Add support for explicit FunctionRegistration

A bean of type FunctionRegistration registers the function with
user-specified name and other properties, rather than relying on the
bean name.

Alternatively, function catalog keys can be specified as a
@Qualifier, which will be used instead of the bean name if
no registration is found.

spring-cloud-function-context/test/java/org/springframework/cloud/function/context/ContextFunctionCatalogAutoConfigurationTests.java

@@ -0,0 +1,159 @@
+/*
+ * Copyright 2012-2015 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.context;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import org.junit.After;
+import org.junit.Test;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import reactor.core.publisher.Flux;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public class ContextFunctionCatalogAutoConfigurationTests {
+
+	private ConfigurableApplicationContext context;
+	private InMemoryFunctionCatalog catalog;
+
+	@After
+	public void close() {
+		if (context != null) {
+			context.close();
+		}
+	}
+
+	@Test
+	public void simpleFunction() {
+		create(SimpleConfiguration.class);
+		assertThat(context.getBean("function")).isInstanceOf(Function.class);
+		assertThat(catalog.lookupFunction("function")).isInstanceOf(Function.class);
+	}
+
+	@Test
+	public void simpleSupplier() {
+		create(SimpleConfiguration.class);
+		assertThat(context.getBean("supplier")).isInstanceOf(Supplier.class);
+		Supplier<Flux<String>> supplier = catalog.lookupSupplier("supplier");
+		assertThat(supplier.get().blockFirst()).isEqualTo("hello");
+	}
+
+	@Test
+	public void simpleConsumer() {
+		create(SimpleConfiguration.class);
+		assertThat(context.getBean("consumer")).isInstanceOf(Consumer.class);
+		Consumer<Flux<String>> consumer = catalog.lookupConsumer("consumer");
+		consumer.accept(Flux.just("foo", "bar"));
+		assertThat(context.getBean(SimpleConfiguration.class).list).hasSize(2);
+	}
+
+	@Test
+	public void qualifiedBean() {
+		create(QualifiedConfiguration.class);
+		assertThat(context.getBean("function")).isInstanceOf(Function.class);
+		assertThat(catalog.lookupFunction("function")).isNull();
+		assertThat(catalog.lookupFunction("other")).isInstanceOf(Function.class);
+	}
+
+	@Test
+	public void aliasBean() {
+		create(AliasConfiguration.class);
+		assertThat(context.getBean("function")).isInstanceOf(Function.class);
+		assertThat(catalog.lookupFunction("function")).isNotNull();
+		assertThat(catalog.lookupFunction("other")).isInstanceOf(Function.class);
+	}
+
+	@Test
+	public void registrationBean() {
+		create(RegistrationConfiguration.class);
+		assertThat(context.getBean("function")).isInstanceOf(Function.class);
+		assertThat(catalog.lookupFunction("function")).isNull();
+		assertThat(catalog.lookupFunction("registration")).isNull();
+		assertThat(catalog.lookupFunction("other")).isInstanceOf(Function.class);
+	}
+
+	private void create(Class<?>... types) {
+		context = new SpringApplicationBuilder((Object[]) types).run();
+		catalog = context.getBean(InMemoryFunctionCatalog.class);
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	protected static class SimpleConfiguration {
+		private List<String> list = new ArrayList<>();
+		@Bean
+		public Function<String, String> function() {
+			return value -> value.toUpperCase();
+		}
+		@Bean
+		public Supplier<String> supplier() {
+			return () -> "hello";
+		}
+		@Bean
+		public Consumer<String> consumer() {
+			return value -> list.add(value);
+		}
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	protected static class QualifiedConfiguration {
+		@Bean
+		@Qualifier("other")
+		public Function<String, String> function() {
+			return value -> value.toUpperCase();
+		}
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	protected static class AliasConfiguration {
+		@Bean({"function", "other"})
+		public Function<String, String> function() {
+			return value -> value.toUpperCase();
+		}
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	protected static class RegistrationConfiguration {
+		@Bean
+		public FunctionRegistration<Function<String, String>> registration() {
+			return new FunctionRegistration<Function<String, String>>(function()).name("other");
+		}
+		@Bean
+		public Function<String, String> function() {
+			return value -> value.toUpperCase();
+		}
+	}
+
+}