revised all test for setDevices now testing if every installed devices has the right instance & added productive code

src/main/java/BordComputer.java

@@ -11,7 +11,7 @@ public class BordComputer {
     Device[] installedDevices;
     Device activeDevice = null;
 
-    public void readConfig() {
+    public void readConfig() throws ClassNotFoundException, InvocationTargetException, NoSuchMethodException, InstantiationException, IllegalAccessException {
 
         try (FileReader reader = new FileReader("Geraete.config")) {
             Properties properties = new Properties();
@@ -20,16 +20,17 @@ public class BordComputer {
             Arrays.sort(values);
             deviceNames = new String[values.length];
             System.arraycopy(values, 0, deviceNames, 0, properties.size());
-            installedDevices=new Device[values.length];
+            installedDevices = new Device[values.length];
         } catch (Exception e) {
             e.printStackTrace();
         }
-        activeDevice =installedDevices[0];
+        setDevices();
+        activeDevice = installedDevices[0];
     }
 
     public void setDevices() throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException, ClassNotFoundException {
         Class<?> c;
-        for(int i = 0;i < deviceNames.length; i++) {
+        for (int i = 0; i < deviceNames.length; i++) {
             c = Class.forName(deviceNames[i]);
             installedDevices[i] = (Device) c.getConstructor().newInstance();
         }

src/test/java/BordComputerTest.java

@@ -1,5 +1,7 @@
 import device.Device;
+import device.cdPlayer.CDPlayer;
 import device.radioPlayer.RadioPlayer;
+import device.usbPlayer.UsbPlayer;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -35,7 +37,7 @@ class BordComputerTest {
         }
     }
 
-    static Stream<Arguments> readConfigOptions() {
+    static Stream<Arguments> readConfigOptions() throws ClassNotFoundException, InvocationTargetException, NoSuchMethodException, InstantiationException, IllegalAccessException {
         BordComputer bc1 = new BordComputer();
         bc1.readConfig();
 
@@ -50,24 +52,24 @@ class BordComputerTest {
 
     @ParameterizedTest
     @MethodSource("setDevicesOptions")
-    void setDevicesTest(String testName, BordComputer testBc, String testTyp) {
-        Device dev = null;
-        if(testTyp.equals("0")) dev = testBc.installedDevices[0];
-        if(testTyp.equals("1")) dev = testBc.installedDevices[1];
-        if(testTyp.equals("2")) dev = testBc.installedDevices[2];
-        assertThat(dev).describedAs(testName).isNotEqualTo(null);
+    void setDevicesTest(String testName, BordComputer testBc, String testTyp, Boolean bool) {
+        Boolean boolActual = null;
+        if (testTyp.equals("0")) boolActual = (testBc.installedDevices[0] instanceof CDPlayer);
+        if (testTyp.equals("1")) boolActual = (testBc.installedDevices[1] instanceof RadioPlayer);
+        if (testTyp.equals("2")) boolActual = (testBc.installedDevices[2] instanceof UsbPlayer);
+        assertThat(boolActual).describedAs(testName).isEqualTo(bool);
     }
 
     static Stream<Arguments> setDevicesOptions() throws ClassNotFoundException, InvocationTargetException, NoSuchMethodException, InstantiationException, IllegalAccessException {
         BordComputer bc = new BordComputer();
         bc.readConfig();
-        bc.setDevices();
         return Stream.of(
-                Arguments.of("Test if installedDevices[0] is not null", bc, "0"),
-                Arguments.of("Test if installedDevices[1] is not null", bc, "1"),
-                Arguments.of("Test if installedDevices[2] is not null", bc, "2")
+                Arguments.of("Test if installedDevices[0] is instance of CDPlayer", bc, "0", true),
+                Arguments.of("Test if installedDevices[1] is instance of RadioPlayer", bc, "1", true),
+                Arguments.of("Test if installedDevices[2] is instance of UsbPlayer", bc, "2", true)
         );
     }
+
     public int fileReaderCount() {
         int count = 0;
         try (FileReader reader = new FileReader("Geraete.config")) {
@@ -76,6 +78,7 @@ class BordComputerTest {
             count = properties.size();
         } catch (IOException e) {
             e.printStackTrace();
-        } return count;
+        }
+        return count;
     }
 }