Disable metrics export in integration tests

This commit introduces a new property to globally disable metrics
export. In integration tests, this property is automatically set to
disable everything but in-memory metrics.

This commit also introduces a `@AutoConfigureMetrics` annotation that
can be used for integration tests that require metrics export to operate
as they would in an application.

See gh-21658

spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/metrics/AutoConfigureMetrics.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2012-2019 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.test.autoconfigure.metrics;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation that can be applied to a test class to enable auto-configuration for metrics
+ * exporters.
+ *
+ * @author Chris Bono
+ * @since 2.4.0
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Inherited
+public @interface AutoConfigureMetrics {
+
+}

spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/metrics/ExcludeMetricExportersContextCustomizerFactory.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2012-2019 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.test.autoconfigure.metrics;
+
+import java.util.List;
+
+import org.springframework.boot.test.util.TestPropertyValues;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.core.annotation.MergedAnnotations;
+import org.springframework.core.annotation.MergedAnnotations.SearchStrategy;
+import org.springframework.test.context.ContextConfigurationAttributes;
+import org.springframework.test.context.ContextCustomizer;
+import org.springframework.test.context.ContextCustomizerFactory;
+import org.springframework.test.context.MergedContextConfiguration;
+
+/**
+ * {@link ContextCustomizerFactory} that creates a customizer that globally disables
+ * metrics exporters unless the {@link AutoConfigureMetrics} annotation is specified on
+ * the test class.
+ *
+ * @author Chris Bono
+ */
+class ExcludeMetricExportersContextCustomizerFactory implements ContextCustomizerFactory {
+
+	@Override
+	public ContextCustomizer createContextCustomizer(Class<?> testClass,
+			List<ContextConfigurationAttributes> configAttributes) {
+		boolean metricExportersEnabled = MergedAnnotations.from(testClass, SearchStrategy.TYPE_HIERARCHY)
+				.get(AutoConfigureMetrics.class).isPresent();
+		return !metricExportersEnabled ? new ExcludeMetricExportersContextCustomizer() : null;
+	}
+
+	static class ExcludeMetricExportersContextCustomizer implements ContextCustomizer {
+
+		@Override
+		public void customizeContext(ConfigurableApplicationContext context,
+				MergedContextConfiguration mergedContextConfiguration) {
+			TestPropertyValues
+					.of("management.metrics.export.enabled=false", "management.metrics.export.simple.enabled=true")
+					.applyTo(context);
+		}
+
+		@Override
+		public boolean equals(Object obj) {
+			return (obj != null) && (getClass() == obj.getClass());
+		}
+
+		@Override
+		public int hashCode() {
+			return getClass().hashCode();
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-test-autoconfigure/src/main/java/org/springframework/boot/test/autoconfigure/metrics/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2019 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.
+ */
+
+/**
+ * Test auto-configuration support for actuator metrics.
+ */
+package org.springframework.boot.test.autoconfigure.metrics;

spring-boot-project/spring-boot-test-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -186,6 +186,7 @@ org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExe
 org.springframework.test.context.ContextCustomizerFactory=\
 org.springframework.boot.test.autoconfigure.OverrideAutoConfigurationContextCustomizerFactory,\
 org.springframework.boot.test.autoconfigure.filter.TypeExcludeFiltersContextCustomizerFactory,\
+org.springframework.boot.test.autoconfigure.metrics.ExcludeMetricExportersContextCustomizerFactory,\
 org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizerFactory,\
 org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizerFactory