ValuePredicate.java

/**
 * Copyright 2011-2017 Asakusa Framework Team.
 *
 * 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 com.asakusafw.testdriver.rule;

/**
 * 2-arity predicate object.
 * @param <T> type of value
 * @since 0.2.0
 */
public interface ValuePredicate<T> {

    /**
     * Returns {@code true} iff both values satisfy this predicate.
     * @param expected the expected value (nullable)
     * @param actual the actual value (nullable)
     * @return {@code true} iff both values satisfy this predicate, {@code false} otherwise.
     * @throws IllegalArgumentException if failed to calculate its satisfaction
     */
    boolean accepts(T expected, T actual);

    /**
     * Returns an expected value as readable text.
     * @param expected the expected value (nullable)
     * @param actual the actual value (nullable)
     * @return readable text, or {@code null} if is always/never expected
     */
    String describeExpected(T expected, T actual);
}