Blind auction system

Project Basic Structure

The folder structure of the Blind Auction System repository is as follows:

root
├── user-service
│   ├── src
│   │   └── main
│   │       └── java/com/yourcompany/users
│   │           └── UserController.java
│   │           └── User.java
│   │           └── UserRepository.java
│   └── pom.xml
│
├── auction-service
│   ├── src
│   │   └── main
│   │       └── java/com/yourcompany/auctions
│   │           └── AuctionController.java
│   │           └── ProductController.java
│   │           └── Auction.java
│   │           └── Product.java
│   │           └── Bid.java
│   │           └── AuctionRepository.java
│   │           └── BidRepository.java
│   │           └── ProductRepository.java
│   └── pom.xml
│
└── pom.xml

This structure includes two services: user-service and auction-service, each with its respective Java files and Maven configuration (pom.xml).

Run the Services

1. Start the user-service:

   cd user-service
   mvn spring-boot:run
   

2. Start the auction-service:

   cd ../auction-service
   mvn spring-boot:run
   

Now, both services are up and running. You can interact with the API endpoints (e.g., /auctions/ping, /users/ping, /users/validate) using tools like Postman or curl.

API Details and Endpoints explanation:

Auction Service

1. createAuction:

   • Validates the seller's token by calling the User Service.
   • If validation passes, saves the auction details and sets the seller’s token.

2. placeBid:

   • Validates the buyer’s token.
   • Ensures that the bid amount meets the minimum bid price.
   • Associates the bid with the auction and saves it.

3. getAllAuctions:

   • Returns a list of all auctions available for bidding.

4. endAuction:

   • Ends the auction by finding the highest bid.
   • In case of a tie on the bid amount, the earliest bid (timestamp) is selected as the winner.

5. validateUserToken:

   • Calls the User Service to validate user tokens by role type (buyer or seller).
   • Throws an error if the token is invalid or the validation service fails.

6. Auctions Endpoints:

   • /auctions/register : Creates a new auction with a seller’s token and minimum bid requirement.
   • /auctions/list : Lists all open auctions.
   • /auctions/{auctionId}/bid : Places a bid on an auction if the bid meets the minimum amount and the auction is open.
   • /auctions/{auctionId}/end : Closes the auction and returns the winning bid, if any. The first highest bid in descending order is considered the winner.

7. getAllProducts:

   • Returns a list of all products.

Notes - The RestTemplate in validateUserToken simulates a call to the UserService to verify tokens. - Error Handling: Error messages are thrown if auction or bid validation fails. - Comparators: endAuction selects the highest bid and resolves ties by timestamp.

User Service

1. Token Map:

   • userTokens is a Map<String, String> that simulates a database of user tokens mapped to user types (e.g., "seller" or "buyer").
   • For this example, tokens are pre-populated. In a real application, these would likely be stored in a database or managed by an authentication service.

2. validateUserToken Endpoint:

   • URL: /users/validate
   • Parameters:
     • token: The token to validate.
     • type: Expected type of user ("seller" or "buyer").

3. Validation Logic:

   • Checks if the provided token exists in the userTokens map.
   • Verifies that the token corresponds to the correct user type (buyer or seller).

4. Return:

   • Returns "Valid User" if the token and type match.
   • Returns "Invalid Token" if the token doesn’t exist in the map.
   • Returns "Invalid User Type" if the token exists but is for the wrong user type.

Sample Data Pre-population

To pre-populate the database, Add a CommandLineRunner bean to insert sample users and auction when the application starts:

@Bean
CommandLineRunner initDatabase(UserRepository userRepository) { 

}

@Bean
CommandLineRunner initDatabase(ProductRepository productRepository, AuctionRepository auctionRepository) {
	return args -> {
		
		List<Product> listOfProducts = new ArrayList<>();
		.....
		productRepository.saveAll(listOfProducts); 
		
		auctionRepository.save(new Auction(....));
	};
}

Test Cases

User service API endpoints JUnit Test cases

• testGetPing(): Validates that the /ping endpoint returns the expected string.
• testValidateToken_ValidUser(): Mocks a valid user return from userService.validateToken() and checks if the response is "Valid User".
• testValidateToken_InvalidUser(): Mocks a null return from userService.validateToken() and verifies that the response is "Invalid User".

Make sure JUnit and Mockito dependencies to successfully execute these tests.

User service services layer JUnit Test cases

• testValidateToken_Valid(): Verifies that a valid token returns a non-null user.
• testValidateToken_Invalid(): Tests that an invalid token throws a RuntimeException with the message "Invalid token".

This structure uses Mockito to mock the UserRepository and validate the behavior of validateToken().

Auction service API endpoints JUnit Test cases ...