Add a counter and a unit test for it

Author: monodot

src/main/java/com/tutorialworks/demos/springbootwithmetrics/GreetingController.java

@@ -32,6 +32,7 @@ public GreetingController(MeterRegistry registry) {
     @Timed(value = "greeting.time", description = "Time taken to return greeting",
             percentiles = {0.5, 0.90})
     public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
+        registry.counter("greetings.counter").increment();
         return new Greeting(counter.incrementAndGet(), String.format(template, name));
     }
 

src/test/java/com/tutorialworks/demos/springbootwithmetrics/SpringBootWithMetricsApplicationTests.java

@@ -1,13 +1,39 @@
 package com.tutorialworks.demos.springbootwithmetrics;
 
+import io.micrometer.core.instrument.MeterRegistry;
 import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.http.ResponseEntity;
 
-@SpringBootTest
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Basic integration tests to check that metrics are rendered.
+ */
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
 class SpringBootWithMetricsApplicationTests {
 
-	@Test
-	void contextLoads() {
-	}
+    @Autowired
+    private TestRestTemplate restTemplate;
+
+	@Autowired
+	MeterRegistry registry;
+
+	/**
+	 * Sends a test request to the Greeting API, then asserts that the counter
+	 * has increased to 1.
+	 * @throws InterruptedException
+	 */
+    @Test
+    void testMetricsRequestCounterIncreases() throws InterruptedException {
+		// Make a test request to the Greeting service
+		ResponseEntity<String> response = this.restTemplate.getForEntity("/greeting", String.class);
+
+		assertThat(registry.get("greetings.counter").counter().count()).isEqualTo(1);
+    }
 
 }