Add FunctionInstanceInjector adapter test

spring-cloud-function-adapters/spring-cloud-function-adapter-azure/src/test/java/org/springframework/cloud/function/adapter/azure/injector/AzureFunctionInstanceInjectorTest.java

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+/*
+ * 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.adapter.azure.injector;
+
+import java.util.Iterator;
+import java.util.Optional;
+import java.util.ServiceLoader;
+import java.util.function.Function;
+
+import com.microsoft.azure.functions.ExecutionContext;
+import com.microsoft.azure.functions.HttpMethod;
+import com.microsoft.azure.functions.HttpRequestMessage;
+import com.microsoft.azure.functions.annotation.AuthorizationLevel;
+import com.microsoft.azure.functions.annotation.FunctionName;
+import com.microsoft.azure.functions.annotation.HttpTrigger;
+import com.microsoft.azure.functions.spi.inject.FunctionInstanceInjector;
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.AutoConfigurationExcludeFilter;
+import org.springframework.boot.context.TypeExcludeFilter;
+import org.springframework.cloud.function.adapter.azure.AzureFunctionInstanceInjector;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.ComponentScan.Filter;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.FilterType;
+
+/**
+ * @author Christian Tzolov
+ */
+public class AzureFunctionInstanceInjectorTest {
+
+	@Test
+	public void testFunctionInjector() throws Exception {
+
+		FunctionInstanceInjector injector = initializeFunctionInstanceInjector();
+		Assertions.assertThat(injector).isNotNull();
+		Assertions.assertThat(injector).isInstanceOf(AzureFunctionInstanceInjector.class);
+
+		System.setProperty("MAIN_CLASS", MyMainConfig.class.getName());
+
+		MyAzureTestFunction functionInstance = injector.getInstance(MyAzureTestFunction.class);
+		Assertions.assertThat(functionInstance).isNotNull();
+		Assertions.assertThat(functionInstance).isInstanceOf(MyAzureTestFunction.class);
+	}
+
+	private static FunctionInstanceInjector initializeFunctionInstanceInjector() {
+		FunctionInstanceInjector functionInstanceInjector = null;
+		ClassLoader prevContextClassLoader = Thread.currentThread().getContextClassLoader();
+		try {
+			Iterator<FunctionInstanceInjector> iterator = ServiceLoader.load(FunctionInstanceInjector.class).iterator();
+			if (iterator.hasNext()) {
+				functionInstanceInjector = iterator.next();
+				if (iterator.hasNext()) {
+					throw new RuntimeException(
+							"Customer function app has multiple FunctionInstanceInjector implementations");
+				}
+			}
+			else {
+				functionInstanceInjector = new FunctionInstanceInjector() {
+					@Override
+					public <T> T getInstance(Class<T> functionClass) throws Exception {
+						return functionClass.getDeclaredConstructor().newInstance();
+					}
+				};
+			}
+		}
+		finally {
+			Thread.currentThread().setContextClassLoader(prevContextClassLoader);
+		}
+		return functionInstanceInjector;
+	}
+
+	@Configuration
+	@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
+			@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
+	public static class MyMainConfig {
+
+		@Bean
+		public Function<String, String> uppercase() {
+			return message -> message.toUpperCase();
+		}
+	}
+
+	@Configuration
+	public static class MyAzureTestFunction {
+
+		@Autowired
+		private Function<String, String> uppercase;
+
+		@FunctionName("ditest")
+		public String execute(
+				@HttpTrigger(name = "req", methods = { HttpMethod.GET,
+						HttpMethod.POST }, authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage<Optional<String>> request,
+				ExecutionContext context) {
+
+			return uppercase.apply(request.getBody().get());
+		}
+	}
+}