feat(reporter): support source maps (rewrite stack traces)

Closes #594

Author: vojtajina

lib/reporter.js

@@ -1,20 +1,58 @@
+var util = require('util');
 var log = require('./logger').create('reporter');
 var MultiReporter = require('./reporters/multi');
 var baseReporterDecoratorFactory = require('./reporters/base').decoratorFactory;
+var SourceMapConsumer = require('source-map').SourceMapConsumer;
 
-var createErrorFormatter = function(basePath) {
-  var URL_REGEXP = new RegExp('http:\\/\\/[^\\/]*' +
-                              '\\/(base|absolute)([^\\?\\s\\:]*)(\\?\\w*)?', 'g');
+var createErrorFormatter = function(basePath, emitter, SourceMapConsumer) {
+  var lastServedFiles = [];
+
+  emitter.on('file_list_modified', function(filesPromise) {
+    filesPromise.then(function(files) {
+      lastServedFiles = files.served;
+    });
+  });
+
+  var findFile = function(path) {
+    for (var i = 0; i < lastServedFiles.length; i++) {
+      if (lastServedFiles[i].path === path) {
+        return lastServedFiles[i];
+      }
+    }
+    return null;
+  };
+
+  var URL_REGEXP = new RegExp('http:\\/\\/[^\\/]*\\/' +
+                              '(base|absolute)' + // prefix
+                              '([^\\?\\s\\:]*)' + // path
+                              '(\\?\\w*)?' +      // sha
+                              '(\\:(\\d+))?' +    // line
+                              '(\\:(\\d+))?' +    // column
+                              '', 'g');
 
   return function(msg, indentation) {
     // remove domain and timestamp from source files
     // and resolve base path / absolute path urls into absolute path
-    msg = (msg || '').replace(URL_REGEXP, function(full, prefix, path) {
+    msg = (msg || '').replace(URL_REGEXP, function(_, prefix, path, __, ___, line, ____, column) {
+
       if (prefix === 'base') {
-        return basePath + path;
-      } else if (prefix === 'absolute') {
-        return path;
+        path = basePath + path;
+      }
+
+      var file = findFile(path);
+
+      if (file && file.sourceMap) {
+        line = parseInt(line || '0', 10);
+        column = parseInt(column || '0', 10);
+
+        var smc = new SourceMapConsumer(file.sourceMap);
+        var original = smc.originalPositionFor({line: line, column: column});
+
+        return util.format('%s:%d:%d <- %s:%d:%d', path, line, column, original.source,
+            original.line, original.column);
       }
+
+      return path + (line ? ':' + line : '') + (column ? ':' + column : '');
     });
 
     // indent every line
@@ -26,11 +64,9 @@ var createErrorFormatter = function(basePath) {
   };
 };
 
-createErrorFormatter.$inject = ['config.basePath'];
-
 
 var createReporters = function(names, config, emitter, injector) {
-  var errorFormatter = createErrorFormatter(config.basePath, config.urlRoot);
+  var errorFormatter = createErrorFormatter(config.basePath, emitter, SourceMapConsumer);
   var reporters = [];
 
   // TODO(vojta): instantiate all reporters through DI
@@ -42,7 +78,7 @@ var createReporters = function(names, config, emitter, injector) {
 
     var locals = {
       baseReporterDecorator: ['factory', baseReporterDecoratorFactory],
-      formatError: ['factory', createErrorFormatter]
+      formatError: ['value', errorFormatter]
     };
 
     try {

package.json

@@ -119,7 +119,8 @@
     "log4js": "~0.6.3",
     "useragent": "~2.0.4",
     "graceful-fs": "~1.2.1",
-    "connect": "~2.8.4"
+    "connect": "~2.8.4",
+    "source-map": "~0.1.31"
   },
   "devDependencies": {
     "grunt": "~0.4",

test/unit/reporter.spec.coffee

@@ -2,7 +2,10 @@
 # lib/reporter.js module
 #==============================================================================
 describe 'reporter', ->
+  EventEmitter = require('events').EventEmitter
+  File = require('../../lib/file_list').File
   loadFile = require('mocks').loadFile
+  q = require 'q'
   m = null
 
   beforeEach ->
@@ -13,10 +16,11 @@ describe 'reporter', ->
   # formatError() [PRIVATE]
   #==============================================================================
   describe 'formatError', ->
-    formatError = null
+    formatError = emitter = null
 
     beforeEach ->
-      formatError = m.createErrorFormatter '', '/'
+      emitter = new EventEmitter
+      formatError = m.createErrorFormatter '', emitter
 
 
     it 'should indent', ->
@@ -52,7 +56,7 @@ describe 'reporter', ->
 
 
     it 'should restore base paths', ->
-      formatError = m.createErrorFormatter '/some/base', '/'
+      formatError = m.createErrorFormatter '/some/base', emitter
       expect(formatError 'at http://localhost:123/base/a.js?123').to.equal 'at /some/base/a.js\n'
 
 
@@ -64,3 +68,27 @@ describe 'reporter', ->
     it 'should preserve line numbers', ->
       ERROR = 'at http://local:1233/absolute/usr/path.js?6e31cb249ee5b32d91f37ea516ca0f84bddc5aa9:2'
       expect(formatError ERROR).to.equal 'at /usr/path.js:2\n'
+
+
+    describe 'source maps', ->
+
+      class MockSourceMapConsumer
+        constructor: (sourceMap) ->
+          @source = sourceMap.replace 'SOURCE MAP ', '/original/'
+        originalPositionFor: (position) ->
+          source: @source
+          line: position.line + 2
+          column: position.column + 2
+
+      it 'should rewrite stack traces', (done) ->
+        formatError = m.createErrorFormatter '/some/base', emitter, MockSourceMapConsumer
+        servedFiles = [new File('/some/base/a.js'), new File('/some/base/b.js')]
+        servedFiles[0].sourceMap = 'SOURCE MAP a.js'
+        servedFiles[1].sourceMap = 'SOURCE MAP b.js'
+
+        emitter.emit 'file_list_modified', q(served: servedFiles)
+
+        scheduleNextTick ->
+          ERROR = 'at http://localhost:123/base/b.js:2:6'
+          expect(formatError ERROR).to.equal 'at /some/base/b.js:2:6 <- /original/b.js:4:8\n'
+          done()