feat: add RestClient learning test (cho-log#18)

* build: upgrade gradle version for 8.1.1

* feat: add RestClient learning test

* feat: add RestClient learning test with initial status

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.4-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.1.1-bin.zip
+networkTimeout=10000
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -55,7 +55,7 @@
 #       Darwin, MinGW, and NonStop.
 #
 #   (3) This script is generated from the Groovy template
-#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
 #       within the Gradle project.
 #
 #       You can find Gradle at https://github.com/gradle/gradle/.
@@ -80,13 +80,10 @@ do
     esac
 done
 
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-APP_NAME="Gradle"
+# This is normally unused
+# shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -143,12 +140,16 @@ fi
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
     case $MAX_FD in #(
       max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
         MAX_FD=$( ulimit -H -n ) ||
             warn "Could not query maximum file descriptor limit"
     esac
     case $MAX_FD in  #(
       '' | soft) :;; #(
       *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
         ulimit -n "$MAX_FD" ||
             warn "Could not set maximum file descriptor limit to $MAX_FD"
     esac
@@ -193,6 +194,10 @@ if "$cygwin" || "$msys" ; then
     done
 fi
 
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
 # Collect all arguments for the java command;
 #   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
 #     shell script including quotes and variable substitutions, so put them in
@@ -205,6 +210,12 @@ set -- \
         org.gradle.wrapper.GradleWrapperMain \
         "$@"
 
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
 # Use "xargs" to parse quoted args.
 #
 # With -n1 it outputs one arg per line, with the quotes and backslashes removed.

gradlew.bat

@@ -14,7 +14,7 @@
 @rem limitations under the License.
 @rem
 
-@if "%DEBUG%" == "" @echo off
+@if "%DEBUG%"=="" @echo off
 @rem ##########################################################################
 @rem
 @rem  Gradle startup script for Windows
@@ -25,7 +25,8 @@
 if "%OS%"=="Windows_NT" setlocal
 
 set DIRNAME=%~dp0
-if "%DIRNAME%" == "" set DIRNAME=.
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
 set APP_BASE_NAME=%~n0
 set APP_HOME=%DIRNAME%
 
@@ -40,7 +41,7 @@ if defined JAVA_HOME goto findJavaFromJavaHome
 
 set JAVA_EXE=java.exe
 %JAVA_EXE% -version >NUL 2>&1
-if "%ERRORLEVEL%" == "0" goto execute
+if %ERRORLEVEL% equ 0 goto execute
 
 echo.
 echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
@@ -75,13 +76,15 @@ set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
 
 :end
 @rem End local scope for the variables with windows NT shell
-if "%ERRORLEVEL%"=="0" goto mainEnd
+if %ERRORLEVEL% equ 0 goto mainEnd
 
 :fail
 rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
 rem the _cmd.exe /c_ return code!
-if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
-exit /b 1
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
 
 :mainEnd
 if "%OS%"=="Windows_NT" endlocal

settings.gradle

@@ -20,3 +20,5 @@ include 'spring-data-jpa-2:initial'
 include 'spring-data-jpa-2:complete'
 include 'spring-auth-1:initial'
 include 'spring-auth-1:complete'
+include 'spring-http-client-1:initial'
+include 'spring-http-client-1:complete'

spring-http-client-1/complete/README.md

@@ -0,0 +1,75 @@
+# 1. Spring의 HTTP 클라이언트
+
+<br>
+
+스프링 프레임워크는 다양한 HTTP 클라이언트를 제공하여 애플리케이션이 외부 API와 통신할 수 있도록 합니다. 
+스프링이 제공하는 HTTP 클라이언트에는 `RestClient`, `WebClient`, `RestTemplate` 이 있습니다.
+
+이 문서에서는 스프링 6.1 버전에 추가된 `RestClient` 에 대해 다룹니다.
+
+<br>
+
+### 참조
+
+- [Spring - REST Clients](https://docs.spring.io/spring-framework/reference/integration/rest-clients.html)
+- [Spring blog - New in Spring 6.1: RestClient](https://spring.io/blog/2023/07/13/new-in-spring-6-1-restclient)
+
+<br>
+
+# 2. GET 요청 하기
+
+<br>
+
+`RestClient` 의 `get()` 메서드를 사용해 GET 요청을 할 수 있습니다.
+
+<br>
+
+### 학습 테스트
+- 테스트 메서드: `cholog.RestClientTest.testGetTodos`
+- 수행 방법
+  - `cholog.TodoRestClient.getTodos` 을 이용하여 학습 테스트를 성공시키세요.
+    - `TodoRestClient` 의 restClient 를 사용하여 Todo 목록을 조회합니다.
+      - Todo 목록 조회 url: http://jsonplaceholder.typicode.com/todos
+    - 외부 API의 host는 `RestClientConfig` 에 설정되어 있습니다.
+
+<br>
+
+# 3. GET 요청의 응답 변환하기
+
+<br>
+
+`RestClient` 의 `body()` 메서드를 사용해 응답을 원하는 POJO로 변환할 수 있습니다.
+
+<br>
+
+### 학습 테스트
+- 테스트 메서드: `cholog.RestClientTest.testGetTodoWithId`
+- 수행 방법
+  - `cholog.TodoRestClient.getTodoById` 을 이용하여 학습 테스트를 성공시키세요.
+    - `TodoRestClient` 의 restClient 를 사용하여 특정 id를 가진 Todo를 조회합니다.
+      - Todo 조회 url: http://jsonplaceholder.typicode.com/todos/1
+    - 응답 Body로 받은 `userId`, `id`, `title`, `completed` 값이 잘 매핑되도록 `Todo` 를 수정합니다.
+
+<br>
+
+# 4. 예외 처리
+
+<br>
+
+`RestClient` 의 `onStatus()` 메서드를 사용해 HTTP 응답 코드에 따라 예외처리를 할 수 있습니다.
+
+<br>
+
+### 학습 테스트
+- 테스트 메서드: `cholog.RestClientTest.testGetTodoWithNonExistentId`
+- 수행 방법
+  - `cholog.TodoRestClient.getTodoById` 을 이용하여 학습 테스트를 성공시키세요.
+    - 존재하지 않는 id에 대한 조회 요청을 했을 때, `TodoException.NotFound` 예외가 발생하도록 합니다.
+
+<br>
+
+# 5. 더 생각해보기
+
+- 스프링이 제공하는 HTTP 클라이언트에는 각각 다른 성격과 사용 방법을 가지고 있습니다. 
+  - `RestClient` 외의 다른 클라이언트에 대한 학습 테스트를 작성해 보며 차이점을 느껴봅니다. 
+  - 각 클라이언트의 특징을 찾아보고 어떤 상황에 어떤 클라이언트를 택하는게 좋을지 생각해 봅니다. 

spring-http-client-1/complete/build.gradle

@@ -0,0 +1,22 @@
+plugins {
+    id 'org.springframework.boot' version '3.2.5'
+    id 'io.spring.dependency-management' version '1.1.4'
+    id 'java'
+}
+
+group = 'cholog'
+version = '0.0.1-SNAPSHOT'
+sourceCompatibility = '17'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation 'org.springframework.boot:spring-boot-starter-web'
+    testImplementation 'org.springframework.boot:spring-boot-starter-test'
+}
+
+test {
+    useJUnitPlatform()
+}

spring-http-client-1/complete/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = 'spring-http-client-1'

spring-http-client-1/complete/src/main/java/cholog/RestClientConfig.java

@@ -0,0 +1,15 @@
+package cholog;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.client.RestClient;
+
+@Configuration
+public class RestClientConfig {
+    @Bean
+    public TodoRestClient todoRestClient() {
+        return new TodoRestClient(
+                RestClient.builder().baseUrl("http://jsonplaceholder.typicode.com").build()
+        );
+    }
+}

spring-http-client-1/complete/src/main/java/cholog/SpringClientApplication.java

@@ -0,0 +1,13 @@
+package cholog;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SpringClientApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(SpringClientApplication.class, args);
+    }
+
+}

spring-http-client-1/complete/src/main/java/cholog/Todo.java

@@ -0,0 +1,24 @@
+package cholog;
+
+public class Todo {
+    private Long id;
+    private Long userId;
+    private String title;
+    private boolean completed;
+
+    public Long getId() {
+        return id;
+    }
+
+    public Long getUserId() {
+        return userId;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public boolean isCompleted() {
+        return completed;
+    }
+}

spring-http-client-1/complete/src/main/java/cholog/TodoException.java

@@ -0,0 +1,13 @@
+package cholog;
+
+public class TodoException extends RuntimeException {
+    public TodoException(String message) {
+        super(message);
+    }
+
+    public static class NotFound extends TodoException {
+        public NotFound(Long id) {
+            super("Todo not found with id: " + id);
+        }
+    }
+}

spring-http-client-1/complete/src/main/java/cholog/TodoRestClient.java

@@ -0,0 +1,33 @@
+package cholog;
+
+import org.springframework.web.client.RestClient;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class TodoRestClient {
+    private final RestClient restClient;
+
+    public TodoRestClient(RestClient restClient) {
+        this.restClient = restClient;
+    }
+
+    public List<Todo> getTodos() {
+        Todo[] todoBody = restClient.get()
+                .uri("/todos")
+                .retrieve()
+                .body(Todo[].class);
+
+        return Arrays.asList(todoBody);
+    }
+
+    public Todo getTodoById(Long id) {
+        return restClient.get()
+                .uri("/todos/{id}", id)
+                .retrieve()
+                .onStatus(status -> status.value() == 404, (req, res) -> {
+                  throw new TodoException.NotFound(id);
+                })
+                .body(Todo.class);
+    }
+}

spring-http-client-1/complete/src/main/resources/application.properties

@@ -0,0 +1 @@
+

spring-http-client-1/complete/src/test/java/cholog/RestClientTest.java

@@ -0,0 +1,37 @@
+package cholog;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+@SpringBootTest
+public class RestClientTest {
+
+    @Autowired
+    private TodoRestClient todoRestClient;
+
+    @Test
+    public void testGetTodos() {
+        List<Todo> todos = todoRestClient.getTodos();
+        assertThat(todos).isNotEmpty();
+    }
+
+    @Test
+    public void testGetTodoWithId() {
+        Todo todo = todoRestClient.getTodoById(1L);
+        assertThat(todo.getTitle()).isNotEmpty();
+    }
+
+    @Test
+    public void testGetTodoWithNonExistentId() {
+        Long nonExistentId = 9999L;
+
+        assertThatThrownBy(() -> todoRestClient.getTodoById(nonExistentId))
+                .isInstanceOf(TodoException.NotFound.class);
+    }
+}