#311 More Generics fixes

spring-auto-restdocs-core/src/main/java/capital/scalable/restdocs/payload/AbstractJacksonFieldSnippet.java

@@ -7,9 +7,9 @@
  * 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.
@@ -90,27 +90,37 @@ protected FieldDescriptors createFieldDescriptors(Operation operation,
 
     protected Type firstGenericType(MethodParameter param) {
         Type type = param.getGenericParameterType();
-        if (type instanceof ParameterizedType) {
+        if(type instanceof TypeVariable) {
+            TypeVariable tv = (TypeVariable)type;
+            return findTypeFromTypeVariable(tv, param.getContainingClass());
+        } else if (type instanceof ParameterizedType) {
             ParameterizedType parameterizedType = (ParameterizedType) type;
             Type actualArgument = parameterizedType.getActualTypeArguments()[0];
             if(actualArgument instanceof Class) {
                 return actualArgument;
             } else if(actualArgument instanceof TypeVariable) {
                 TypeVariable typeVariable = (TypeVariable)actualArgument;
-                String variableName = typeVariable.getName();
-                Map<TypeVariable, Type> typeMap = GenericTypeResolver.getTypeVariableMap(param.getContainingClass());
-                for(TypeVariable tv : typeMap.keySet()) {
-                    if(StringUtils.equals(tv.getName(), variableName)) {
-                        return typeMap.get(tv);
-                    }
-                }
+                return findTypeFromTypeVariable(typeVariable, param.getContainingClass());
             }             
             return ((ParameterizedType) type).getActualTypeArguments()[0];
         } else {
             return Object.class;
         }
     }
 
+    protected Type findTypeFromTypeVariable(TypeVariable typeVariable, Class<?> clazz) {
+        Type defaultReturnValue = Object.class;
+
+        String variableName = typeVariable.getName();
+        Map<TypeVariable, Type> typeMap = GenericTypeResolver.getTypeVariableMap(clazz);
+        for(TypeVariable tv : typeMap.keySet()) {
+            if(StringUtils.equals(tv.getName(), variableName)) {
+                return typeMap.get(tv);
+            }
+        }
+        return defaultReturnValue;
+    }
+
     protected abstract Type getType(HandlerMethod method);
 
     protected abstract boolean shouldFailOnUndocumentedFields();

spring-auto-restdocs-core/src/main/java/capital/scalable/restdocs/payload/JacksonResponseFieldSnippet.java

@@ -7,9 +7,9 @@
  * 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.
@@ -25,6 +25,7 @@
 import java.lang.reflect.GenericArrayType;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
+import java.lang.reflect.TypeVariable;
 import java.util.Map;
 
 import capital.scalable.restdocs.jackson.FieldDescriptors;
@@ -83,6 +84,8 @@ protected Type getType(final HandlerMethod method) {
             }
         } else if (REACTOR_FLUX_CLASS.equals(returnType.getCanonicalName())) {
             return (GenericArrayType) () -> firstGenericType(method.getReturnType());
+        } else if (method.getReturnType().getGenericParameterType() instanceof TypeVariable) {
+            return firstGenericType(method.getReturnType());
         } else {
             return returnType;
         }

spring-auto-restdocs-core/src/test/java/capital/scalable/restdocs/payload/JacksonResponseFieldSnippetTest.java

@@ -433,7 +433,7 @@ public void comment() throws Exception {
     }
 
     @Test
-    public void genericSuperMethod() throws Exception{
+    public void genericSuperMethodCollection() throws Exception{
         HandlerMethod handlerMethod = createHandlerMethod("getItemsGeneric");
         mockFieldComment(Item.class, "field1", "A string");
         mockFieldComment(Item.class, "field2", "A decimal");
@@ -452,6 +452,25 @@ public void genericSuperMethod() throws Exception{
 
     }
 
+    @Test
+    public void genericSuperMethodSingleItem() throws Exception {
+        HandlerMethod handlerMethod = createHandlerMethod("getItemGeneric");
+        mockFieldComment(Item.class, "field1", "A string");
+        mockFieldComment(Item.class, "field2", "A decimal");
+
+        new JacksonResponseFieldSnippet().document(operationBuilder
+                .attribute(HandlerMethod.class.getName(), handlerMethod)
+                .attribute(ObjectMapper.class.getName(), mapper)
+                .attribute(JavadocReader.class.getName(), javadocReader)
+                .attribute(ConstraintReader.class.getName(), constraintReader)
+                .build());
+
+        assertThat(this.generatedSnippets.snippet(AUTO_RESPONSE_FIELDS)).is(
+                tableWithHeader("Path", "Type", "Optional", "Description")
+                        .row("field1", "String", "true", "A string.")
+                        .row("field2", "Decimal", "true", "A decimal."));
+    }
+
 
     private void mockConstraintMessage(Class<?> type, String fieldName, String comment) {
         when(constraintReader.getConstraintMessages(type, fieldName))
@@ -511,6 +530,10 @@ public static abstract class GenericTestResource<E> implements IGenericTestResou
         public List<E> getItemsGeneric() {
             return Collections.singletonList(createGeneric());
         }
+
+        public E getItemGeneric() {
+            return createGeneric();
+        }
     }
 
     // actual method responses do not matter, they are here just for the illustration