diff -r 000000000000 -r 6474c204b198 testing/mozbase/mozinfo/tests/test.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/testing/mozbase/mozinfo/tests/test.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,88 @@
+#!/usr/bin/env python
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import json
+import mock
+import os
+import shutil
+import sys
+import tempfile
+import unittest
+import mozinfo
+
+class TestMozinfo(unittest.TestCase):
+    def setUp(self):
+        reload(mozinfo)
+        self.tempdir = os.path.abspath(tempfile.mkdtemp())
+
+        # When running from an objdir mozinfo will use a build generated json file
+        # instead of the ones created for testing. Prevent that from happening.
+        # See bug 896038 for details.
+        sys.modules['mozbuild'] = None
+
+    def tearDown(self):
+        shutil.rmtree(self.tempdir)
+        del sys.modules['mozbuild']
+
+    def test_basic(self):
+        """Test that mozinfo has a few attributes."""
+        self.assertNotEqual(mozinfo.os, None)
+        # should have isFoo == True where os == "foo"
+        self.assertTrue(getattr(mozinfo, "is" + mozinfo.os[0].upper() + mozinfo.os[1:]))
+
+    def test_update(self):
+        """Test that mozinfo.update works."""
+        mozinfo.update({"foo": 123})
+        self.assertEqual(mozinfo.info["foo"], 123)
+
+    def test_update_file(self):
+        """Test that mozinfo.update can load a JSON file."""
+        j = os.path.join(self.tempdir, "mozinfo.json")
+        with open(j, "w") as f:
+            f.write(json.dumps({"foo": "xyz"}))
+        mozinfo.update(j)
+        self.assertEqual(mozinfo.info["foo"], "xyz")
+
+    def test_update_file_invalid_json(self):
+        """Test that mozinfo.update handles invalid JSON correctly"""
+        j = os.path.join(self.tempdir,'test.json')
+        with open(j, 'w') as f:
+            f.write('invalid{"json":')
+        self.assertRaises(ValueError,mozinfo.update,[j])
+
+    def test_find_and_update_file(self):
+        """Test that mozinfo.find_and_update_from_json can
+        find mozinfo.json in a directory passed to it."""
+        j = os.path.join(self.tempdir, "mozinfo.json")
+        with open(j, "w") as f:
+            f.write(json.dumps({"foo": "abcdefg"}))
+        self.assertEqual(mozinfo.find_and_update_from_json(self.tempdir), j)
+        self.assertEqual(mozinfo.info["foo"], "abcdefg")
+
+    def test_find_and_update_file_invalid_json(self):
+        """Test that mozinfo.find_and_update_from_json can
+        handle invalid JSON"""
+        j = os.path.join(self.tempdir, "mozinfo.json")
+        with open(j, 'w') as f:
+            f.write('invalid{"json":')
+        self.assertRaises(ValueError, mozinfo.find_and_update_from_json, self.tempdir)
+
+
+    def test_find_and_update_file_mozbuild(self):
+        """Test that mozinfo.find_and_update_from_json can
+        find mozinfo.json using the mozbuild module."""
+        j = os.path.join(self.tempdir, "mozinfo.json")
+        with open(j, "w") as f:
+            f.write(json.dumps({"foo": "123456"}))
+        m = mock.MagicMock()
+        # Mock the value of MozbuildObject.from_environment().topobjdir.
+        m.MozbuildObject.from_environment.return_value.topobjdir = self.tempdir
+        with mock.patch.dict(sys.modules, {"mozbuild": m, "mozbuild.base": m}):
+            self.assertEqual(mozinfo.find_and_update_from_json(), j)
+        self.assertEqual(mozinfo.info["foo"], "123456")
+
+if __name__ == '__main__':
+    unittest.main()