid');
+      done();
+    }).catch(done);
   });
 
   it('should reduce line-breaks when inserting new node', function () {