Add support for application type Function in Azure

See #215

spring-cloud-function-adapters/spring-cloud-function-adapter-azure/src/main/java/org/springframework/cloud/function/adapter/azure/AzureSpringFunctionInitializer.java

@@ -38,10 +38,13 @@ import org.springframework.boot.SpringApplication;
 import org.springframework.boot.WebApplicationType;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.cloud.function.context.FunctionCatalog;
+import org.springframework.cloud.function.context.FunctionRegistration;
+import org.springframework.cloud.function.context.FunctionType;
 import org.springframework.cloud.function.context.catalog.FunctionInspector;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -135,22 +138,39 @@ public class AzureSpringFunctionInitializer implements Closeable {
 	}
 
 	private SpringApplication springApplication() {
-		ApplicationContextInitializer<?> initializer = null;
+		ApplicationContextInitializer<GenericApplicationContext> initializer = null;
 		Class<?> sourceClass = configurationClass;
 		if (ApplicationContextInitializer.class.isAssignableFrom(sourceClass)) {
-			initializer = BeanUtils.instantiateClass(configurationClass, ApplicationContextInitializer.class);
+			@SuppressWarnings("unchecked")
+			ApplicationContextInitializer<GenericApplicationContext> instance = BeanUtils
+					.instantiateClass(configurationClass,
+							ApplicationContextInitializer.class);
+			initializer = instance;
+			sourceClass = Object.class;
+		}
+		else if (Function.class.isAssignableFrom(sourceClass)) {
+			@SuppressWarnings("unchecked")
+			final Class<Function<?, ?>> type = (Class<Function<?, ?>>) sourceClass;
+			initializer = context -> {
+				context.registerBean(FunctionRegistration.class,
+						() -> new FunctionRegistration<>(
+								context.getAutowireCapableBeanFactory().createBean(type))
+										.type(FunctionType.of(type)));
+			};
 			sourceClass = Object.class;
 		}
 		SpringApplication application;
-		if (initializer!=null) {
+		if (initializer != null) {
 			application = new SpringApplication(sourceClass) {
 				@Override
 				protected void load(ApplicationContext context, Object[] sources) {
 				}
 			};
 			application.addInitializers(initializer);
-			application.setDefaultProperties(Collections.singletonMap("spring.functional.enabled", "true"));
-		} else {
+			application.setDefaultProperties(
+					Collections.singletonMap("spring.functional.enabled", "true"));
+		}
+		else {
 			application = new SpringApplication(sourceClass);
 		}
 		application.setWebApplicationType(WebApplicationType.NONE);
@@ -240,4 +260,16 @@ public class AzureSpringFunctionInitializer implements Closeable {
 		}
 		return null;
 	}
+
+	public Function<Publisher<?>, Publisher<?>> getFunction() {
+		return function;
+	}
+
+	public FunctionCatalog getCatalog() {
+		return catalog;
+	}
+
+	public FunctionInspector getInspector() {
+		return inspector;
+	}
 }

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

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2016-2017 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
+ *
+ *      http://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;
+
+import java.io.IOException;
+import java.util.function.Function;
+
+import org.junit.After;
+import org.junit.Test;
+
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.cloud.function.context.FunctionRegistration;
+import org.springframework.cloud.function.context.FunctionType;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.support.GenericApplicationContext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import reactor.core.publisher.Flux;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public class AzureSpringFunctionInitializerTests {
+
+	private AzureSpringFunctionInitializer handler = null;
+
+	<I, O> AzureSpringFunctionInitializer handler(Class<?> config) {
+		AzureSpringFunctionInitializer handler = new AzureSpringFunctionInitializer(
+				config);
+		this.handler = handler;
+		return handler;
+	}
+
+	@After
+	public void close() throws IOException {
+		if (handler != null)
+			handler.close();
+	}
+
+	@Test
+	public void bareConfig() {
+		AzureSpringFunctionInitializer handler = handler(BareConfig.class);
+		handler.initialize(new TestExecutionContext("uppercase"));
+		Bar bar = (Bar) Flux.from(handler.getFunction().apply(Flux.just(new Foo("bar"))))
+				.blockFirst();
+		assertThat(bar.getValue()).isEqualTo("BAR");
+	}
+
+	@Test
+	public void initializer() {
+		AzureSpringFunctionInitializer handler = handler(InitializerConfig.class);
+		handler.initialize(new TestExecutionContext("uppercase"));
+		Bar bar = (Bar) Flux.from(handler.getFunction().apply(Flux.just(new Foo("bar"))))
+				.blockFirst();
+		assertThat(bar.getValue()).isEqualTo("BAR");
+	}
+
+	@Test
+	public void function() {
+		AzureSpringFunctionInitializer handler = handler(FunctionConfig.class);
+		handler.initialize(new TestExecutionContext("uppercase"));
+		Bar bar = (Bar) Flux.from(handler.getFunction().apply(Flux.just(new Foo("bar"))))
+				.blockFirst();
+		assertThat(bar.getValue()).isEqualTo("BAR");
+	}
+
+	@SpringBootConfiguration
+	@EnableAutoConfiguration
+	protected static class BareConfig {
+		@Bean
+		public Function<Foo, Bar> function() {
+			return foo -> new Bar(foo.getValue().toUpperCase());
+		}
+	}
+
+	@SpringBootConfiguration
+	protected static class FunctionConfig implements Function<Foo, Bar> {
+		@Override
+		public Bar apply(Foo foo) {
+			return new Bar(foo.getValue().toUpperCase());
+		}
+	}
+
+	@SpringBootConfiguration
+	protected static class InitializerConfig
+			implements ApplicationContextInitializer<GenericApplicationContext> {
+
+		public Function<Foo, Bar> function() {
+			return foo -> new Bar(foo.getValue().toUpperCase());
+		}
+
+		@Override
+		public void initialize(GenericApplicationContext context) {
+			context.registerBean(FunctionRegistration.class,
+					() -> new FunctionRegistration<Function<Foo, Bar>>(function(),
+							"uppercase")
+									.type(FunctionType.from(Foo.class).to(Bar.class)));
+		}
+	}
+}