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https://github.com/thisoecode/springacademy_cashcard-rest-api

Spring Academy example project step-by-step following repo
https://github.com/thisoecode/springacademy_cashcard-rest-api

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Spring Academy example project step-by-step following repo

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README 

        
> This readme file is a [Spring Academy](https://spring.academy/) learning note. 
 The coding following Spring Academy was done in VS Code instead of Spring Academy Lab.



> Learning & memoing starts on 2024-02-07, by Thisoe.



> ### This repo is abandoned

> - [Thisoe's main Spring learning repo has moved here.](https://github.com/ThisoeCode/springboot-tut_following-devtiro)

> - This repo is currently stopped. I found Spring Academy a bit not beginner friendly-ish, and at the same time, a few steps are not working on my Windows machine. 
 But this repo will be reserving archived since new SpringBoot learning repos are going to have tag-links to this file.



# 1. Spring Initializr

https://start.spring.io/



# 2. [Set the Goal](https://spring.academy/courses/building-a-rest-api-with-spring-boot/lessons/data-contracts)

Goal API:

```yaml

Request:

  URI: /cashcards/{id}

  HTTP Verb: GET

  Body: None



Response:

  HTTP Status:

    200 OK if the user is authorized and the Cash Card was successfully retrieved

    401 UNAUTHORIZED if the user is unauthenticated or unauthorized

    404 NOT FOUND if the user is authenticated and authorized but the Cash Card cannot be found

  Response Body Type: JSON

  Example Response Body:

    {

      "id": 99,

      "amount": 123.45

    }

```



# 3. [Testing First](https://spring.academy/courses/building-a-rest-api-with-spring-boot/lessons/test-first)

- Test Driven Development (TDD)

- The Red, Green, Refactor Loop

  1. Red: Write a failing test for the desired functionality.

  2. Green: Implement the simplest thing that can work to make the test pass.

  3. Refactor: Look for opportunities to simplify, reduce duplication, or otherwise improve the code without changing any behavior—to refactor.

  4. Repeat!



## [Lab](https://spring.academy/courses/building-a-rest-api-with-spring-boot/lessons/test-first-lab/lab)



1. Write a Failing Test

```java

package example.cashcard;



import org.junit.jupiter.api.Test;

import static org.assertj.core.api.Assertions.assertThat;



class CashCardJsonTest {

   @Test

   void myFirstTest() {

      assertThat(1).isEqualTo(42);

   }

}

```



[Install Gradle](https://gradle.org/install/) to run the test.

```bash

# Test after installation & setting env var. 

gradle -v

# Gradle 8.6



gradle init

# Selected

  # Generate a Gradle build from Maven build? y

  # Build script DSL: Groovy



gradle test

# ...

# BUILD SUCCESSFUL in 13s

# 4 actionable tasks: 4 executed

```

`4 executed` means that this is a **failed** test.

To "fix" it, change the `1` in `assertThat()` to `42`.

```java

class CashCardJsonTest {

   @Test

   void myFirstTest() {

      assertThat(42).isEqualTo(42);

   }

}

```

Now, it passes.

```bash

gradle test

# ...

# BUILD SUCCESSFUL in 1s

# 4 actionable tasks: 2 executed, 2 up-to-date

```



This whole process above, is called a "test-first development".



2. Testing the Data Contract



```java

package example.cashcard;



import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.boot.test.autoconfigure.json.JsonTest;

import org.springframework.boot.test.json.JacksonTester;

import java.io.IOException;

import static org.assertj.core.api.Assertions.assertThat;



@JsonTest // marks the `CashCardJsonTest` as a test class

class CashCardJsonTest {



  @Autowired // directs Spring to create an object of the requested type

  private JacksonTester json;

  // `JacksonTester` handles serialization and deserialization of JSON objects



  @Test

  void cashCardSerializationTest() throws IOException {

    CashCard cashCard = new CashCard(99L, 123.45);

    assertThat(json.write(cashCard)).isStrictlyEqualToJson("expected.json");

    assertThat(json.write(cashCard)).hasJsonPathNumberValue("@.id");

    assertThat(json.write(cashCard)).extractingJsonPathNumberValue("@.id")

      .isEqualTo(99);

    assertThat(json.write(cashCard)).hasJsonPathNumberValue("@.amount");

    assertThat(json.write(cashCard)).extractingJsonPathNumberValue("@.amount")

      .isEqualTo(123.45);

  }

}

```



> Terminal run test and get failure message.



We yet neither have created `CashCard` class, nor the `expected.json` file. Let's create it **in the `main/` directory**.



  1. Create file `src/main/java/example/cashcard/CashCard.java` and add content:

```java

package example.cashcard;



record CashCard(Long id, Double amount) {

}

```

  2. Create file `src/test/resources/example/cashcard/expected.json` (**right click `test` directory, select `New File`, type in `resources/example/cashcard/expected.json`**) and add content:

```json

{}

```



> Terminal run test, and...



```bash

./gradlew test

# ...

# Task :compileTestJava FAILED

#   error: records are not supported in -source 8

#   (use -source 16 or higher to enable records)

# ...

```

This error is unexpected — the tutorial did not mention this.



After Googling and GPTing, I found the solution:

  1. Check Java version in terminal:

```bash

java -version

# java version "17.0.10" 2024-01-16 LTS

```

  2. Go to `build.gradle`, find:

```js

java.sourceCompatibility = JavaVersion.VERSION_1_8

```

  3. Change `VERSION_1_8` to `VERSION_17`.



After these, run the test again.

```bash

./gradlew test --warning-mode all

# BUILD SUCCESSFUL in 931ms

```



Different from tutorial again: this expects a comparison failure, but got a success.








___

> Repo has stopped updating.