feature: simple application test

pom.xml

@@ -38,6 +38,10 @@
     </dependencyManagement>
 
     <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-webflux</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-actuator</artifactId>

src/test/java/tk/antoine/roux/MainIT.java

@@ -0,0 +1,73 @@
+package tk.antoine.roux;
+
+import org.assertj.core.api.Assertions;
+import org.hamcrest.Matchers;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.actuate.observability.AutoConfigureObservability;
+import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.http.MediaType;
+import org.springframework.test.web.reactive.server.EntityExchangeResult;
+import org.springframework.test.web.reactive.server.FluxExchangeResult;
+import org.springframework.test.web.reactive.server.WebTestClient;
+import org.springframework.test.web.reactive.server.WebTestClient.ResponseSpec;
+import org.springframework.test.web.servlet.ResultActions;
+import org.springframework.test.web.servlet.client.MockMvcWebTestClient;
+
+import java.util.regex.Pattern;
+
+import static org.hamcrest.Matchers.containsString;
+import static org.springframework.http.MediaType.APPLICATION_JSON;
+import static org.springframework.http.MediaType.TEXT_PLAIN;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@SpringBootTest
+@AutoConfigureWebTestClient
+@AutoConfigureObservability
+class MainIT {
+
+    @Autowired
+    private WebTestClient webClient;
+
+    @Test
+    @DisplayName("Check that actuator health endpoint return 200")
+    void actuatorHealth() {
+        // Given
+
+        // When
+        ResponseSpec result = webClient.get()
+            .uri("/api/health")
+            .accept(APPLICATION_JSON)
+            .exchange();
+
+        // Then
+        result.expectStatus().isOk();
+    }
+
+    @Test
+    @DisplayName("Check that actuator prometheus contain metric 'application_ready_time_seconds'")
+    void actuatorPrometheus() {
+        // Given
+
+        // When
+        ResponseSpec result = webClient.get()
+            .uri("/api/prometheus")
+            .accept(TEXT_PLAIN)
+            .exchange();
+
+        // Then
+        EntityExchangeResult<String> stringEntityExchangeResult = result
+            .expectStatus().isOk()
+            .expectBody(String.class)
+            .returnResult();
+
+        String responseBody = stringEntityExchangeResult.getResponseBody();
+        Assertions.assertThat(responseBody).containsPattern(
+            Pattern.compile("^application_ready_time_seconds.* [0-9]\\.[0-9]*$", Pattern.MULTILINE)
+        );
+    }
+}