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1   /*
2    * Copyright 2003-2006 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.commons.jexl.junit;
18  
19  import java.util.HashMap;
20  import java.util.Map;
21  
22  import junit.framework.Assert;
23  
24  import org.apache.commons.jexl.Expression;
25  import org.apache.commons.jexl.ExpressionFactory;
26  import org.apache.commons.jexl.JexlContext;
27  import org.apache.commons.jexl.JexlHelper;
28  
29  /***
30   * A utility class for performing JUnit based assertions using Jexl
31   * expressions. This class can make it easier to do unit tests using
32   * Jexl navigation expressions.
33   *
34   * @since 1.0
35   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
36   * @version $Revision: 398153 $
37   */
38  public class Asserter extends Assert {
39  
40      /*** variables used during asserts. */
41      private final Map variables = new HashMap();
42      /*** context to use during asserts. */
43      private final JexlContext context = JexlHelper.createContext();
44  
45      /***
46       * 
47       * Create an asserter.
48       */
49      public Asserter() {
50  
51      }
52  
53      /***
54       * This constructor will register the given variableValue as the
55       * "this" variable.
56       * 
57       * @param variableValue 'this'.
58       */
59      public Asserter(Object variableValue) {
60          setVariable("this", variableValue);
61      }
62  
63      /***
64       * Performs an assertion that the value of the given Jexl expression 
65       * evaluates to the given expected value.
66       * 
67       * @param expression is the Jexl expression to evaluate
68       * @param expected is the expected value of the expression
69       * @throws Exception if the expression could not be evaluationed or an assertion
70       * fails
71       */
72      public void assertExpression(String expression, Object expected) throws Exception {
73          Expression exp = ExpressionFactory.createExpression(expression);
74  
75          context.setVars(variables);
76          Object value = exp.evaluate(context);
77  
78          assertEquals("expression: " + expression, expected, value);
79      }
80  
81      /***
82       * Puts a variable of a certain name in the context so that it can be used from
83       * assertion expressions.
84       * 
85       * @param name variable name
86       * @param value variable value
87       */
88      public void setVariable(String name, Object value) {
89          variables.put(name, value);
90      }
91  
92  }