[CB-2213] Added tests for write and truncate.
[CB-2213] Added tests for write and truncate.

Also added a method to clear the status before each test.

apache/cordova-mobile-spec,corimf/cordova-mobile-spec,ollie314/cordova-mobile-spec,corimf/cordova-mobile-spec,polyvi/xface-mobile-spec,ollie314/cordova-mobile-spec,corimf/cordova-mobile-spec,corimf/cordova-mobile-spec,polyvi/xface-mobile-spec,ollie314/cordova-mobile-spec,apache/cordova-mobile-spec,apache/cordova-mobile-spec,lorinbeer/cordova-mobile-spec,apache/cordova-mobile-spec,corimf/cordova-mobile-spec,polyvi/xface-mobile-spec,apache/cordova-mobile-spec,ollie314/cordova-mobile-spec,ollie314/cordova-mobile-spec