Add startup time metrics

See gh-27878

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/startup/StartupTimeMetricsTests.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2012-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.actuate.metrics.startup;
+
+import java.time.Duration;
+import java.util.concurrent.TimeUnit;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.Tags;
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.boot.context.event.ApplicationStartedEvent;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link StartupTimeMetrics}.
+ *
+ * @author Chris Bono
+ */
+class StartupTimeMetricsTests {
+
+	private static final long APP_STARTED_TIME_MS = 2500;
+
+	private static final long APP_RUNNING_TIME_MS = 2900;
+
+	private MeterRegistry registry;
+
+	private StartupTimeMetrics metrics;
+
+	@BeforeEach
+	void prepareUnit() {
+		this.registry = new SimpleMeterRegistry();
+		this.metrics = new StartupTimeMetrics(this.registry);
+	}
+
+	@Test
+	void metricsRecordedWithoutCustomTags() {
+		this.metrics.onApplicationEvent(applicationStartedEvent(APP_STARTED_TIME_MS));
+		this.metrics.onApplicationEvent(applicationReadyEvent(APP_RUNNING_TIME_MS));
+		assertMetricExistsWithValue("application.started.time", APP_STARTED_TIME_MS);
+		assertMetricExistsWithValue("application.ready.time", APP_RUNNING_TIME_MS);
+	}
+
+	@Test
+	void metricsRecordedWithCustomTagsAndMetricNames() {
+		Tags tags = Tags.of("foo", "bar");
+		this.metrics = new StartupTimeMetrics(this.registry, tags, "m1", "m2");
+		this.metrics.onApplicationEvent(applicationStartedEvent(APP_STARTED_TIME_MS));
+		this.metrics.onApplicationEvent(applicationReadyEvent(APP_RUNNING_TIME_MS));
+		assertMetricExistsWithCustomTagsAndValue("m1", tags, APP_STARTED_TIME_MS);
+		assertMetricExistsWithCustomTagsAndValue("m2", tags, APP_RUNNING_TIME_MS);
+	}
+
+	@Test
+	void metricsRecordedWithoutMainAppClassTagWhenMainAppClassNotAvailable() {
+		this.metrics.onApplicationEvent(applicationStartedEvent(APP_STARTED_TIME_MS));
+		this.metrics.onApplicationEvent(applicationReadyEvent(APP_RUNNING_TIME_MS));
+		assertThat(this.registry.find("application.started.time").timeGauge()).isNotNull();
+		assertThat(this.registry.find("application.ready.time").timeGauge()).isNotNull();
+	}
+
+	@Test
+	void metricsNotRecordedWhenStartupTimeNotAvailable() {
+		this.metrics.onApplicationEvent(applicationStartedEvent(null));
+		this.metrics.onApplicationEvent(applicationReadyEvent(null));
+		assertThat(this.registry.find("application.started.time").timeGauge()).isNull();
+		assertThat(this.registry.find("application.ready.time").timeGauge()).isNull();
+	}
+
+	private ApplicationStartedEvent applicationStartedEvent(Long startupTimeMs) {
+		SpringApplication application = mock(SpringApplication.class);
+		doReturn(TestMainApplication.class).when(application).getMainApplicationClass();
+		return new ApplicationStartedEvent(application, null, null,
+				(startupTimeMs != null) ? Duration.ofMillis(startupTimeMs) : null);
+	}
+
+	private ApplicationReadyEvent applicationReadyEvent(Long startupTimeMs) {
+		SpringApplication application = mock(SpringApplication.class);
+		doReturn(TestMainApplication.class).when(application).getMainApplicationClass();
+		return new ApplicationReadyEvent(application, null, null,
+				(startupTimeMs != null) ? Duration.ofMillis(startupTimeMs) : null);
+	}
+
+	private void assertMetricExistsWithValue(String metricName, double expectedValueInMillis) {
+		assertMetricExistsWithCustomTagsAndValue(metricName, Tags.empty(), expectedValueInMillis);
+	}
+
+	private void assertMetricExistsWithCustomTagsAndValue(String metricName, Tags expectedCustomTags,
+			double expectedValueInMillis) {
+		assertThat(this.registry.find(metricName)
+				.tags(Tags.concat(expectedCustomTags, "main-application-class", TestMainApplication.class.getName()))
+				.timeGauge()).isNotNull().extracting((m) -> m.value(TimeUnit.MILLISECONDS))
+						.isEqualTo(expectedValueInMillis);
+	}
+
+	static class TestMainApplication {
+
+	}
+
+}