Add "wrapper" type methods to FunctionInspector

These can be used to more reliably discover whether the user
has declared a function with flux types or "bare" POJOs. They
then pave the way to supporting single valued types in a special
way.

Also consolidate and simplify the logic in FunctionInspector

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

@@ -30,9 +30,12 @@ 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.cloud.function.test.GenericFunction;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -68,6 +71,34 @@ public class ContextFunctionCatalogAutoConfigurationTests {
 		assertThat(context.getBean("function")).isInstanceOf(Function.class);
 		assertThat(catalog.lookupFunction("function")).isInstanceOf(Function.class);
 		assertThat(inspector.getInputType("function")).isAssignableFrom(Map.class);
+		assertThat(inspector.getInputWrapper("function")).isAssignableFrom(Map.class);
+	}
+
+	@Test
+	public void genericFluxFunction() {
+		create(GenericFluxConfiguration.class);
+		assertThat(context.getBean("function")).isInstanceOf(Function.class);
+		assertThat(catalog.lookupFunction("function")).isInstanceOf(Function.class);
+		assertThat(inspector.getInputType("function")).isAssignableFrom(Map.class);
+		assertThat(inspector.getInputWrapper("function")).isAssignableFrom(Flux.class);
+	}
+
+	@Test
+	public void externalFunction() {
+		create(ExternalConfiguration.class);
+		assertThat(context.getBean("function")).isInstanceOf(Function.class);
+		assertThat(catalog.lookupFunction("function")).isInstanceOf(Function.class);
+		assertThat(inspector.getInputType("function")).isAssignableFrom(Map.class);
+		assertThat(inspector.getInputWrapper("function")).isAssignableFrom(Map.class);
+	}
+
+	@Test
+	public void componentScanFunction() {
+		create(ComponentScanConfiguration.class);
+		assertThat(context.getBean("function")).isInstanceOf(Function.class);
+		assertThat(catalog.lookupFunction("function")).isInstanceOf(Function.class);
+		assertThat(inspector.getInputType("function")).isAssignableFrom(Map.class);
+		assertThat(inspector.getInputWrapper("function")).isAssignableFrom(Map.class);
 	}
 
 	@Test
@@ -149,6 +180,28 @@ public class ContextFunctionCatalogAutoConfigurationTests {
 		}
 	}
 
+	@EnableAutoConfiguration
+	@Configuration
+	@Import(GenericFunction.class)
+	protected static class ExternalConfiguration {
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	@ComponentScan(basePackageClasses=GenericFunction.class)
+	protected static class ComponentScanConfiguration {
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	protected static class GenericFluxConfiguration {
+		@Bean
+		public Function<Flux<Map<String, String>>, Flux<Map<String, String>>> function() {
+			return flux -> flux.map(m -> m.entrySet().stream().collect(Collectors
+					.toMap(e -> e.getKey(), e -> e.getValue().toString().toUpperCase())));
+		}
+	}
+
 	@EnableAutoConfiguration
 	@Configuration
 	protected static class QualifiedConfiguration {
@@ -184,3 +237,4 @@ public class ContextFunctionCatalogAutoConfigurationTests {
 	}
 
 }
+

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

@@ -0,0 +1,38 @@
+/*
+ * 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.test;
+
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * @author Dave Syer
+ *
+ */
+@Configuration
+public class GenericFunction {
+	@Bean
+	public Function<Map<String, String>, Map<String, String>> function() {
+		return m -> m.entrySet().stream().collect(Collectors.toMap(e -> e.getKey(),
+				e -> e.getValue().toString().toUpperCase()));
+	}
+}
+