GH-865 Added initial test for Observability module

Resolves #865

spring-cloud-function-observability/src/main/java/org/springframework/cloud/function/observability/ObservationAutoConfiguration.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2022-2022 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.cloud.function.observability;
+
+import io.micrometer.observation.ObservationRegistry;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ *
+ * @author Oleg Zhurakousky
+ *
+ */
+@Configuration(proxyBeanMethods = false)
+public class ObservationAutoConfiguration {
+
+	@Bean
+	@ConditionalOnMissingBean
+	public ObservationFunctionAroundWrapper wrapper(ObservationRegistry registry) {
+		return new ObservationFunctionAroundWrapper(registry);
+	}
+}

spring-cloud-function-observability/src/main/java/org/springframework/cloud/function/observability/ObservationFunctionAroundWrapper.java

@@ -30,6 +30,7 @@ import org.springframework.cloud.function.context.catalog.SimpleFunctionRegistry
 
 /**
  * @author Marcin Grzejszczak
+ * @author Oleg Zhurakousky
  * @since 4.0.0
  */
 public class ObservationFunctionAroundWrapper extends FunctionAroundWrapper implements Observation.KeyValuesProviderAware<FunctionTagsProvider> {
@@ -70,7 +71,7 @@ public class ObservationFunctionAroundWrapper extends FunctionAroundWrapper impl
 			.keyValuesProvider(tagsProvider)
 			.observe(() -> {
 				Object r = message == null ? targetFunction.get() : targetFunction.apply(invocationMessage);
-				context.setOutput(r);
+				context.setModifiedOutput(r);
 				return r;
 			});
 		if (result == null) {

spring-cloud-function-observability/src/main/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
+org.springframework.cloud.function.observability.ObservationAutoConfiguration

spring-cloud-function-observability/src/test/java/org/springframework/cloud/function/observability/ObservationFunctionAroundWrapperTests.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2022-2022 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.cloud.function.observability;
+
+import java.util.function.Function;
+
+import io.micrometer.core.tck.TestObservationRegistry;
+import io.micrometer.core.tck.TestObservationRegistryAssert;
+import io.micrometer.observation.ObservationRegistry;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.cloud.function.context.FunctionCatalog;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.support.MessageBuilder;
+
+/**
+ *
+ * @author Oleg Zhurakousky
+ *
+ */
+public class ObservationFunctionAroundWrapperTests {
+
+	@Test
+	public void testSingleObservation() {
+		try (ConfigurableApplicationContext context = SpringApplication.run(SampleConfiguration.class, "")) {
+			FunctionCatalog catalog = context.getBean(FunctionCatalog.class);
+			Function<Message<String>, Message<byte[]>> uppercase = catalog.lookup("uppercase", "application/json");
+			Message<byte[]> result = uppercase.apply(MessageBuilder.withPayload("\"marcin\"").build());
+			System.out.println("Result: " + result);
+
+			TestObservationRegistry registry = context.getBean(TestObservationRegistry.class);
+			TestObservationRegistryAssert.then(registry).hasSingleObservationThat()
+					.hasNameEqualTo("spring.cloud.function");
+		}
+	}
+
+	@Configuration
+	@EnableAutoConfiguration
+	public static class SampleConfiguration {
+
+		@Bean
+		public ObservationRegistry testRegistry() {
+			return TestObservationRegistry.create();
+		}
+
+//		@Bean
+//		public ObservationFunctionAroundWrapper wrapper(ObservationRegistry registry) {
+//			return new ObservationFunctionAroundWrapper(registry);
+//		}
+
+		@Bean
+		public Function<String, String> uppercase() {
+			return v -> v.toUpperCase();
+		}
+	}
+}