fix typo

- remove unwanted code
	- fix dropdown bug
	- add bar graph for test count

src/components/Devices.js

@@ -21,6 +21,8 @@ const Devices = () => {
 
     const changeDevice = ({ value }) => {
         setDevice(value);
+        setTestDate(null);
+        setCurTest(null);
         setDays([...new Set(allTests
             .filter((x) => x.deviceSerialNumber === value)
             .map(x => moment(x.testTime).format("YYYY-MM-DD")))]