COMMONS_JEXL_2_0/src/test/java/org/apache/commons/jexl2/junit/Asserter.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.jexl2.junit;

import java.util.HashMap;
import java.util.Map;

import junit.framework.Assert;

import org.apache.commons.jexl2.Expression;
import org.apache.commons.jexl2.JexlContext;
import org.apache.commons.jexl2.MapContext;
import org.apache.commons.jexl2.JexlEngine;

/**
 * A utility class for performing JUnit based assertions using Jexl
 * expressions. This class can make it easier to do unit tests using
 * Jexl navigation expressions.
 *
 * @since 1.0
 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
 * @version $Revision$
 */
public class Asserter extends Assert {
    /** variables used during asserts. */
    private final Map<String, Object> variables = new HashMap<String, Object>();
    /** context to use during asserts. */
    private final JexlContext context = new MapContext(variables);

    /** Jexl engine to use during Asserts. */
    private final JexlEngine engine;

    /**
     * 
     * Create an asserter.
     */
    public Asserter(JexlEngine jexl) {
        engine = jexl;
    }


    /**
     * Performs an assertion that the value of the given Jexl expression 
     * evaluates to the given expected value.
     * 
     * @param expression is the Jexl expression to evaluate
     * @param expected is the expected value of the expression
     * @throws Exception if the expression could not be evaluationed or an assertion
     * fails
     */
    public void assertExpression(String expression, Object expected) throws Exception {
        Expression exp = engine.createExpression(expression);
        Object value = exp.evaluate(context);

        assertEquals("expression: " + expression, expected, value);
    }

    /**
     * Puts a variable of a certain name in the context so that it can be used from
     * assertion expressions.
     * 
     * @param name variable name
     * @param value variable value
     */
    public void setVariable(String name, Object value) {
        variables.put(name, value);
    }

}