How to create a TypeMirror instance

I have an AnnotationProcessor that reads spring webmvc annotations and generates code based on what it finds.

The code works fine, but I need to figure out how to unit test a method that takes javax.lang.model.type.TypeMirror

as an argument and returns its representation of a String type, including generics (for example java.util.Map<java.lang.String, java.util.List<java.lang.String>>

- an example of what it would return if I passed TypeMirror

in representing a Map<String, List<String>>

as an argument.

So, to unit test this method (I was basing my code on this answer: Getting the qualified class name of a generic type with a Java 6 annotation handler ) I would like to either mock or create a TypeMirror during unit testing.

In my actual code I get TypeMirror

I need to use VariableElement.asType()

, but running the debugger leads me to conclude that the actual implementation of VariableElement is the main Java class and not part of the api: http://www.docjar.com/docs/api/com/sun/ tools / javac / code / Symbol $ VarSymbol.html

And TypeMirror impl is, similarly buried in the non-public part of the jdk: http://www.docjar.com/docs/api/com/sun/tools/javac/code/Type $ ClassType.html

I would rather not instantiate java's internal types - what's the "correct" way to instantiate TypeMirror

(or VariableElement

)? Has anyone mocked where they could give me an example?

This is the method I want to unit test:

private void typeToString(final TypeMirror type, final StringBuilder result,
                          final char innerClassSeparator) {
    type.accept(new SimpleTypeVisitor7<Void, Void>() {
        @Override
        public Void visitDeclared(DeclaredType declaredType, Void v) {
            TypeElement typeElement = (TypeElement) declaredType.asElement();
            String rawType = rawTypeToString(typeElement, innerClassSeparator);
            result.append(Util.getUnqualifiedClassName(rawType));
            //java.lang.* is auto-included by the compiler for all classes
            if (!rawType.startsWith("java.lang")) {
                importTypes.add(rawType);
            }
            List<? extends TypeMirror> typeArguments = declaredType.getTypeArguments();
            if (!typeArguments.isEmpty()) {
                result.append("<");
                for (int i = 0; i < typeArguments.size(); i++) {
                    if (i != 0) {
                        result.append(", ");
                    }
                    typeToString(typeArguments.get(i), result, innerClassSeparator);
                }
                result.append(">");
            }
            return null;
        }

        @Override
        public Void visitPrimitive(PrimitiveType primitiveType, Void v) {
            result.append(box((PrimitiveType) type).getName());
            return null;
        }

        @Override
        public Void visitArray(ArrayType arrayType, Void v) {
            TypeMirror type = arrayType.getComponentType();
            if (type instanceof PrimitiveType) {
                result.append(type.toString()); // Don't box, since this is an array.
            } else {
                typeToString(arrayType.getComponentType(), result, innerClassSeparator);
            }
            result.append("[]");
            return null;
        }

        @Override
        public Void visitTypeVariable(TypeVariable typeVariable, Void v) {
            result.append(typeVariable.asElement().getSimpleName());
            return null;
        }

        @Override
        public Void visitError(ErrorType errorType, Void v) {
            // Error type found, a type may not yet have been generated, but we need the type
            // so we can generate the correct code in anticipation of the type being available
            // to the compiler.

            // Paramterized types which don't exist are returned as an error type whose name is "<any>"
            if ("<any>".equals(errorType.toString())) {
                throw new CodeGenerationIncompleteException(
                        "Type reported as <any> is likely a not-yet generated parameterized type.");
            }
            result.append(errorType.toString());
            return null;
        }

        @Override
        protected Void defaultAction(TypeMirror typeMirror, Void v) {
            result.append("void");
            return null;
        }
    }, null);
}