Java Application Integration testing with JUnit: UserService and OrderService Interaction

Java Unit Test: Exercise-10 with Solution

Write a Java program that create tests that verify the interaction between different components or modules in your application.

Sample Solution:

Java Code:

// ApplicationIntegrationTest.java

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.JUnitCore;
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;

import static org.junit.Assert.assertEquals;

// Component 1: UserService
class UserService {
    public String getUserFullName(int userId) {
        // Simulate fetching user data from a database
        // In a real application, this would involve interacting with a database or another service
        return "John Doe"; // Assume a static user for simplicity
    }
}

// Component 2: OrderService
class OrderService {
    private UserService userService;

    public OrderService(UserService userService) {
        this.userService = userService;
    }

    public String getOrderDetails(int orderId) {
        // Simulate fetching order details from a database
        // In a real application, this would involve interacting with a database or another service
        int userId = 1; // Assume a static user for simplicity
        String userName = userService.getUserFullName(userId);
        return "Order #123 for User: " + userName;
    }
}

// JUnit Test Class
public class ApplicationIntegrationTest {

    private UserService userService;
    private OrderService orderService;

    @Before
    public void setUp() {
        userService = new UserService();
        orderService = new OrderService(userService);
    }

    @Test
    public void testGetOrderDetails() {
        // Test the interaction between UserService and OrderService
        String orderDetails = orderService.getOrderDetails(123);

        // Verify the result
        assertEquals("Order #123 for User: John Doe", orderDetails);
    }

    public static void main(String[] args) {
        // Run the JUnit test
        Result result = JUnitCore.runClasses(ApplicationIntegrationTest.class);

        // Check if there are any failures
        if (result.getFailureCount() > 0) {
            System.out.println("Test failed:");

            // Print details of failures
            for (Failure failure : result.getFailures()) {
                System.out.println(failure.toString());
            }
        } else {
            System.out.println("All tests passed successfully.");
        }
    }
}

Sample Output:

All tests passed successfully

Explanation:

The above Java code shows an integration test using JUnit to verify the interaction between two components in an application. Here's a brief explanation:

• Components:
• UserService: Simulates fetching user data. In a real application, this would involve interacting with a database or another service.
• OrderService: Uses "UserService" and simulates fetching order details. It involves interacting with a database or another service.
• Test Class (ApplicationIntegrationTest):
• Uses JUnit annotations (@Before, @Test) for setup and testing.
• setUp(): Initializes instances of "UserService" and "OrderService" before each test.
• testGetOrderDetails(): Tests the interaction between "UserService" and OrderService. It fetches order details using "OrderService" and verifies the result using "assertEquals".
• Main Method:
• main(): Runs the JUnit test using JUnitCore.runClasses().
• Checks for test failures and prints details if any.

Flowchart:

Java Code Editor:

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