Fix testrunner tests

Author: yanne

src/robotide/contrib/testrunner/usages.py

@@ -76,6 +76,7 @@
  -R --rerunfailed output  Select failed tests from an earlier output file to be
                           re-executed. Equivalent to selecting same tests
                           individually using --test option.
+    --runfailed output    Deprecated since RF 2.8.4. Use --rerunfailed instead.
  -c --critical tag *      Tests having given tag are considered critical. If no
                           critical tags are set, all tags are critical. Tags
                           can be given as a pattern like with --include.

utest/contrib/testrunner/test_pybot_arguments_validation.py

@@ -25,9 +25,6 @@ def test_valid_argument_with_value(self):
     def test_runfailed_argument_works(self):
         self._working_arguments('--runfailed output.xml')
 
-    def test_old_runmode_argument_works(self):
-        self._working_arguments('--runmode DryRun')
-
 
 if __name__ == '__main__':
-    unittest.main()
+    unittest.main()