Merge branch '#37-eBay-Product-API' into 'dev'

eBay Product API

See merge request team1/sandbox2!3

.vscode/settings.json

@@ -1,3 +1,8 @@
 {
-    "java.configuration.updateBuildConfiguration": "automatic"
+  "java.configuration.updateBuildConfiguration": "automatic",
-}
+  "sonarlint.connectedMode.project": {
+    "connectionId": "LocalSonarQube",
+    "projectKey": "EasyDrop"
+  },
+  "java.debug.settings.onBuildFailureProceed": true
+}

CHANGELOG.md

@@ -1,10 +1,34 @@
 # Changelog
 
+## 0.2.0-SNAPSHOT
+
+### Added
+
+- `EbayItemDataSource` (#37)
+- `Product` class
+- Mapping between Product and its corresponding DTO
+- Dependencies: Lombok for easier notation, JUnit 5 Params for repetitive tests
+- Product Validation
+- Product Retrieval
+- Tests
+
+### Changed
+
+- `AbstractDataSource` between DataSource interface and implementations to minimize code duplication
+  - Affects AmazonProductDataSource and related tests (~ #39)
+- Testing resources moved to more intuitive location
+- Demo `Main` method now uses proper Product retrieval
+
+### Fixed
+
+- Logback configuration is now linked correctly
+- Config now properly adheres to singleton pattern
+
 ## 0.1.0
 
 ### Added
 
-- (DataSource) → AmazonProductDataSource as first external data source (#39)
+- (DataSource) → `AmazonProductDataSource` as first external data source (#39)
-- ProductDTO as data holder structure for data from external sources (~ #39)
+- `ProductDTO` as data holder structure for data from external sources (~ #39)
 - Config for credential, base URLs etc. (~ #39)
 - FormattingUtil for formatting price strings (~ #39)

SampleResponses/eBayProductAPISample.json

@@ -0,0 +1,133 @@
+{
+  "href": "https://api.ebay.com/buy/browse/v1/item_summary/search?q=drone&limit=1&offset=0",
+  "total": 260202,
+  "next": "https://api.ebay.com/buy/browse/v1/item_summary/search?q=drone&limit=1&offset=1",
+  "limit": 3,
+  "offset": 0,
+  "itemSummaries": [
+    {
+      "itemId": "v1|1**********1|0",
+      "title": "Syma X5SW-V3 Wifi FPV RC Drone Quadcopter 2.4Ghz 6-Axis Gyro with Headless Mode",
+      "leafCategoryIds": ["179697", "182186"],
+      "categories": [
+        {
+          "categoryId": "179697",
+          "categoryName": "Camera Drones"
+        },
+        {
+          "categoryId": "182186",
+          "categoryName": "Other RC Model Vehicles & Kits"
+        },
+        {
+          "categoryId": "2562",
+          "categoryName": "Radio Control & Control Line"
+        },
+        {
+          "categoryId": "220",
+          "categoryName": "Toys & Hobbies"
+        },
+        {
+          "categoryId": "625",
+          "categoryName": "Cameras & Photo"
+        },
+        {
+          "categoryId": "182181",
+          "categoryName": "RC Model Vehicles & Kits"
+        }
+      ],
+      "image": {
+        "imageUrl": "https://i.ebayimg.com/thumbs/images/g/n**************a/s-***5.jpg"
+      },
+      "price": {
+        "value": "59.99",
+        "currency": "USD"
+      },
+      "itemHref": "https://api.ebay.com/buy/browse/v1/item/v1******************0",
+      "seller": {
+        "username": "m********e",
+        "feedbackPercentage": "98.6",
+        "feedbackScore": 130000
+      },
+      "marketingPrice": {
+        "originalPrice": {
+          "value": "74.99",
+          "currency": "USD"
+        },
+        "discountPercentage": "20",
+        "discountAmount": {
+          "value": "15.00",
+          "currency": "USD"
+        },
+        "priceTreatment": "LIST_PRICE"
+      },
+      "condition": "New",
+      "conditionId": "1000",
+      "thumbnailImages": [
+        {
+          "imageUrl": "https://i.ebayimg.com/images/g/n**************a/s-l***0.jpg"
+        }
+      ],
+      "shippingOptions": [
+        {
+          "shippingCostType": "FIXED",
+          "shippingCost": {
+            "value": "0.00",
+            "currency": "USD"
+          },
+          "minEstimatedDeliveryDate": "2022-11-19T08:00:00.000Z",
+          "maxEstimatedDeliveryDate": "2022-11-21T08:00:00.000Z",
+          "guaranteedDelivery": true
+        }
+      ],
+      "buyingOptions": ["FIXED_PRICE", "BEST_OFFER"],
+      "itemAffiliateWebUrl": "https://www.ebay.com/itm/1**********1?hash=i************d*9",
+      "itemWebUrl": "https://www.ebay.com/itm/1**********1?hash=i************d*p",
+      "itemLocation": {
+        "postalCode": "0****",
+        "country": "US"
+      },
+      "additionalImages": [
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_2_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_3_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_4_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_5_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_6_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_7_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_8_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_9_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_10_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_11_0_1/225x225.jpg"
+        },
+        {
+          "imageUrl": "https://origin-galleryplus.ebayimg.com/ws/web/1**********1_12_0_1/225x225.jpg"
+        }
+      ],
+      "adultOnly": false,
+      "legacyItemId": "1**********1",
+      "availableCoupons": false,
+      "itemCreationDate": "2022-12-25T07:14:44.000Z",
+      "topRatedBuyingExperience": true,
+      "priorityListing": true,
+      "listingMarketplaceId": "EBAY_US"
+    }
+  ]
+}

Script/SonarQube_Local.sh

@@ -0,0 +1,5 @@
+mvn clean verify sonar:sonar -Pcoverage \
+  -Dsonar.projectKey=EasyDrop \
+  -Dsonar.projectName='EasyDrop' \
+  -Dsonar.host.url=http://localhost:9000 \
+  -Dsonar.token=sqp_82d35689c620c15fd1064549375e17a2a5b0b931

config/demo.config.properties

@@ -1,3 +1,5 @@
 # Amazon Credentials
 AMAZON_API_URL=
-AMAZON_API_KEY=
+AMAZON_API_KEY=
+EBAY_API_URL=
+EBAY_API_KEY=

lombok.config

@@ -0,0 +1,2 @@
+config.stopBubbling = true
+lombok.addLombokGeneratedAnnotation = true

pom.xml

@@ -5,7 +5,7 @@
     <groupId>de.rwu</groupId>
     <artifactId>easydrop</artifactId>
     <packaging>jar</packaging>
-    <version>0.1.0</version>
+    <version>0.2.0-SNAPSHOT</version>
     <name>EasyDrop</name>
     <url>http://maven.apache.org</url>
 
@@ -16,16 +16,29 @@
     </properties>
 
     <dependencies>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.28</version>
+            <scope>provided</scope>
+        </dependency>
+
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
-            <version>5.8.0</version>
+            <version>5.9.3</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>
-            <version>5.8.0</version>
+            <version>5.9.3</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
+            <version>5.9.3</version>
             <scope>test</scope>
         </dependency>
 

src/main/java/de/rwu/easydrop/Main.java

@@ -5,7 +5,8 @@ import javax.naming.ConfigurationException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import de.rwu.easydrop.api.client.AmazonProductDataSource;
+import de.rwu.easydrop.api.client.DataSourceFactory;
+import de.rwu.easydrop.service.retriever.ProductRetriever;
 import de.rwu.easydrop.util.Config;
 
 /**
@@ -33,17 +34,12 @@ public final class Main {
      */
     public static void main(final String[] args) throws ConfigurationException {
         Config config = Config.getInstance();
-        config.loadConfig();
+        DataSourceFactory dataSourceFactory = new DataSourceFactory(config);
-        String amznBaseUrl = config.getProperty("AMAZON_API_URL");
+        ProductRetriever retriever = new ProductRetriever(dataSourceFactory);
-        String amznApiKey = config.getProperty("AMAZON_API_KEY");
-        String testProduct = null;
 
-        AmazonProductDataSource amznSrc = new AmazonProductDataSource(amznBaseUrl, amznApiKey);
+        String amznProduct = retriever.getProductFromAmazon("B096Y2TYKV").toString();
-        try {
+        LOGGER.info(amznProduct);
-            testProduct = amznSrc.getProductDTOById("B096Y2TYKV").toString();
+        String ebayProduct = retriever.getProductFromEbay("Gigabyte GeForce RTX 3060").toString();
-            LOGGER.info(testProduct);
+        LOGGER.info(ebayProduct);
-        } catch (IllegalArgumentException e) {
-            LOGGER.error("Something went wrong :(", e);
-        }
     }
 }

src/main/java/de/rwu/easydrop/api/client/AbstractDataSource.java

@@ -0,0 +1,100 @@
+package de.rwu.easydrop.api.client;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
+import java.net.URL;
+
+import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.exception.DataSourceException;
+import de.rwu.easydrop.util.FormattingUtil;
+
+/**
+ * Helper class for shared data and functions between data sources.
+ *
+ * @since 0.2.0
+ */
+public abstract class AbstractDataSource implements DataSource {
+
+    /**
+     * Returns the data origin for the current source.
+     *
+     * @return Data source name
+     */
+    protected abstract String getDataOrigin();
+
+    /**
+     * Returns the data source's API key.
+     *
+     * @return Data source API key
+     */
+    protected abstract String getApiKey();
+
+    /**
+     * Enriches a ProductDTO with API-gathered data.
+     *
+     * @param product Unfinished ProductDTO
+     * @param json    Product data
+     * @return Finished ProductDTO
+     */
+    protected abstract ProductDTO buildProductDTO(ProductDTO product, String json);
+
+    /**
+     * Overridable standard implementation.
+     */
+    @Override
+    public ProductDTO getProductDTOById(final String productIdentifier)
+            throws IllegalArgumentException {
+        StringBuilder response = new StringBuilder();
+        String dataOrigin = getDataOrigin();
+        String apiKey = getApiKey();
+        ProductDTO product = new ProductDTO(productIdentifier, dataOrigin);
+
+        try {
+            String urlReadyIdentifier = FormattingUtil.urlEncode(productIdentifier);
+            URL apiUrl = createApiUrl(urlReadyIdentifier);
+
+            HttpURLConnection connection = (HttpURLConnection) apiUrl.openConnection();
+            connection.setRequestMethod("GET");
+            connection.setRequestProperty("Credential", apiKey);
+
+            int responseCode = connection.getResponseCode();
+            BufferedReader reader;
+            if (responseCode == HttpURLConnection.HTTP_OK) {
+                reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
+            } else {
+                throw new DataSourceException(
+                        "Nothing found: "
+                                + dataOrigin
+                                + " API responded with error code "
+                                + responseCode);
+            }
+
+            String line;
+            while ((line = reader.readLine()) != null) {
+                response.append(line);
+            }
+            reader.close();
+
+            buildProductDTO(product, response.toString());
+        } catch (IOException e) {
+            throw new DataSourceException(
+                    "Couldn't fulfill "
+                            + dataOrigin
+                            + " API request");
+        }
+
+        return product;
+    }
+
+    /**
+     * Creates an URL object to connect to the API with.
+     *
+     * @param productIdentifier Product identifier
+     * @return URL object
+     * @throws MalformedURLException
+     */
+    protected abstract URL createApiUrl(String productIdentifier) throws MalformedURLException;
+}

src/main/java/de/rwu/easydrop/api/client/AmazonProductDataSource.java

@@ -1,9 +1,5 @@
 package de.rwu.easydrop.api.client;
 
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.io.InputStreamReader;
-import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
 import java.net.URL;
 
@@ -18,7 +14,7 @@ import de.rwu.easydrop.api.dto.ProductDTO;
  *
  * @since 0.1.0
  */
-public final class AmazonProductDataSource implements DataSource {
+public final class AmazonProductDataSource extends AbstractDataSource {
     /**
      * Name of this data source.
      */
@@ -28,7 +24,7 @@ public final class AmazonProductDataSource implements DataSource {
      */
     private String baseUrl;
     /**
-     * Credential key to authorize acccess.
+     * Credential key to authorize access.
      */
     private String apiKey;
     /**
@@ -52,48 +48,7 @@ public final class AmazonProductDataSource implements DataSource {
     }
 
     @Override
-    public ProductDTO getProductDTOById(final String productId) throws IllegalArgumentException {
+    protected ProductDTO buildProductDTO(final ProductDTO product, final String json) {
-        StringBuilder response = new StringBuilder();
-        ProductDTO product = new ProductDTO(productId, DATA_ORIGIN);
-
-        try {
-            URL apiUrl = createApiUrl(productId);
-
-            HttpURLConnection connection = (HttpURLConnection) apiUrl.openConnection();
-            connection.setRequestMethod("GET");
-            connection.setRequestProperty("Credential", apiKey);
-
-            int responseCode = connection.getResponseCode();
-            BufferedReader reader;
-            if (responseCode == HttpURLConnection.HTTP_OK) {
-                reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
-            } else {
-                throw new IllegalArgumentException(
-                        "Nothing found: Amazon API responded with error code " + responseCode);
-            }
-
-            String line;
-            while ((line = reader.readLine()) != null) {
-                response.append(line);
-            }
-            reader.close();
-
-            buildProductDTO(product, response.toString());
-        } catch (IOException e) {
-            throw new IllegalArgumentException("Couldn't fulfill Amazon API request");
-        }
-
-        return product;
-    }
-
-    /**
-     * Enriches a ProductDTO with API-gathered data.
-     *
-     * @param product Unfinished ProductDTO
-     * @param json    Product data
-     * @return Finished ProductDTO
-     */
-    public ProductDTO buildProductDTO(final ProductDTO product, final String json) {
         String root = "$.featuredOffer.";
         ReadContext ctx = JsonPath.parse(json);
 
@@ -112,8 +67,11 @@ public final class AmazonProductDataSource implements DataSource {
         return product;
     }
 
+    /**
+     * @param productId ASIN
+     */
     @Override
-    public URL createApiUrl(final String productId) throws MalformedURLException {
+    protected URL createApiUrl(final String productId) throws MalformedURLException {
         return new URL(baseUrl
                 + "/products/2020-08-26/products/"
                 + productId
@@ -122,4 +80,14 @@ public final class AmazonProductDataSource implements DataSource {
                 + "&locale="
                 + LOCALE);
     }
+
+    @Override
+    protected String getDataOrigin() {
+        return DATA_ORIGIN;
+    }
+
+    @Override
+    protected String getApiKey() {
+        return this.apiKey;
+    }
 }

src/main/java/de/rwu/easydrop/api/client/DataSource.java

@@ -1,8 +1,5 @@
 package de.rwu.easydrop.api.client;
 
-import java.net.MalformedURLException;
-import java.net.URL;
-
 import de.rwu.easydrop.api.dto.ProductDTO;
 
 /**
@@ -12,17 +9,8 @@ public interface DataSource {
     /**
      * Retrieves product info from the data source.
      *
-     * @param productId ASIN
+     * @param productIdentifier Product identifier
      * @return ProductDTO
      */
-    ProductDTO getProductDTOById(String productId);
+    ProductDTO getProductDTOById(String productIdentifier);
-
-    /**
-     * Creates an URL object to connect to the API with.
-     *
-     * @param productId ASIN
-     * @return URL object
-     * @throws MalformedURLException
-     */
-    URL createApiUrl(String productId) throws MalformedURLException;
 }

src/main/java/de/rwu/easydrop/api/client/DataSourceFactory.java

@@ -0,0 +1,55 @@
+package de.rwu.easydrop.api.client;
+
+import javax.naming.ConfigurationException;
+
+import de.rwu.easydrop.util.Config;
+
+/**
+ * Factory for Data Sources.
+ *
+ * @since 0.2.0
+ */
+public class DataSourceFactory {
+
+    /**
+     * The data source config.
+     */
+    private Config config;
+
+    /**
+     * @param newConfig the config to set
+     */
+    public void setConfig(final Config newConfig) throws ConfigurationException {
+        this.config = newConfig;
+        this.config.loadConfig();
+    }
+
+    /**
+     * @param newConfig
+     */
+    public DataSourceFactory(final Config newConfig) throws ConfigurationException {
+        this.setConfig(newConfig);
+    }
+
+    /**
+     * Creates an Amazon Product Data Source.
+     *
+     * @return AmazonProductDataSource
+     */
+    public AmazonProductDataSource createAmazonProductDataSource() {
+        String apiUrl = config.getProperty("AMAZON_API_URL");
+        String apiKey = config.getProperty("AMAZON_API_KEY");
+        return new AmazonProductDataSource(apiUrl, apiKey);
+    }
+
+    /**
+     * Creates an eBay Item Data Source.
+     *
+     * @return EbayItemDataSource
+     */
+    public EbayItemDataSource createEbayItemDataSource() {
+        String apiUrl = config.getProperty("EBAY_API_URL");
+        String apiKey = config.getProperty("EBAY_API_KEY");
+        return new EbayItemDataSource(apiUrl, apiKey);
+    }
+}

src/main/java/de/rwu/easydrop/api/client/EbayItemDataSource.java

@@ -0,0 +1,88 @@
+package de.rwu.easydrop.api.client;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+
+import com.jayway.jsonpath.JsonPath;
+import com.jayway.jsonpath.PathNotFoundException;
+import com.jayway.jsonpath.ReadContext;
+
+import de.rwu.easydrop.api.dto.ProductDTO;
+
+/**
+ * Interface to an eBay data source.
+ *
+ * @since 0.2.0
+ */
+public final class EbayItemDataSource extends AbstractDataSource {
+    /**
+     * Name of this data source.
+     */
+    private static final String DATA_ORIGIN = "eBay";
+    /**
+     * Base URL to the eBay data source.
+     */
+    private String baseUrl;
+    /**
+     * Credential key to authorize access.
+     */
+    private String apiKey;
+
+    /**
+     * Sets up instance with Base URL and API Key.
+     *
+     * @param newBaseUrl
+     * @param newApiKey
+     */
+    public EbayItemDataSource(final String newBaseUrl, final String newApiKey) {
+        this.baseUrl = newBaseUrl;
+        this.apiKey = newApiKey;
+    }
+
+    /**
+     * @param searchQuery Exact product name or other valid identifier.
+     */
+    @Override
+    protected URL createApiUrl(final String searchQuery) throws MalformedURLException {
+        return new URL(baseUrl
+                + "/buy/browse/v1/item_summary/search?q="
+                + searchQuery
+                + "&limit=1&offset=0");
+    }
+
+    /**
+     * Enriches a ProductDTO with API-gathered data.
+     *
+     * @param product Unfinished ProductDTO
+     * @param json    Product data
+     * @return Finished ProductDTO
+     */
+    protected ProductDTO buildProductDTO(final ProductDTO product, final String json) {
+        String root = "$.itemSummaries[0].";
+        ReadContext ctx = JsonPath.parse(json);
+
+        try {
+            product.setDataOrigin(DATA_ORIGIN);
+            product.setAvailable(
+                    ctx.read(root + "shippingOptions[0].guaranteedDelivery", boolean.class));
+            product.setCurrentPrice(ctx.read(root + "price.value", double.class));
+            product.setDeliveryPrice(
+                    ctx.read(root + "shippingOptions[0].shippingCost.value", double.class));
+            product.setMerchant(ctx.read(root + "seller.username", String.class));
+        } catch (PathNotFoundException e) {
+            // Pass, allow incomplete ProductDTO to pass for later validation
+        }
+
+        return product;
+    }
+
+    @Override
+    protected String getDataOrigin() {
+        return DATA_ORIGIN;
+    }
+
+    @Override
+    protected String getApiKey() {
+        return this.apiKey;
+    }
+}

src/main/java/de/rwu/easydrop/api/dto/ProductDTO.java

@@ -1,139 +1,52 @@
 package de.rwu.easydrop.api.dto;
 
-import de.rwu.easydrop.util.FormattingUtil;
+import lombok.Data;
 
 /**
  * Product data transfer object.
  *
  * @since 0.1.0
  */
+@Data
 public class ProductDTO {
     /**
      * Data source platform, like "Amazon".
      */
     private String dataOrigin;
 
-    /**
-     * @return the dataOrigin
-     */
-    public String getDataOrigin() {
-        return dataOrigin;
-    }
-
-    /**
-     * @param newDataOrigin the dataOrigin to set
-     */
-    public void setDataOrigin(final String newDataOrigin) {
-        this.dataOrigin = newDataOrigin;
-    }
-
     /**
      * Platform internal product identifier.
      */
     private String productId;
 
-    /**
-     * @return the productId
-     */
-    public String getProductId() {
-        return productId;
-    }
-
     /**
      * Current product price per piece in Euro.
      */
     private double currentPrice;
 
-    /**
-     * @return the currentPrice
-     */
-    public double getCurrentPrice() {
-        return currentPrice;
-    }
-
-    /**
-     * @param newCurrentPrice the currentPrice to set
-     */
-    public void setCurrentPrice(final double newCurrentPrice) {
-        this.currentPrice = newCurrentPrice;
-    }
-
     /**
      * Name of mercant offering the product on the platform.
      */
     private String merchant;
 
-    /**
-     * @return the merchant
-     */
-    public String getMerchant() {
-        return merchant;
-    }
-
-    /**
-     * @param newMerchant the merchant to set
-     */
-    public void setMerchant(final String newMerchant) {
-        this.merchant = newMerchant;
-    }
-
     /**
      * Additional Cost for delivery in Euro.
      */
     private double deliveryPrice;
 
-    /**
-     * @return the deliveryPrice
-     */
-    public double getDeliveryPrice() {
-        return deliveryPrice;
-    }
-
-    /**
-     * @param newDeliveryPrice the deliveryPrice to set
-     */
-    public void setDeliveryPrice(final double newDeliveryPrice) {
-        this.deliveryPrice = newDeliveryPrice;
-    }
-
     /**
      * Whether the product can be purchased at this point.
      */
     private boolean available;
 
-    /**
-     * @return the available
-     */
-    public boolean isAvailable() {
-        return available;
-    }
-
-    /**
-     * @param newAvailable the available to set
-     */
-    public void setAvailable(final boolean newAvailable) {
-        this.available = newAvailable;
-    }
-
     /**
      * Creates ProductDTO instance.
      *
-     * @param newProductId  Interal Product indetifier
+     * @param newProductId  Internal Product indetifier
      * @param newDataOrigin Data Origin
      */
     public ProductDTO(final String newProductId, final String newDataOrigin) {
         this.productId = newProductId;
         this.dataOrigin = newDataOrigin;
     }
-
-    @Override
-    public final String toString() {
-        return "ProductDTO{"
-                + productId + " from "
-                + merchant + " ("
-                + dataOrigin + ")"
-                + " at "
-                + FormattingUtil.formatEuro(currentPrice) + " (available: "
-                + (available ? "yes" : "no") + ")}";
-    }
 }

src/main/java/de/rwu/easydrop/data/model/Product.java

@@ -1,10 +0,0 @@
-package de.rwu.easydrop.data.model;
-
-/**
- * A Product.
- *
- * TODO implement
- */
-public class Product {
-
-}

src/main/java/de/rwu/easydrop/data/model/package-info.java

@@ -1,6 +0,0 @@
-/**
- * Business objects.
- *
- * TODO implement
- */
-package de.rwu.easydrop.data.model;

src/main/java/de/rwu/easydrop/exception/DataSourceException.java

@@ -0,0 +1,27 @@
+package de.rwu.easydrop.exception;
+
+/**
+ * Exception that signifies the data of a Product are invalid.
+ *
+ * @since 0.2.0
+ */
+public class DataSourceException extends RuntimeException {
+    /**
+     * Throws an exception that signifies the data of a Product are invalid.
+     *
+     * @param message
+     */
+    public DataSourceException(final String message) {
+        super(message);
+    }
+
+    /**
+     * Throws an exception that signifies the data of a Product are invalid.
+     *
+     * @param message
+     * @param cause
+     */
+    public DataSourceException(final String message, final Throwable cause) {
+        super(message, cause);
+    }
+}

src/main/java/de/rwu/easydrop/exception/InvalidProductException.java

@@ -0,0 +1,27 @@
+package de.rwu.easydrop.exception;
+
+/**
+ * Exception that signifies the data of a Product are invalid.
+ *
+ * @since 0.2.0
+ */
+public class InvalidProductException extends RuntimeException {
+    /**
+     * Throws an exception that signifies the data of a Product are invalid.
+     *
+     * @param message
+     */
+    public InvalidProductException(final String message) {
+        super(message);
+    }
+
+    /**
+     * Throws an exception that signifies the data of a Product are invalid.
+     *
+     * @param message
+     * @param cause
+     */
+    public InvalidProductException(final String message, final Throwable cause) {
+        super(message, cause);
+    }
+}

src/main/java/de/rwu/easydrop/exception/package-info.java

@@ -0,0 +1,6 @@
+/**
+ * Contains EasyDrop-related custom exceptions.
+ *
+ * @since 0.2.0
+ */
+package de.rwu.easydrop.exception;

src/main/java/de/rwu/easydrop/model/Product.java

@@ -0,0 +1,53 @@
+package de.rwu.easydrop.model;
+
+import de.rwu.easydrop.util.FormattingUtil;
+import lombok.Data;
+
+/**
+ * A Product.
+ *
+ * @since 0.2.0
+ */
+@Data
+public class Product {
+    /**
+     * Data source platform, like "Amazon".
+     */
+    private String dataOrigin;
+
+    /**
+     * Platform internal product identifier.
+     */
+    private String productId;
+
+    /**
+     * Current product price per piece in Euro.
+     */
+    private double currentPrice;
+
+    /**
+     * Name of mercant offering the product on the platform.
+     */
+    private String merchant;
+
+    /**
+     * Additional Cost for delivery in Euro.
+     */
+    private double deliveryPrice;
+
+    /**
+     * Whether the product can be purchased at this point.
+     */
+    private boolean available;
+
+    @Override
+    public final String toString() {
+        return "Product: ["
+                + productId + " from "
+                + merchant + " ("
+                + dataOrigin + ")"
+                + " at "
+                + FormattingUtil.formatEuro(currentPrice) + " (available: "
+                + (available ? "yes" : "no") + ")]";
+    }
+}

src/main/java/de/rwu/easydrop/model/package-info.java

@@ -0,0 +1,6 @@
+/**
+ * Business objects.
+ *
+ * @since 0.2.0
+ */
+package de.rwu.easydrop.model;

src/main/java/de/rwu/easydrop/service/mapping/ProductMapper.java

@@ -1,14 +1,44 @@
 package de.rwu.easydrop.service.mapping;
 
+import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.model.Product;
+
 /**
  * Maps between Product, ProductDAO and ProductDTO.
  *
- * TODO implement
+ * @since 0.2.0
  *
  * @see Product
  * @see ProductDTO
  * @see ProductDAO
  */
-public class ProductMapper {
+public final class ProductMapper {
 
+    /**
+     * Private constructor to prevent unwanted instantiation.
+     *
+     * @throws UnsupportedOperationException always
+     */
+    private ProductMapper() throws UnsupportedOperationException {
+        throw new UnsupportedOperationException("This is a mapping class, don't instantiate it.");
+    }
+
+    /**
+     * Creates a Product object from a corresponding DTO.
+     *
+     * @param dto Product Data Transfer Object
+     * @return Product
+     */
+    public static Product mapProductFromDTO(final ProductDTO dto) {
+        Product product = new Product();
+
+        product.setAvailable(dto.isAvailable());
+        product.setCurrentPrice(dto.getCurrentPrice());
+        product.setDataOrigin(dto.getDataOrigin());
+        product.setDeliveryPrice(dto.getDeliveryPrice());
+        product.setMerchant(dto.getMerchant());
+        product.setProductId(dto.getProductId());
+
+        return product;
+    }
 }

src/main/java/de/rwu/easydrop/service/mapping/package-info.java

@@ -1,6 +1,6 @@
 /**
  * Maps different formats of corresponding objects.
  *
- * TODO implement
+ * @since 0.2.0
  */
 package de.rwu.easydrop.service.mapping;

src/main/java/de/rwu/easydrop/service/retriever/ProductRetriever.java

@@ -0,0 +1,67 @@
+package de.rwu.easydrop.service.retriever;
+
+import de.rwu.easydrop.api.client.AmazonProductDataSource;
+import de.rwu.easydrop.api.client.DataSourceFactory;
+import de.rwu.easydrop.api.client.EbayItemDataSource;
+import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.model.Product;
+import de.rwu.easydrop.service.mapping.ProductMapper;
+import de.rwu.easydrop.service.validation.ProductValidator;
+
+/**
+ * Retrieves Product Objects from various data sources.
+ *
+ * @since 0.2.0
+ */
+public class ProductRetriever {
+    /**
+     * Data source factory.
+     */
+    private DataSourceFactory dataSourceFactory;
+
+    /**
+     * @param newDataSourceFactory the dataSourceFactory to set
+     */
+    public void setDataSourceFactory(final DataSourceFactory newDataSourceFactory) {
+        this.dataSourceFactory = newDataSourceFactory;
+    }
+
+    /**
+     * @param newDataSourceFactory
+     */
+    public ProductRetriever(final DataSourceFactory newDataSourceFactory) {
+        this.setDataSourceFactory(newDataSourceFactory);
+    }
+
+    /**
+     * Retrieves a product from Amazon.
+     *
+     * @param asin Product identifier
+     * @return Product from Amazon
+     */
+    public Product getProductFromAmazon(final String asin) {
+        AmazonProductDataSource dataSource = dataSourceFactory.createAmazonProductDataSource();
+        ProductDTO dto = dataSource.getProductDTOById(asin);
+
+        Product product = ProductMapper.mapProductFromDTO(dto);
+        ProductValidator.validate(product);
+
+        return product;
+    }
+
+    /**
+     * Retrieves a product from eBay.
+     *
+     * @param query Product search query
+     * @return Product from eBay
+     */
+    public Product getProductFromEbay(final String query) {
+        EbayItemDataSource dataSource = dataSourceFactory.createEbayItemDataSource();
+        ProductDTO dto = dataSource.getProductDTOById(query);
+
+        Product product = ProductMapper.mapProductFromDTO(dto);
+        ProductValidator.validate(product);
+
+        return product;
+    }
+}

src/main/java/de/rwu/easydrop/service/retriever/package-info.java

@@ -0,0 +1,6 @@
+/**
+ * Retrieves Objects from a data source.
+ *
+ * @since 0.2.0
+ */
+package de.rwu.easydrop.service.retriever;

src/main/java/de/rwu/easydrop/service/validation/ProductValidator.java

@@ -1,10 +1,56 @@
 package de.rwu.easydrop.service.validation;
 
+import java.util.HashSet;
+import java.util.Set;
+
+import de.rwu.easydrop.exception.InvalidProductException;
+import de.rwu.easydrop.model.Product;
+
 /**
  * Confirms validity of Product data.
  *
- * @since 0.1.0
+ * @since 0.2.0
  */
-public class ProductValidator {
+public final class ProductValidator {
 
+    /**
+     * Private constructor to prevent unwanted instantiation.
+     *
+     * @throws UnsupportedOperationException always
+     */
+    private ProductValidator() throws UnsupportedOperationException {
+        throw new UnsupportedOperationException("This is a validator class, don't instantiate it.");
+    }
+
+    /**
+     * Makes sure a Product does not contain invalid information.
+     *
+     * @param product the Product
+     */
+    public static void validate(final Product product) {
+        if (product.getCurrentPrice() == 0.00) {
+            throw new InvalidProductException("Current price cannot be 0.00");
+        }
+        if (!isInValidDataOrigins(product.getDataOrigin())) {
+            throw new InvalidProductException("Unknown data source");
+        }
+        if (product.getProductId().equals("")) {
+            throw new InvalidProductException("Product ID cannot be empty");
+        }
+    }
+
+    /**
+     * Checks whether a dataOrigin is within the set of valid ones.
+     *
+     * @param dataOrigin like "Amazon"
+     * @return true if valid
+     */
+    public static boolean isInValidDataOrigins(final String dataOrigin) {
+        Set<String> validOrigins = new HashSet<>();
+
+        validOrigins.add("Amazon");
+        validOrigins.add("eBay");
+
+        return validOrigins.contains(dataOrigin);
+    }
 }

src/main/java/de/rwu/easydrop/service/validation/package-info.java

@@ -1,6 +1,6 @@
 /**
  * Supports validation processes.
  *
- * TODO implement
+ * @since 0.2.0
  */
 package de.rwu.easydrop.service.validation;

src/main/java/de/rwu/easydrop/util/Config.java

@@ -56,7 +56,7 @@ public final class Config {
      */
     public static Config getInstance() {
         if (instance == null) {
-            return new Config();
+            instance = new Config();
         }
 
         return instance;
@@ -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;
+    }
 }

src/main/java/de/rwu/easydrop/util/FormattingUtil.java

@@ -27,4 +27,14 @@ public final class FormattingUtil {
     public static String formatEuro(final double amount) {
         return String.format(Locale.GERMAN, "%,.2f", amount) + " €";
     }
+
+    /**
+     * Makes a string URL ready. For now, only spaces are replaced.
+     *
+     * @param str
+     * @return URL-ready string
+     */
+    public static String urlEncode(final String str) {
+        return str.replace(" ", "+");
+    }
 }

src/main/resources/logback.xml

@@ -1,4 +1,6 @@
 <configuration>
+    <logger name="com.jayway.jsonpath" level="OFF" />
+
     <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
         <encoder>
             <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
@@ -6,7 +8,7 @@
         </encoder>
     </appender>
 
-    <root level="info">
+    <root level="INFO">
         <appender-ref ref="STDOUT" />
     </root>
 </configuration>

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

@@ -20,6 +20,7 @@ import org.junit.jupiter.api.Test;
 import org.mockito.MockitoAnnotations;
 
 import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.exception.DataSourceException;
 
 class AmazonProductDataSourceTest {
 
@@ -150,6 +151,7 @@ class AmazonProductDataSourceTest {
 
         AmazonProductDataSource dataSource = mock(AmazonProductDataSource.class);
         URL mockURL = mock(URL.class);
+        when(dataSource.getDataOrigin()).thenReturn(demoDataOrigin);
         when(dataSource.createApiUrl(demoProductId)).thenReturn(mockURL);
         when(dataSource.getProductDTOById(demoProductId)).thenCallRealMethod();
         HttpURLConnection mockConnection = mock(HttpURLConnection.class);
@@ -157,7 +159,7 @@ class AmazonProductDataSourceTest {
         when(mockConnection.getResponseCode()).thenReturn(HttpURLConnection.HTTP_NOT_FOUND);
 
         // Invoke the method and verify the exception
-        IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> {
+        DataSourceException exception = assertThrows(DataSourceException.class, () -> {
             dataSource.getProductDTOById(demoProductId);
         });
 
@@ -170,6 +172,7 @@ class AmazonProductDataSourceTest {
         // Set up the test environment
         AmazonProductDataSource dataSource = mock(AmazonProductDataSource.class);
         URL mockURL = mock(URL.class);
+        when(dataSource.getDataOrigin()).thenReturn(demoDataOrigin);
         when(dataSource.createApiUrl(demoProductId)).thenReturn(mockURL);
         when(dataSource.getProductDTOById(demoProductId)).thenCallRealMethod();
         when(dataSource.buildProductDTO(any(), anyString())).thenCallRealMethod();
@@ -179,11 +182,23 @@ class AmazonProductDataSourceTest {
         when(mockConnection.getInputStream()).thenThrow(new IOException());
 
         // Invoke the method and verify the exception
-        IllegalArgumentException exception = assertThrows(IllegalArgumentException.class, () -> {
+        DataSourceException exception = assertThrows(DataSourceException.class, () -> {
             dataSource.getProductDTOById(demoProductId);
         });
 
         // Verify the exception message
         assertEquals("Couldn't fulfill Amazon API request", exception.getMessage());
     }
+
+    @Test
+    void getDataOrigin_ReturnsExpectedDataOrigin() {
+        String dataOrigin = demoDataSource.getDataOrigin();
+        assertEquals(demoDataOrigin, dataOrigin);
+    }
+
+    @Test
+    void getApiKey_ReturnsExpectedApiKey() {
+        String apiKey = demoDataSource.getApiKey();
+        assertEquals(demoApiKey, apiKey);
+    }
 }

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

@@ -0,0 +1,48 @@
+package de.rwu.easydrop.api.client;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.when;
+
+import javax.naming.ConfigurationException;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import de.rwu.easydrop.util.Config;
+
+class DataSourceFactoryTest {
+    @Mock
+    private Config config;
+
+    private DataSourceFactory dataSourceFactory;
+
+    @BeforeEach
+    void setUp() throws ConfigurationException {
+        MockitoAnnotations.openMocks(this);
+        when(config.getProperty("AMAZON_API_URL")).thenReturn("https://api.amazon.com");
+        when(config.getProperty("AMAZON_API_KEY")).thenReturn("amazon-api-key");
+        when(config.getProperty("EBAY_API_URL")).thenReturn("https://api.ebay.com");
+        when(config.getProperty("EBAY_API_KEY")).thenReturn("ebay-api-key");
+        dataSourceFactory = new DataSourceFactory(config);
+    }
+
+    @Test
+    void createAmazonProductDataSource_ReturnsAmazonProductDataSource() {
+        // Act
+        AmazonProductDataSource dataSource = dataSourceFactory.createAmazonProductDataSource();
+
+        // Assert
+        assertEquals("amazon-api-key", dataSource.getApiKey());
+    }
+
+    @Test
+    void createEbayItemDataSource_ReturnsEbayItemDataSource() {
+        // Act
+        EbayItemDataSource dataSource = dataSourceFactory.createEbayItemDataSource();
+
+        // Assert
+        assertEquals("ebay-api-key", dataSource.getApiKey());
+    }
+}

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

@@ -0,0 +1,125 @@
+package de.rwu.easydrop.api.client;
+
+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.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
+import java.net.URL;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.MockitoAnnotations;
+
+import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.exception.DataSourceException;
+
+class EbayItemDataSourceTest {
+    private EbayItemDataSource demoDataSource;
+
+    private static String demoApiKey = "my-api-key";
+    private static String demoApiUrl = "https://www.example.com/api";
+    private static String demoDataOrigin = "eBay";
+    private static String demoQuery = "iPhone";
+
+    @BeforeEach
+    void setUp() {
+        demoDataSource = new EbayItemDataSource(demoApiUrl, demoApiKey);
+        MockitoAnnotations.openMocks(this);
+    }
+
+    @Test
+    void testConstructor() {
+        // Assert
+        try {
+            Field baseUrlField = EbayItemDataSource.class.getDeclaredField("baseUrl");
+            baseUrlField.setAccessible(true);
+            Assertions.assertEquals(demoApiUrl, baseUrlField.get(demoDataSource));
+
+            Field apiKeyField = EbayItemDataSource.class.getDeclaredField("apiKey");
+            apiKeyField.setAccessible(true);
+            Assertions.assertEquals(demoApiKey, apiKeyField.get(demoDataSource));
+        } catch (NoSuchFieldException e) {
+            Assertions.fail();
+        } catch (IllegalAccessException e) {
+            Assertions.fail();
+        }
+    }
+
+    @Test
+    void createApiUrl_ValidSearchQuery_ReturnsValidUrl() throws MalformedURLException {
+        URL apiUrl = demoDataSource.createApiUrl(demoQuery);
+
+        assertNotNull(apiUrl);
+        assertEquals("https://www.example.com/api/buy/browse/v1/item_summary/search?q=iPhone&limit=1&offset=0",
+                apiUrl.toString());
+    }
+
+    @Test
+    void buildProductDTO_ValidJson_ReturnsValidProductDTO() {
+        ProductDTO product = new ProductDTO(demoQuery, demoDataOrigin);
+        String json = "{\"itemSummaries\":[{\"shippingOptions\":[{\"guaranteedDelivery\":true,\"shippingCost\":{\"value\":10}}],\"price\":{\"value\":999.99},\"seller\":{\"username\":\"seller123\"}}]}";
+
+        ProductDTO result = demoDataSource.buildProductDTO(product, json);
+
+        assertEquals(demoDataOrigin, result.getDataOrigin());
+        assertEquals(true, result.isAvailable());
+        assertEquals(999.99, result.getCurrentPrice());
+        assertEquals(10.0, result.getDeliveryPrice());
+        assertEquals("seller123", result.getMerchant());
+    }
+
+    @Test
+    void buildProductDTO_InvalidJson_ReturnsProductDTOWithDefaults() {
+        ProductDTO product = new ProductDTO(demoQuery, demoDataOrigin);
+        String json = "{\"itemSummaries\":[]}"; // Empty JSON to simulate missing data
+
+        ProductDTO result = demoDataSource.buildProductDTO(product, json);
+
+        assertEquals("eBay", result.getDataOrigin());
+        assertEquals(false, result.isAvailable()); // Default value for boolean
+        assertEquals(0.0, result.getCurrentPrice()); // Default value for double
+        assertEquals(0.0, result.getDeliveryPrice()); // Default value for double
+        assertEquals(null, result.getMerchant()); // Default value for String
+    }
+
+    @Test
+    void getDataOrigin_ReturnsExpectedDataOrigin() {
+        String dataOrigin = demoDataSource.getDataOrigin();
+        assertEquals(demoDataOrigin, dataOrigin);
+    }
+
+    @Test
+    void getApiKey_ReturnsExpectedApiKey() {
+        String apiKey = demoDataSource.getApiKey();
+        assertEquals(demoApiKey, apiKey);
+    }
+
+    @Test
+    void testGetProductDTOById_failedRequest() throws IOException {
+        // Set up the test environment
+
+        EbayItemDataSource dataSource = mock(EbayItemDataSource.class);
+        URL mockURL = mock(URL.class);
+        when(dataSource.getDataOrigin()).thenReturn(demoDataOrigin);
+        when(dataSource.createApiUrl(demoQuery)).thenReturn(mockURL);
+        when(dataSource.getProductDTOById(demoQuery)).thenCallRealMethod();
+        HttpURLConnection mockConnection = mock(HttpURLConnection.class);
+        when(mockURL.openConnection()).thenReturn(mockConnection);
+        when(mockConnection.getResponseCode()).thenReturn(HttpURLConnection.HTTP_NOT_FOUND);
+
+        // Invoke the method and verify the exception
+        DataSourceException exception = assertThrows(DataSourceException.class, () -> {
+            dataSource.getProductDTOById(demoQuery);
+        });
+
+        // Verify the exception message
+        assertEquals("Nothing found: eBay API responded with error code 404", exception.getMessage());
+    }
+}

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() {
+    void constructor_SetsProductIdAndDataOrigin() {
-        ProductDTO product1 = new ProductDTO("12345", "Amazon");
+        // Arrange
-        product1.setMerchant("Merchant A");
+        String productId = "12345";
-        product1.setCurrentPrice(19.99);
+        String dataOrigin = "Amazon";
-        product1.setAvailable(true);
 
-        String expectedString1 = "ProductDTO{12345 from Merchant A (Amazon) at 19,99 € (available: yes)}";
+        // Act
-        String result1 = product1.toString();
+        ProductDTO productDTO = new ProductDTO(productId, dataOrigin);
 
-        assertEquals(expectedString1, result1);
+        // Assert
+        assertEquals(productId, productDTO.getProductId());
+        assertEquals(dataOrigin, productDTO.getDataOrigin());
     }
 
     @Test
-    void testToString2() {
+    void gettersAndSetters_WorkAsExpected() {
-        ProductDTO product2 = new ProductDTO("67890", "eBay");
+        // Arrange
-        product2.setMerchant("Merchant B");
+        ProductDTO productDTO = new ProductDTO("12345", "Amazon");
-        product2.setCurrentPrice(9.99);
-        product2.setAvailable(false);
 
-        String expectedString2 = "ProductDTO{67890 from Merchant B (eBay) at 9,99 € (available: no)}";
+        // Act and Assert
-        String result2 = product2.toString();
+        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());
     }
 }

src/test/java/de/rwu/easydrop/exception/DataSourceExceptionTest.java

@@ -0,0 +1,61 @@
+package de.rwu.easydrop.exception;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class DataSourceExceptionTest {
+
+    @Test
+    void constructor_WithMessage_SetsMessage() {
+        // Arrange
+        String message = "Data source error";
+
+        // Act
+        DataSourceException exception = new DataSourceException(message);
+
+        // Assert
+        assertEquals(message, exception.getMessage());
+    }
+
+    @Test
+    void constructor_WithMessageAndCause_SetsMessageAndCause() {
+        // Arrange
+        String message = "Data source error";
+        Throwable cause = new IllegalArgumentException("Invalid argument");
+
+        // Act
+        DataSourceException exception = new DataSourceException(message, cause);
+
+        // Assert
+        assertEquals(message, exception.getMessage());
+        assertEquals(cause, exception.getCause());
+    }
+
+    @Test
+    void constructor_WithNullMessage_SetsNullMessage() {
+        // Act
+        DataSourceException exception = new DataSourceException(null);
+
+        // Assert
+        assertEquals(null, exception.getMessage());
+    }
+
+    @Test
+    void constructor_WithNullCause_SetsNullCause() {
+        // Act
+        DataSourceException exception = new DataSourceException("Data source error", null);
+
+        // Assert
+        assertEquals(null, exception.getCause());
+    }
+
+    @Test
+    void throw_DataSourceException() {
+        // Act and Assert
+        assertThrows(DataSourceException.class, () -> {
+            throw new DataSourceException("Data source error");
+        });
+    }
+}

src/test/java/de/rwu/easydrop/exception/InvalidProductExceptionTest.java

@@ -0,0 +1,61 @@
+package de.rwu.easydrop.exception;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class InvalidProductExceptionTest {
+
+    @Test
+    void constructor_WithMessage_SetsMessage() {
+        // Arrange
+        String message = "Invalid product data";
+
+        // Act
+        InvalidProductException exception = new InvalidProductException(message);
+
+        // Assert
+        assertEquals(message, exception.getMessage());
+    }
+
+    @Test
+    void constructor_WithMessageAndCause_SetsMessageAndCause() {
+        // Arrange
+        String message = "Invalid product data";
+        Throwable cause = new IllegalArgumentException("Invalid argument");
+
+        // Act
+        InvalidProductException exception = new InvalidProductException(message, cause);
+
+        // Assert
+        assertEquals(message, exception.getMessage());
+        assertEquals(cause, exception.getCause());
+    }
+
+    @Test
+    void constructor_WithNullMessage_SetsNullMessage() {
+        // Act
+        InvalidProductException exception = new InvalidProductException(null);
+
+        // Assert
+        assertEquals(null, exception.getMessage());
+    }
+
+    @Test
+    void constructor_WithNullCause_SetsNullCause() {
+        // Act
+        InvalidProductException exception = new InvalidProductException("Invalid product data", null);
+
+        // Assert
+        assertEquals(null, exception.getCause());
+    }
+
+    @Test
+    void throw_InvalidProductException() {
+        // Act and Assert
+        assertThrows(InvalidProductException.class, () -> {
+            throw new InvalidProductException("Invalid product data");
+        });
+    }
+}

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());
+    }
+}

src/test/java/de/rwu/easydrop/service/mapping/ProductMapperTest.java

@@ -0,0 +1,56 @@
+package de.rwu.easydrop.service.mapping;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Modifier;
+
+import org.junit.jupiter.api.Test;
+
+import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.model.Product;
+
+class ProductMapperTest {
+    @Test
+    void testConstructorIsPrivate()
+            throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
+        // Check for private constructor
+        Constructor<ProductMapper> constructor = ProductMapper.class.getDeclaredConstructor();
+        assertTrue(Modifier.isPrivate(constructor.getModifiers()));
+
+        // Make sure exception is thrown when instantiating
+        constructor.setAccessible(true);
+        assertThrows(InvocationTargetException.class, () -> {
+            constructor.newInstance();
+        });
+    }
+
+    @Test
+    void mapProductFromDTO_ReturnsProductWithMappedFields() {
+        // Arrange
+        ProductDTO dto = createProductDTO();
+
+        // Act
+        Product product = ProductMapper.mapProductFromDTO(dto);
+
+        // Assert
+        assertEquals(dto.isAvailable(), product.isAvailable());
+        assertEquals(dto.getCurrentPrice(), product.getCurrentPrice());
+        assertEquals(dto.getDataOrigin(), product.getDataOrigin());
+        assertEquals(dto.getDeliveryPrice(), product.getDeliveryPrice());
+        assertEquals(dto.getMerchant(), product.getMerchant());
+        assertEquals(dto.getProductId(), product.getProductId());
+    }
+
+    private ProductDTO createProductDTO() {
+        ProductDTO dto = new ProductDTO("12345", "Amazon");
+        dto.setAvailable(true);
+        dto.setCurrentPrice(9.99);
+        dto.setDeliveryPrice(2.50);
+        dto.setMerchant("Example Merchant");
+        return dto;
+    }
+}

src/test/java/de/rwu/easydrop/service/retriever/ProductRetrieverTest.java

@@ -0,0 +1,87 @@
+package de.rwu.easydrop.service.retriever;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import javax.naming.ConfigurationException;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import de.rwu.easydrop.api.client.AmazonProductDataSource;
+import de.rwu.easydrop.api.client.DataSourceFactory;
+import de.rwu.easydrop.api.client.EbayItemDataSource;
+import de.rwu.easydrop.api.dto.ProductDTO;
+import de.rwu.easydrop.model.Product;
+import de.rwu.easydrop.util.Config;
+
+class ProductRetrieverTest {
+    @Mock
+    private Config config;
+    @Mock
+    private DataSourceFactory dataSourceFactory;
+    @Mock
+    private AmazonProductDataSource amazonDataSource;
+    @Mock
+    private EbayItemDataSource ebayDataSource;
+    @Mock
+    private ProductDTO productDTO;
+    @Mock
+    private Product product;
+
+    private ProductRetriever productRetriever;
+
+    @BeforeEach
+    void setUp() throws ConfigurationException {
+        MockitoAnnotations.openMocks(this);
+        when(config.getProperty("AMAZON_API_URL")).thenReturn("https://api.amazon.com");
+        when(config.getProperty("AMAZON_API_KEY")).thenReturn("amazon-api-key");
+        dataSourceFactory.setConfig(config);
+        productRetriever = new ProductRetriever(dataSourceFactory);
+    }
+
+    @Test
+    void getProductFromAmazon_ReturnsProduct() {
+        // Arrange
+        String asin = "B01234ABC";
+        when(dataSourceFactory.createAmazonProductDataSource()).thenReturn(amazonDataSource);
+        when(amazonDataSource.getProductDTOById(asin)).thenReturn(productDTO);
+        when(productDTO.getProductId()).thenReturn(asin);
+        when(productDTO.getCurrentPrice()).thenReturn(9.99);
+        when(productDTO.getDataOrigin()).thenReturn("Amazon");
+
+        // Act
+        Product result = productRetriever.getProductFromAmazon(asin);
+
+        // Assert
+        assertNotNull(result);
+        assertEquals(asin, result.getProductId());
+        assertEquals(9.99, result.getCurrentPrice());
+        verify(amazonDataSource, times(1)).getProductDTOById(asin);
+    }
+
+    @Test
+    void getProductFromEbay_ReturnsProduct() {
+        // Arrange
+        String productQuery = "MySearchQuery";
+        when(dataSourceFactory.createEbayItemDataSource()).thenReturn(ebayDataSource);
+        when(ebayDataSource.getProductDTOById(productQuery)).thenReturn(productDTO);
+        when(productDTO.getProductId()).thenReturn(productQuery);
+        when(productDTO.getCurrentPrice()).thenReturn(9.99);
+        when(productDTO.getDataOrigin()).thenReturn("eBay");
+
+        // Act
+        Product result = productRetriever.getProductFromEbay(productQuery);
+
+        // Assert
+        assertNotNull(result);
+        assertEquals(productQuery, result.getProductId());
+        assertEquals(9.99, result.getCurrentPrice());
+        verify(ebayDataSource, times(1)).getProductDTOById(productQuery);
+    }
+}

src/test/java/de/rwu/easydrop/service/validation/ProductValidatorTest.java

@@ -0,0 +1,109 @@
+package de.rwu.easydrop.service.validation;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Modifier;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import de.rwu.easydrop.exception.InvalidProductException;
+import de.rwu.easydrop.model.Product;
+
+class ProductValidatorTest {
+
+    @Test
+    void testConstructorIsPrivate()
+            throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
+        // Check for private constructor
+        Constructor<ProductValidator> constructor = ProductValidator.class.getDeclaredConstructor();
+        assertTrue(Modifier.isPrivate(constructor.getModifiers()));
+
+        // Make sure exception is thrown when instantiating
+        constructor.setAccessible(true);
+        assertThrows(InvocationTargetException.class, () -> {
+            constructor.newInstance();
+        });
+    }
+
+    @Test
+    void validate_ValidProduct_NoExceptionThrown() {
+        // Arrange
+        Product product = new Product();
+        product.setCurrentPrice(9.99);
+        product.setDataOrigin("Amazon");
+        product.setProductId("12345");
+
+        // Act and Assert
+        assertDoesNotThrow(() -> ProductValidator.validate(product));
+    }
+
+    @Test
+    void isInValidDataOrigins_ValidDataOrigin_ReturnsTrue() {
+        // Arrange
+        String dataOrigin = "Amazon";
+
+        // Act
+        boolean result = ProductValidator.isInValidDataOrigins(dataOrigin);
+
+        // Assert
+        assertTrue(result);
+    }
+
+    @Test
+    void isInValidDataOrigins_InvalidDataOrigin_ReturnsFalse() {
+        // Arrange
+        String dataOrigin = "UnknownOrigin";
+
+        // Act
+        boolean result = ProductValidator.isInValidDataOrigins(dataOrigin);
+
+        // Assert
+        assertFalse(result);
+    }
+
+    @ParameterizedTest
+    @MethodSource("invalidProductProvider")
+    void validate_InvalidProduct_ThrowsInvalidProductException(Product product) {
+        // Act and Assert
+        assertThrows(InvalidProductException.class, () -> ProductValidator.validate(product));
+    }
+
+    static Stream<Product> invalidProductProvider() {
+        return Stream.of(
+                createProductWithZeroPrice(),
+                createProductWithUnknownDataOrigin(),
+                createProductWithEmptyProductId());
+    }
+
+    private static Product createProductWithZeroPrice() {
+        Product product = new Product();
+        product.setCurrentPrice(0.00);
+        product.setDataOrigin("Amazon");
+        product.setProductId("12345");
+        return product;
+    }
+
+    private static Product createProductWithUnknownDataOrigin() {
+        Product product = new Product();
+        product.setCurrentPrice(9.99);
+        product.setDataOrigin("UnknownOrigin");
+        product.setProductId("12345");
+        return product;
+    }
+
+    private static Product createProductWithEmptyProductId() {
+        Product product = new Product();
+        product.setCurrentPrice(9.99);
+        product.setDataOrigin("Amazon");
+        product.setProductId("");
+        return product;
+    }
+}

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;
 
@@ -13,7 +14,7 @@ import org.junit.jupiter.api.Test;
 
 class ConfigImplTest {
     private Config config;
-    private final static String TESTDATA_PATH = "testResources/testdata.properties";
+    private final static String TESTDATA_PATH = "src/test/resources/testdata.properties";
     private final static String TESTDATA_KEY = "API_KEY";
     private final static String TESTDATA_VAL = "keyIsHere";
 
@@ -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);
         });
@@ -74,7 +77,7 @@ class ConfigImplTest {
     @Test
     void testLoadConfigSuccessfully() {
         try {
-            config.setConfigLocation("testResources/testdata.properties");
+            config.setConfigLocation("src/test/resources/testdata.properties");
             config.loadConfig();
             assertEquals(TESTDATA_VAL, config.getProperty(TESTDATA_KEY));
         } catch (ConfigurationException e) {
@@ -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());
+    }
 }

src/test/java/de/rwu/easydrop/util/ConfigTest.java

@@ -2,6 +2,7 @@ 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.assertSame;
 import static org.mockito.Mockito.spy;
 
 import javax.naming.ConfigurationException;
@@ -20,17 +21,18 @@ class ConfigTest {
     }
 
     @Test
-    void testGetInstanceNull() {
+    void testGetInstance() {
-        config = null;
-
         Config newConfig = Config.getInstance();
         assertNotNull(newConfig);
     }
 
     @Test
-    void testGetInstanceNotNull() {
+    void testGetInstanceEquality() {
-        Config newConfig = Config.getInstance();
+        // Create "two" instances to check validity of Singleton pattern
-        assertNotNull(newConfig);
+        Config instance1 = Config.getInstance();
+        Config instance2 = Config.getInstance();
+
+        assertSame(instance1, instance2, "Instances should be equal");
     }
 
     @Test

src/test/resources/empty.properties

@@ -0,0 +1 @@
+

src/test/resources/testdata.properties

@@ -0,0 +1,5 @@
+API_KEY=keyIsHere
+AMAZON_API_URL=THE_AMAZON_API_URL
+AMAZON_API_KEY=THE_AMAZON_API_KEY
+EBAY_API_URL=THE_EBAY_API_URL
+EBAY_API_KEY=THE_EBAY_API_KEY

testResources/testdata.properties

@@ -1 +0,0 @@
-API_KEY=keyIsHere