diff --git a/react-packager/src/Activity/__tests__/Activity-test.js b/react-packager/src/Activity/__tests__/Activity-test.js
index bd0265f9..7fe31614 100644
--- a/react-packager/src/Activity/__tests__/Activity-test.js
+++ b/react-packager/src/Activity/__tests__/Activity-test.js
@@ -10,6 +10,7 @@ describe('Activity', function() {
   beforeEach(function() {
     console.log = jest.genMockFn();
     Activity = require('../');
+    jest.runOnlyPendingTimers();
   });
 
   afterEach(function() {
@@ -60,12 +61,15 @@ describe('Activity', function() {
 
       expect(function() {
         Activity.endEvent(eid);
-      }).toThrow('event(1) has already ended!');
+      }).toThrow('event(3) has already ended!');
+
+      jest.runOnlyPendingTimers();
     });
   });
 
   describe('signal', function() {
     it('writes a SIGNAL event out to the console', function() {
+
       var EVENT_NAME = 'EVENT_NAME';
       var DATA = {someData: 42};
 
diff --git a/react-packager/src/DependencyResolver/haste/DependencyGraph/__tests__/DependencyGraph-test.js b/react-packager/src/DependencyResolver/haste/DependencyGraph/__tests__/DependencyGraph-test.js
index 1c268c6b..eb839296 100644
--- a/react-packager/src/DependencyResolver/haste/DependencyGraph/__tests__/DependencyGraph-test.js
+++ b/react-packager/src/DependencyResolver/haste/DependencyGraph/__tests__/DependencyGraph-test.js
@@ -5,7 +5,6 @@ jest
   .dontMock('q')
   .dontMock('path')
   .dontMock('absolute-path')
-  .dontMock('../../../../fb-path-utils')
   .dontMock('../docblock')
   .setMock('../../../ModuleDescriptor', function(data) {return data;});
 
diff --git a/react-packager/src/FileWatcher/__mocks__/sane.js b/react-packager/src/FileWatcher/__mocks__/sane.js
new file mode 100644
index 00000000..20dda2a2
--- /dev/null
+++ b/react-packager/src/FileWatcher/__mocks__/sane.js
@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports = {
+  WatchmanWatcher: jest.genMockFromModule('sane/src/watchman_watcher')
+};
diff --git a/react-packager/src/JSTransformer/__mocks__/q.js b/react-packager/src/JSTransformer/__mocks__/q.js
new file mode 100644
index 00000000..3d4d21f1
--- /dev/null
+++ b/react-packager/src/JSTransformer/__mocks__/q.js
@@ -0,0 +1,6 @@
+'use strict';
+
+// Bug with Jest because we're going to the node_modules that is a sibling
+// of what jest thinks our root (the dir with the package.json) should be.
+
+module.exports = require.requireActual('q');
diff --git a/react-packager/src/JSTransformer/__mocks__/underscore.js b/react-packager/src/JSTransformer/__mocks__/underscore.js
new file mode 100644
index 00000000..a985ab20
--- /dev/null
+++ b/react-packager/src/JSTransformer/__mocks__/underscore.js
@@ -0,0 +1,5 @@
+'use strict';
+
+// Bug with Jest because we're going to the node_modules that is a sibling
+// of what jest thinks our root (the dir with the package.json) should be.
+module.exports = require.requireActual('underscore');
diff --git a/react-packager/src/JSTransformer/__tests__/Cache-test.js b/react-packager/src/JSTransformer/__tests__/Cache-test.js
index 232d6ff4..97a50097 100644
--- a/react-packager/src/JSTransformer/__tests__/Cache-test.js
+++ b/react-packager/src/JSTransformer/__tests__/Cache-test.js
@@ -3,7 +3,6 @@
 jest
   .dontMock('underscore')
   .dontMock('path')
-  .dontMock('q')
   .dontMock('absolute-path')
   .dontMock('../Cache');
 
@@ -194,7 +193,7 @@ describe('JSTransformer Cache', function() {
         return q('baz value');
       });
 
-      jest.runAllTimers();
+      jest.runAllTicks();
       expect(fs.writeFile).toBeCalled();
     });
   });
diff --git a/react-packager/src/JSTransformer/__tests__/Transformer-test.js b/react-packager/src/JSTransformer/__tests__/Transformer-test.js
index 6c9c6644..36d81d8f 100644
--- a/react-packager/src/JSTransformer/__tests__/Transformer-test.js
+++ b/react-packager/src/JSTransformer/__tests__/Transformer-test.js
@@ -2,7 +2,6 @@
 
 jest
   .dontMock('worker-farm')
-  .dontMock('q')
   .dontMock('os')
   .dontMock('../index');
 
@@ -36,7 +35,7 @@ describe('Transformer', function() {
       callback(null, 'content');
     });
 
-    return new Transformer(OPTIONS).loadFileAndTransform([], 'file', {})
+    return new Transformer(OPTIONS).loadFileAndTransform('file')
       .then(function(data) {
         expect(data).toEqual({
           code: 'transformed',
@@ -59,7 +58,7 @@ describe('Transformer', function() {
       callback(null, {error: esprimaError});
     });
 
-    return new Transformer(OPTIONS).loadFileAndTransform([], 'foo-file.js', {})
+    return new Transformer(OPTIONS).loadFileAndTransform('foo-file.js')
       .catch(function(error) {
         expect(error.type).toEqual('TransformError');
         expect(error.snippet).toEqual([
diff --git a/react-packager/src/JSTransformer/index.js b/react-packager/src/JSTransformer/index.js
index e3e713ee..87cb6e1a 100644
--- a/react-packager/src/JSTransformer/index.js
+++ b/react-packager/src/JSTransformer/index.js
@@ -78,11 +78,7 @@ Transformer.prototype.invalidateFile = function(filePath) {
   this._cache.invalidate(filePath);
 };
 
-Transformer.prototype.loadFileAndTransform = function(
-  transformSets,
-  filePath,
-  options
-) {
+Transformer.prototype.loadFileAndTransform = function(filePath) {
   if (this._failedToStart) {
     return this._failedToStart;
   }
@@ -92,15 +88,14 @@ Transformer.prototype.loadFileAndTransform = function(
     return readFile(filePath)
       .then(function(buffer) {
         var sourceCode = buffer.toString();
-        var opts = _.extend({}, options, {filename: filePath});
+
         return q.nfbind(workers)({
-          transformSets: transformSets,
           sourceCode: sourceCode,
-          options: opts,
+          filename: filePath,
         }).then(
           function(res) {
             if (res.error) {
-              throw formatEsprimaError(res.error, filePath, sourceCode);
+              throw formatError(res.error, filePath, sourceCode);
             }
 
             return {
@@ -117,11 +112,26 @@ Transformer.prototype.loadFileAndTransform = function(
 function TransformError() {}
 util.inherits(TransformError, SyntaxError);
 
-function formatEsprimaError(err, filename, source) {
-  if (!(err.lineNumber && err.column)) {
-    return err;
+function formatError(err, filename, source) {
+  if (err.lineNumber && err.column) {
+    return formatEsprimaError(err, filename, source);
+  } else {
+    return formatGenericError(err, filename, source);
   }
+}
 
+function formatGenericError(err, filename) {
+  var msg = 'TransformError: ' + filename + ': ' + err.message;
+  var error = new TransformError();
+  var stack = err.stack.split('\n').slice(0, -1);
+  stack.push(msg);
+  error.stack = stack.join('\n');
+  error.message = msg;
+  error.type = 'TransformError';
+  return error;
+}
+
+function formatEsprimaError(err, filename, source) {
   var stack = err.stack.split('\n');
   stack.shift();
 
diff --git a/react-packager/src/Packager/__tests__/Package-test.js b/react-packager/src/Packager/__tests__/Package-test.js
index d269eb57..74a2f437 100644
--- a/react-packager/src/Packager/__tests__/Package-test.js
+++ b/react-packager/src/Packager/__tests__/Package-test.js
@@ -1,10 +1,6 @@
 'use strict';
 
-jest
-  .dontMock('underscore')
-  .dontMock('../base64-vlq')
-  .dontMock('source-map')
-  .dontMock('../Package');
+jest.autoMockOff();
 
 var SourceMapGenerator = require('source-map').SourceMapGenerator;
 
diff --git a/react-packager/src/Packager/__tests__/Packager-test.js b/react-packager/src/Packager/__tests__/Packager-test.js
index 21af12ca..2e43e91a 100644
--- a/react-packager/src/Packager/__tests__/Packager-test.js
+++ b/react-packager/src/Packager/__tests__/Packager-test.js
@@ -49,7 +49,7 @@ describe('Packager', function() {
     });
 
     require('../../JSTransformer').prototype.loadFileAndTransform
-      .mockImpl(function(tsets, path) {
+      .mockImpl(function(path) {
         return q({
           code: 'transformed ' + path,
           sourceCode: 'source ' + path,
diff --git a/react-packager/src/Packager/index.js b/react-packager/src/Packager/index.js
index 42295acc..123a3913 100644
--- a/react-packager/src/Packager/index.js
+++ b/react-packager/src/Packager/index.js
@@ -126,9 +126,7 @@ Packager.prototype.getDependencies = function(main) {
 Packager.prototype._transformModule = function(module) {
   var resolver = this._resolver;
   return this._transformer.loadFileAndTransform(
-    ['es6'],
-    path.resolve(module.path),
-    this._opts.transformer || {}
+    path.resolve(module.path)
   ).then(function(transformed) {
     return _.extend(
       {},
diff --git a/react-packager/src/Server/__tests__/Server-test.js b/react-packager/src/Server/__tests__/Server-test.js
index a9951f60..e6020c79 100644
--- a/react-packager/src/Server/__tests__/Server-test.js
+++ b/react-packager/src/Server/__tests__/Server-test.js
@@ -3,9 +3,13 @@
 jest.setMock('worker-farm', function() { return function() {}; })
     .dontMock('q')
     .dontMock('os')
-    .dontMock('errno/custom')
     .dontMock('path')
     .dontMock('url')
+    .setMock('timers', {
+      setImmediate: function(fn) {
+        return setTimeout(fn, 0);
+      }
+    })
     .dontMock('../');
 
 var q = require('q');
@@ -75,16 +79,16 @@ describe('processRequest', function() {
   });
 
   pit('returns sourcemap on request of *.map', function() {
-    makeRequest(
+    return makeRequest(
       requestHandler,
       'mybundle.includeRequire.runModule.bundle.map'
     ).then(function(response) {
-      expect(response).toEqual('this is the source map');
+      expect(response).toEqual('"this is the source map"');
     });
   });
 
   pit('watches all files in projectRoot', function() {
-    makeRequest(
+    return makeRequest(
       requestHandler,
       'mybundle.includeRequire.runModule.bundle'
     ).then(function(response) {
@@ -107,7 +111,7 @@ describe('processRequest', function() {
     });
 
     pit('invalides files in package when file is updated', function() {
-      makeRequest(
+      return makeRequest(
         requestHandler,
         'mybundle.includeRequire.runModule.bundle'
       ).then(function(response) {
diff --git a/react-packager/src/Server/index.js b/react-packager/src/Server/index.js
index 14b18c96..accce205 100644
--- a/react-packager/src/Server/index.js
+++ b/react-packager/src/Server/index.js
@@ -6,6 +6,7 @@ var declareOpts = require('../lib/declareOpts');
 var FileWatcher = require('../FileWatcher');
 var Packager = require('../Packager');
 var Activity = require('../Activity');
+var setImmediate = require('timers').setImmediate;
 var q = require('q');
 
 module.exports = Server;
diff --git a/transformer.js b/transformer.js
index ffcb80e2..acb586d7 100644
--- a/transformer.js
+++ b/transformer.js
@@ -16,10 +16,11 @@ var staticTypeSyntax =
 var visitorList = reactVisitors;
 
 
-function transform(transformSets, srcTxt) {
+function transform(srcTxt, filename) {
   var options = {
     es3: true,
-    sourceType: 'nonStrictModule'
+    sourceType: 'nonStrictModule',
+    filename: filename,
   };
 
   // These tranforms mostly just erase type annotations and static typing
@@ -42,8 +43,8 @@ module.exports = function(data, callback) {
   var result;
   try {
     result = transform(
-      data.transformSets,
-      data.sourceCode
+      data.sourceCode,
+      data.filename
     );
   } catch (e) {
     return callback(null, {