Updated tests accordingly

src/test/java/de/rwu/easydrop/api/client/AmazonSellerTest.java

@@ -11,12 +11,14 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.mockito.MockitoAnnotations;
 
+import de.rwu.easydrop.model.Webshop;
+
 class AmazonSellerTest {
     private AmazonSeller demoSeller;
 
     private static String demoApiKey = "my-api-key";
     private static String demoApiUrl = "https://www.example.com/api";
-    private static String demoDataTarget = "Amazon";
+    private static Webshop demoDataTarget = Webshop.Amazon;
 
     @BeforeEach
     void setup() {
@@ -68,7 +70,7 @@ class AmazonSellerTest {
 
     @Test
     void getDataTarget_ReturnsExpectedDataOrigin() {
-        String dataTarget = demoSeller.getDataTarget();
+        Webshop dataTarget = demoSeller.getDataTarget();
         assertEquals(demoDataTarget, dataTarget);
     }