Tighten up contract for SingleEntryFunctionRegistry

And add some tests. Fixes gh-250.

spring-cloud-function-deployer/src/main/java/org/springframework/cloud/function/deployer/FunctionCreatorConfiguration.java

@@ -35,7 +35,6 @@ import java.util.function.Function;
 import java.util.function.Supplier;
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import javax.annotation.PostConstruct;
@@ -218,9 +217,11 @@ class FunctionCreatorConfiguration {
 			Manifest manifest = getArchive().getManifest();
 			String mainClass = null;
 			if (manifest != null) {
-				String functionClass = manifest.getMainAttributes().getValue("Function-Class");
-				if (StringUtils.hasText(functionClass) && ObjectUtils.isEmpty(properties.getBean())) {
-					properties.setBean(new String[] {functionClass});
+				String functionClass = manifest.getMainAttributes()
+						.getValue("Function-Class");
+				if (StringUtils.hasText(functionClass)
+						&& ObjectUtils.isEmpty(properties.getBean())) {
+					properties.setBean(new String[] { functionClass });
 				}
 				mainClass = manifest.getMainAttributes().getValue("Start-Class");
 				if (mainClass == null
@@ -252,7 +253,7 @@ class FunctionCreatorConfiguration {
 				catch (MalformedURLException e) {
 					throw new IllegalStateException("Bad URL: " + archive, e);
 				}
-			}).collect(Collectors.toList()).toArray(new URL[0]);
+			}).toArray(URL[]::new);
 		}
 
 		private URL[] extractClasspath(String url) {
@@ -597,10 +598,13 @@ class FunctionCreatorConfiguration {
 		@Override
 		public Object postProcessAfterInitialization(Object bean, String beanName)
 				throws BeansException {
-			String name = FunctionProperties
-					.functionName(env.getProperty("function.bean", ""));
-			if (bean instanceof FunctionRegistry && name.contains("|")) {
-				bean = new SingleEntryFunctionRegistry((FunctionRegistry) bean, name);
+			if (bean instanceof FunctionRegistry) {
+				String name = FunctionProperties
+						.functionName(env.getProperty("function.bean", ""));
+				if (name.contains("|")) {
+					// A single composite function with an empty name
+					bean = new SingleEntryFunctionRegistry((FunctionRegistry) bean, name);
+				}
 			}
 			return bean;
 		}

spring-cloud-function-deployer/src/main/java/org/springframework/cloud/function/deployer/SingleEntryFunctionRegistry.java

@@ -20,6 +20,7 @@ import java.util.Set;
 
 import org.springframework.cloud.function.context.FunctionRegistration;
 import org.springframework.cloud.function.context.FunctionRegistry;
+import org.springframework.util.StringUtils;
 
 /**
  * @author Dave Syer
@@ -38,14 +39,18 @@ public class SingleEntryFunctionRegistry implements FunctionRegistry {
 
 	@Override
 	public <T> T lookup(Class<?> type, String name) {
-		return this.name.equals(name) ? this.delegate.lookup(type, name) : null;
+		if (StringUtils.isEmpty(name)) {
+			if (delegate.getNames(type).size() == 1) {
+				return delegate.lookup(type, delegate.getNames(type).iterator().next());
+			}
+			name = this.name;
+		}
+		return name.equals(this.name) ? delegate.lookup(type, name) : null;
 	}
 
 	@Override
 	public Set<String> getNames(Class<?> type) {
-		Set<String> names = this.delegate.getNames(type);
-		return names.contains(this.name) ? Collections.singleton(this.name)
-				: Collections.emptySet();
+		return Collections.singleton(this.name);
 	}
 
 	@Override

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

@@ -0,0 +1,76 @@
+/*
+ * 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.deployer;
+
+import java.util.function.Function;
+
+import org.junit.Test;
+
+import org.springframework.cloud.function.context.FunctionRegistration;
+import org.springframework.cloud.function.context.catalog.InMemoryFunctionCatalog;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Dave Syer
+ *
+ */
+public class SingleEntryFunctionRegistryTests {
+
+	private InMemoryFunctionCatalog delegate = new InMemoryFunctionCatalog();
+
+	@Test
+	public void named() {
+		delegate.register(new FunctionRegistration<Foos>(new Foos(), "foo"));
+		SingleEntryFunctionRegistry registry = new SingleEntryFunctionRegistry(delegate,
+				"foo");
+		assertThat((Foos) registry.lookup("foo")).isInstanceOf(Function.class);
+	}
+
+	@Test
+	public void other() {
+		delegate.register(new FunctionRegistration<Foos>(new Foos(), "foo"));
+		SingleEntryFunctionRegistry registry = new SingleEntryFunctionRegistry(delegate,
+				"foo");
+		assertThat((Foos) registry.lookup("bar")).isNull();
+	}
+
+	@Test
+	public void empty() {
+		delegate.register(new FunctionRegistration<Foos>(new Foos(), ""));
+		SingleEntryFunctionRegistry registry = new SingleEntryFunctionRegistry(delegate,
+				"");
+		assertThat((Foos) registry.lookup("")).isInstanceOf(Function.class);
+	}
+
+	@Test
+	public void anonymous() {
+		delegate.register(new FunctionRegistration<Foos>(new Foos(), "bar"));
+		SingleEntryFunctionRegistry registry = new SingleEntryFunctionRegistry(delegate,
+				"foo");
+		assertThat((Foos) registry.lookup("")).isInstanceOf(Function.class);
+	}
+
+	class Foos implements Function<String, String> {
+
+		@Override
+		public String apply(String t) {
+			return t.toUpperCase();
+		}
+
+	}
+
+}