Fix typo. (#611)

diff --git a/mobly/test_runner.py b/mobly/test_runner.py
index 77db5cf..f67dede 100644
--- a/mobly/test_runner.py
+++ b/mobly/test_runner.py
@@ -74,7 +74,7 @@
     for config in test_configs:
         runner = TestRunner(log_dir=config.log_path,
                             test_bed_name=config.test_bed_name)
-        with runner.mobly_loggger():
+        with runner.mobly_logger():
             runner.add_test_class(config, test_class, tests)
             try:
                 runner.run()
diff --git a/tests/mobly/test_runner_test.py b/tests/mobly/test_runner_test.py
index 0987454..e681dec 100755
--- a/tests/mobly/test_runner_test.py
+++ b/tests/mobly/test_runner_test.py
@@ -274,6 +274,41 @@
         test_runner.main(['-c', 'some/path/foo.yaml', '-b', 'hello'])
         mock_config.assert_called_with('some/path/foo.yaml', None)
 
+    @mock.patch('mobly.test_runner._find_test_class',
+                return_value=integration_test.IntegrationTest)
+    @mock.patch('sys.exit')
+    def test_main(self, mock_exit, mock_find_test):
+        tmp_file_path = os.path.join(self.tmp_dir, 'config.yml')
+        with io.open(tmp_file_path, 'w', encoding='utf-8') as f:
+            f.write(u"""
+                TestBeds:
+                    # A test bed where adb will find Android devices.
+                    - Name: SampleTestBed
+                      Controllers:
+                          MagicDevice: '*'
+                      TestParams:
+                          icecream: 42
+                          extra_param: 'haha'
+            """)
+        test_runner.main(['-c', tmp_file_path])
+        mock_exit.assert_not_called()
+
+    @mock.patch('mobly.test_runner._find_test_class',
+                return_value=integration_test.IntegrationTest)
+    @mock.patch('sys.exit')
+    def test_main_with_failures(self, mock_exit, mock_find_test):
+        tmp_file_path = os.path.join(self.tmp_dir, 'config.yml')
+        with io.open(tmp_file_path, 'w', encoding='utf-8') as f:
+            f.write(u"""
+                TestBeds:
+                    # A test bed where adb will find Android devices.
+                    - Name: SampleTestBed
+                      Controllers:
+                          MagicDevice: '*'
+            """)
+        test_runner.main(['-c', tmp_file_path])
+        mock_exit.assert_called_once_with(1)
+
 
 if __name__ == "__main__":
     unittest.main()