Add support for detecting FunctionRegistration or Function

User can now provide a Function or an ApplicationInitializer. Also
the initializer can create a FunctionRegistration with the handler
name instead of a bean with the handler name. Better control of
input and output types that way.

Fixes gh-231

spring-cloud-function-deployer/src/test/java/org/springframework/cloud/function/deployer/FunctionCreatorConfigurationTests.java

@@ -21,7 +21,6 @@ import java.util.function.Supplier;
 
 import org.junit.Assume;
 import org.junit.BeforeClass;
-import org.junit.Ignore;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -97,13 +96,45 @@ public abstract class FunctionCreatorConfigurationTests {
 	@EnableAutoConfiguration
 	@TestPropertySource(properties = {
 			"function.location=app:classpath,file:target/test-classes,file:target/test-classes/app",
-			"function.bean=myDoubler",
+			"function.bean=doubler",
 			"function.main=org.springframework.cloud.function.test.FunctionRegistrar" })
 	public static class SingleFunctionWithRegistrarTests
 			extends FunctionCreatorConfigurationTests {
 
 		@Test
-		@Ignore // related to boot 2.1 no bean override change
+		public void testDouble() {
+			Function<Flux<Integer>, Flux<Integer>> function = catalog
+					.lookup(Function.class, "function0");
+			assertThat(function.apply(Flux.just(2)).blockFirst()).isEqualTo(4);
+		}
+
+	}
+
+	@EnableAutoConfiguration
+	@TestPropertySource(properties = {
+			"function.location=app:classpath,file:target/test-classes,file:target/test-classes/app",
+			"function.bean=frenchizer",
+			"function.main=org.springframework.cloud.function.test.FunctionRegistrar" })
+	public static class SingleFunctionWithRegistrarAndRegistrationTests
+			extends FunctionCreatorConfigurationTests {
+
+		@Test
+		public void testFrenchize() {
+			Function<Flux<Integer>, Flux<String>> function = catalog
+					.lookup(Function.class, "function0");
+			assertThat(function.apply(Flux.just(2)).blockFirst()).isEqualTo("deux");
+		}
+	}
+
+	@EnableAutoConfiguration
+	@TestPropertySource(properties = {
+			"function.location=app:classpath,file:target/test-classes,file:target/test-classes/app",
+			"function.bean=myDoubler",
+			"function.main=org.springframework.cloud.function.test.FunctionInitializer" })
+	public static class SingleFunctionWithInitializerTests
+			extends FunctionCreatorConfigurationTests {
+
+		@Test
 		public void testDouble() {
 			Function<Flux<Integer>, Flux<Integer>> function = catalog
 					.lookup(Function.class, "function0");

spring-cloud-function-deployer/src/test/java/org/springframework/cloud/function/test/FunctionInitializer.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 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.test;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.cloud.function.context.FunctionalSpringApplication;
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.support.GenericApplicationContext;
+
+/**
+ * @author Dave Syer
+ */
+public class FunctionInitializer
+		implements ApplicationContextInitializer<GenericApplicationContext> {
+
+	@Bean
+	public Doubler myDoubler() {
+		return new Doubler();
+	}
+
+	@Bean
+	public Frenchizer myFrenchizer() {
+		return new Frenchizer();
+	}
+
+	public static void main(String[] args) throws Exception {
+		SpringApplication application = new FunctionalSpringApplication(
+				FunctionInitializer.class);
+		application.run(args);
+	}
+
+	@Override
+	public void initialize(GenericApplicationContext context) {
+		// TODO: support for FunctionRegistration
+		context.registerBean("myDoubler", Doubler.class, () -> myDoubler());
+		context.registerBean("myFrenchizer", Frenchizer.class, () -> myFrenchizer());
+	}
+}

spring-cloud-function-deployer/src/test/java/org/springframework/cloud/function/test/FunctionRegistrar.java

@@ -16,10 +16,10 @@
 
 package org.springframework.cloud.function.test;
 
-import java.util.Collections;
-
 import org.springframework.boot.SpringApplication;
-import org.springframework.context.ApplicationContext;
+import org.springframework.cloud.function.context.FunctionRegistration;
+import org.springframework.cloud.function.context.FunctionType;
+import org.springframework.cloud.function.context.FunctionalSpringApplication;
 import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.support.GenericApplicationContext;
@@ -41,21 +41,21 @@ public class FunctionRegistrar
 	}
 
 	public static void main(String[] args) throws Exception {
-		SpringApplication application = new SpringApplication(Object.class) {
-			@Override
-			protected void load(ApplicationContext context, Object[] sources) {
-			}
-		};
-		application.addInitializers(new FunctionRegistrar());
-		application.setDefaultProperties(
-				Collections.singletonMap("spring.functional.enabled", "true"));
+		SpringApplication application = new FunctionalSpringApplication(
+				FunctionRegistrar.class);
 		application.run(args);
 	}
 
 	@Override
 	public void initialize(GenericApplicationContext context) {
-		// TODO: support for FunctionRegistration
-		context.registerBean("myDoubler", Doubler.class, () -> myDoubler());
-		context.registerBean("myFrenchizer", Frenchizer.class, () -> myFrenchizer());
+		context.registerBean("theDoubler", FunctionRegistration.class,
+				() -> new FunctionRegistration<>(myDoubler(), "doubler")
+						.type(FunctionType.of((Doubler.class))));
+		context.registerBean("frenchizer", FunctionRegistration.class, () -> {
+			Frenchizer function = myFrenchizer();
+			function.init();
+			return new FunctionRegistration<>(function, "theFrenchizer")
+					.type(FunctionType.of((Frenchizer.class)));
+		});
 	}
 }