google3/third_party/java_src/junit/main/java/org/junit/runners/model/NoGenericTypeParametersValidator.java

package org.junit.runners.model;

import java.lang.reflect.GenericArrayType;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import java.util.List;

class NoGenericTypeParametersValidator {
    private final Method method;

    NoGenericTypeParametersValidator(Method method) {
        this.method = method;
    }

    void validate(List<Throwable> errors) {
        for (Type each : method.getGenericParameterTypes()) {
            validateNoTypeParameterOnType(each, errors);
        }
    }

    private void validateNoTypeParameterOnType(Type type, List<Throwable> errors) {
        if (type instanceof TypeVariable<?>) {
            errors.add(new Exception("Method " + method.getName()
                    + "() contains unresolved type variable " + type));
        } else if (type instanceof ParameterizedType) {
            validateNoTypeParameterOnParameterizedType((ParameterizedType) type, errors);
        } else if (type instanceof WildcardType) {
            validateNoTypeParameterOnWildcardType((WildcardType) type, errors);
        } else if (type instanceof GenericArrayType) {
            validateNoTypeParameterOnGenericArrayType((GenericArrayType) type, errors);
        }
    }

    private void validateNoTypeParameterOnParameterizedType(ParameterizedType parameterized,
            List<Throwable> errors) {
        for (Type each : parameterized.getActualTypeArguments()) {
            validateNoTypeParameterOnType(each, errors);
        }
    }

    private void validateNoTypeParameterOnWildcardType(WildcardType wildcard,
            List<Throwable> errors) {
        for (Type each : wildcard.getUpperBounds()) {
            validateNoTypeParameterOnType(each, errors);
        }
        for (Type each : wildcard.getLowerBounds()) {
            validateNoTypeParameterOnType(each, errors);
        }
    }

    private void validateNoTypeParameterOnGenericArrayType(
            GenericArrayType arrayType, List<Throwable> errors) {
        validateNoTypeParameterOnType(arrayType.getGenericComponentType(), errors);
    }
}