diff --git a/karma/tests/work_packages/helpers/api-helper-test.js b/karma/tests/work_packages/helpers/api-helper-test.js
new file mode 100644
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+++ b/karma/tests/work_packages/helpers/api-helper-test.js
@@ -0,0 +1,100 @@
+//-- copyright
+// OpenProject is a project management system.
+// Copyright (C) 2012-2014 the OpenProject Foundation (OPF)
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License version 3.
+//
+// OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+// Copyright (C) 2006-2013 Jean-Philippe Lang
+// Copyright (C) 2010-2013 the ChiliProject Team
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+//
+// See doc/COPYRIGHT.rdoc for more details.
+//++
+
+/*jshint expr: true*/
+
+describe('API helper', function() {
+  var ApiHelper;
+
+  beforeEach(module('openproject.helpers',
+                    'openproject.workPackages.services'));
+  beforeEach(inject(function(_ApiHelper_) {
+    ApiHelper = _ApiHelper_;
+  }));
+
+  function createErrorObject(status, statusText, responseText) {
+    var error = new Object();
+
+    error.status = status;
+    error.statusText = statusText;
+    error.responseText = responseText;
+
+    return error;
+  }
+
+  describe('500', function() {
+    var error = createErrorObject(500, "Internal Server Error");
+
+    it('should return status text', function() {
+      expect(ApiHelper.getErrorMessage(error)).to.eq(error.statusText);
+    });
+  });
+
+  describe('other codes', function() {
+    function createApiErrorObject(errorIdentifier, message, multiple) {
+      var apiError = new Object();
+
+      apiError._type = 'Error';
+      apiError.errorIdentifier = (multiple) ? 'urn:openproject-org:api:v3:errors:MultipleErrors' : errorIdentifier;
+      apiError.message = message;
+
+      if (multiple) {
+        apiError._embedded = { errors: [] };
+
+        for (var x=0; x < 2; x++) {
+          apiError._embedded.errors.push(createApiErrorObject(errorIdentifier, message));
+        }
+      }
+
+      return apiError;
+    }
+
+    describe('single error', function() {
+      var apiError = createApiErrorObject('NotFound', 'Not found');
+      var error = createErrorObject(404, null, JSON.stringify(apiError));
+      var expectedResult = 'Not found.';
+
+      it('should return api error message', function() {
+        expect(ApiHelper.getErrorMessage(error)).to.eq(expectedResult);
+      });
+    });
+
+    describe('multiple errors', function() {
+      var errorMessage = 'This is an error message';
+      var apiError = createApiErrorObject('PropertyIsReadOnly', errorMessage, true);
+      var error = createErrorObject(404, null, JSON.stringify(apiError));
+
+      it('should return concatenated api error messages', function() {
+        var messages = [];
+        var expectedResult = errorMessage + '. ' + errorMessage + '.';
+
+        expect(ApiHelper.getErrorMessage(error)).to.eq(expectedResult);
+      });
+    });
+  });
+});