diff --git a/src/main/java/de/rwu/easydrop/util/Config.java b/src/main/java/de/rwu/easydrop/util/Config.java
index 68be4a4..32cce6a 100644
--- a/src/main/java/de/rwu/easydrop/util/Config.java
+++ b/src/main/java/de/rwu/easydrop/util/Config.java
@@ -109,4 +109,11 @@ public final class Config {
     public void setProperty(final String key, final String value) {
         properties.setProperty(key, value);
     }
+
+    /**
+     * Resets the config's properties.
+     */
+    public void reset() {
+        properties = null;
+    }
 }
diff --git a/src/test/java/de/rwu/easydrop/api/dto/ProductDTOTest.java b/src/test/java/de/rwu/easydrop/api/dto/ProductDTOTest.java
index 9d5917a..1e16d7c 100644
--- a/src/test/java/de/rwu/easydrop/api/dto/ProductDTOTest.java
+++ b/src/test/java/de/rwu/easydrop/api/dto/ProductDTOTest.java
@@ -1,33 +1,56 @@
 package de.rwu.easydrop.api.dto;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
 import org.junit.jupiter.api.Test;
 
 class ProductDTOTest {
+
     @Test
-    void testToString1() {
-        ProductDTO product1 = new ProductDTO("12345", "Amazon");
-        product1.setMerchant("Merchant A");
-        product1.setCurrentPrice(19.99);
-        product1.setAvailable(true);
+    void constructor_SetsProductIdAndDataOrigin() {
+        // Arrange
+        String productId = "12345";
+        String dataOrigin = "Amazon";
 
-        String expectedString1 = "ProductDTO{12345 from Merchant A (Amazon) at 19,99 € (available: yes)}";
-        String result1 = product1.toString();
+        // Act
+        ProductDTO productDTO = new ProductDTO(productId, dataOrigin);
 
-        assertEquals(expectedString1, result1);
+        // Assert
+        assertEquals(productId, productDTO.getProductId());
+        assertEquals(dataOrigin, productDTO.getDataOrigin());
     }
 
     @Test
-    void testToString2() {
-        ProductDTO product2 = new ProductDTO("67890", "eBay");
-        product2.setMerchant("Merchant B");
-        product2.setCurrentPrice(9.99);
-        product2.setAvailable(false);
+    void gettersAndSetters_WorkAsExpected() {
+        // Arrange
+        ProductDTO productDTO = new ProductDTO("12345", "Amazon");
 
-        String expectedString2 = "ProductDTO{67890 from Merchant B (eBay) at 9,99 € (available: no)}";
-        String result2 = product2.toString();
+        // Act and Assert
+        assertEquals("12345", productDTO.getProductId());
+        assertEquals("Amazon", productDTO.getDataOrigin());
 
-        assertEquals(expectedString2, result2);
+        // Modify fields
+        productDTO.setProductId("54321");
+        productDTO.setDataOrigin("eBay");
+
+        // Assert
+        assertEquals("54321", productDTO.getProductId());
+        assertEquals("eBay", productDTO.getDataOrigin());
+    }
+
+    @Test
+    void defaultConstructor_SetsDefaultValues() {
+        // Act
+        ProductDTO productDTO = new ProductDTO(null, null);
+
+        // Assert
+        assertNull(productDTO.getProductId());
+        assertNull(productDTO.getDataOrigin());
+        assertEquals(0.0, productDTO.getCurrentPrice());
+        assertNull(productDTO.getMerchant());
+        assertEquals(0.0, productDTO.getDeliveryPrice());
+        assertFalse(productDTO.isAvailable());
     }
 }
diff --git a/src/test/java/de/rwu/easydrop/model/ProductTest.java b/src/test/java/de/rwu/easydrop/model/ProductTest.java
new file mode 100644
index 0000000..1845b65
--- /dev/null
+++ b/src/test/java/de/rwu/easydrop/model/ProductTest.java
@@ -0,0 +1,75 @@
+package de.rwu.easydrop.model;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+class ProductTest {
+    @Test
+    void testToString1() {
+        Product product1 = new Product();
+        product1.setDataOrigin("Amazon");
+        product1.setProductId("12345");
+        product1.setMerchant("Merchant A");
+        product1.setCurrentPrice(19.99);
+        product1.setAvailable(true);
+
+        String expectedString1 = "Product: [12345 from Merchant A (Amazon) at 19,99 € (available: yes)]";
+        String result1 = product1.toString();
+
+        assertEquals(expectedString1, result1);
+    }
+
+    @Test
+    void testToString2() {
+        Product product2 = new Product();
+        product2.setDataOrigin("eBay");
+        product2.setProductId("67890");
+        product2.setMerchant("Merchant B");
+        product2.setCurrentPrice(9.99);
+        product2.setAvailable(false);
+
+        String expectedString2 = "Product: [67890 from Merchant B (eBay) at 9,99 € (available: no)]";
+        String result2 = product2.toString();
+
+        assertEquals(expectedString2, result2);
+    }
+
+    @Test
+    void gettersAndSetters_WorkAsExpected() {
+        // Arrange
+        Product product = new Product();
+        product.setDataOrigin("Amazon");
+        product.setProductId("12345");
+        product.setCurrentPrice(9.99);
+        product.setMerchant("Example Merchant");
+        product.setDeliveryPrice(2.50);
+        product.setAvailable(true);
+
+        // Act and Assert
+        assertEquals("Amazon", product.getDataOrigin());
+        assertEquals("12345", product.getProductId());
+        assertEquals(9.99, product.getCurrentPrice());
+        assertEquals("Example Merchant", product.getMerchant());
+        assertEquals(2.50, product.getDeliveryPrice());
+        assertTrue(product.isAvailable());
+
+        // Modify fields
+        product.setDataOrigin("eBay");
+        product.setProductId("54321");
+        product.setCurrentPrice(19.99);
+        product.setMerchant("New Merchant");
+        product.setDeliveryPrice(3.50);
+        product.setAvailable(false);
+
+        // Assert
+        assertEquals("eBay", product.getDataOrigin());
+        assertEquals("54321", product.getProductId());
+        assertEquals(19.99, product.getCurrentPrice());
+        assertEquals("New Merchant", product.getMerchant());
+        assertEquals(3.50, product.getDeliveryPrice());
+        assertFalse(product.isAvailable());
+    }
+}
diff --git a/src/test/java/de/rwu/easydrop/util/ConfigImplTest.java b/src/test/java/de/rwu/easydrop/util/ConfigImplTest.java
index 0c5041e..59cece7 100644
--- a/src/test/java/de/rwu/easydrop/util/ConfigImplTest.java
+++ b/src/test/java/de/rwu/easydrop/util/ConfigImplTest.java
@@ -1,6 +1,7 @@
 package de.rwu.easydrop.util;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.fail;
 
@@ -34,7 +35,9 @@ class ConfigImplTest {
     }
 
     @Test
-    void testGetProperty_ConfigNotLoaded() {
+    void testGetProperty_ConfigNotLoaded() throws Exception {
+        config.reset();
+
         NoSuchElementException exception = assertThrows(NoSuchElementException.class, () -> {
             config.getProperty(TESTDATA_KEY);
         });
@@ -92,4 +95,19 @@ class ConfigImplTest {
 
         assertEquals("Couldn't load required config file", exception.getMessage());
     }
+
+    @Test
+    void testReset() throws ConfigurationException {
+        config.setConfigLocation("src/test/resources/testdata.properties");
+        config.loadConfig();
+
+        assertNotNull(config.getProperty(TESTDATA_KEY));
+        config.reset();
+
+        NoSuchElementException exception = assertThrows(NoSuchElementException.class, () -> {
+            config.getProperty(TESTDATA_KEY);
+        });
+
+        assertEquals("Config has not been loaded", exception.getMessage());
+    }
 }