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Lab 4 - Dependency Injection


Modify the CoffeeOrderApiController so that you can return coffee order information from the CoffeeOrderRepository via dependency injection.

Spring Annotation Reference

This reference of annotations might be helpful:

Add Failing Unit Test

  1. Open CoffeeOrderApiController and create a constructor that takes a dependency on CoffeeOrderRepository as a parameter.

    • Make sure to save the incoming reference to a member (instance) variable
  2. Create a new test class named CoffeeOrderApiControllerTest and copy the contents below

    package com.welltestedlearning.cvm;
    import org.junit.Test;
    import static org.assertj.core.api.Assertions.assertThat;
    public class CoffeeOrderApiControllerTest {
      public void testGetMapping() throws Exception {
        CoffeeOrderRepository coffeeOrderRepository = new FakeCoffeeOrderRepository();
        CoffeeOrder coffeeOrder = new CoffeeOrder();
        CoffeeOrderApiController controller = new CoffeeOrderApiController(coffeeOrderRepository);
        CoffeeOrderResponse coffeeOrderResponse = controller.coffeeOrderInfo("123");
        // medium coffee is 150 cents
  3. Run this test, which should fail. The next section will make it pass.

Lookup CoffeeOrder ID in Repository

  1. Open the CoffeeOrderApiController class

  2. In the coffeeOrderInfo method, use the coffeeOrderId that's passed in to:

    1. Find the CoffeeOrder from the CoffeeOrderRepository by the id using findOne()

    2. Convert it to an CoffeeOrderResponse and return it

  3. Run the CoffeeOrderApiControllerTest and it should now pass.

Autowire Repository

  1. Add the @Repository annotation to FakeCoffeeOrderRepository so that Spring can find and create it during the automatic dependency injection ("autowire") process.

Sample Data in Repository

  1. To "pre-load" some coffee order data into the repository, copy the entire file into the production code directory with the other classes.

  2. This would be in src/main/java/com/welltestedlearning/cvm

Add Integration Test

Copy the file into your src/test/java directory and run the tests.

If everything is wired properly, it should pass.

Try it Out

  1. See if you get the data by hitting this URL endpoint:


    You should see the JSON representation of the CoffeeOrder with ID of 1 and a price.

  2. Try adding more "sample" data to the CoffeeOrderDataLoader's run() method and the use your browser to hit the endpoint with different IDs.

Once you've completed the above steps,
check in with the instructor to review your code.