ExpressionBaseTest.java

/*
Copyright (c) 2008 Arno Haase, Andr� Arnold.
All rights reserved. This program and the accompanying materials
are made available under the terms of the Eclipse Public License v1.0
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/epl-v10.html

Contributors:
    Arno Haase - initial API and implementation
    Andr� Arnold
 */
package org.eclipse.xtend.backend.common;

import static org.eclipse.xtend.backend.testhelpers.BackendTestHelper.createEmptyExecutionContext;
import static org.eclipse.xtend.backend.testhelpers.BackendTestHelper.createLiteral;
import static org.eclipse.xtend.backend.testhelpers.BackendTestHelper.createSourcePos;
import static org.junit.Assert.assertEquals;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.junit.Before;
import org.junit.Test;


/**
 * 
 * @author Arno Haase (http://www.haase-consulting.com)
 * @author Andr� Arnold
 */
public class ExpressionBaseTest {
    private final List<String> _log = new ArrayList<String> ();
    
    @Before
    public void init () {
        _log.clear ();
    }
    
    private class TestingExecutionListener implements ExecutionListener {
        private final String _id;
        private final Object _vetoValue;
        
        public TestingExecutionListener (String id, Object vetoValue) {
            _id = id;
            _vetoValue = vetoValue;
        }

        public void preExecute (ExecutionContext ctx, ExpressionBase originator) throws EvaluationVetoException {
            _log.add("pre" + _id);
            if (_vetoValue != null)
                throw new EvaluationVetoException (_vetoValue);
        }
        
        public void postExecute (Object result, ExecutionContext ctx, ExpressionBase originator) {
            _log.add ("post" + _id);
        }
    }
    
    
    
    @Test
    public void testVeto () {
        final ExpressionBase expr = new ExpressionBase (createSourcePos()) {

            @Override
            protected Object evaluateInternal (ExecutionContext ctx) {
                ExpressionBaseTest.this._log.add ("evaluated");
                return null;
            }
        };
        
        expr.registerExecutionListener (new TestingExecutionListener ("First", "veto1"));
        expr.registerExecutionListener (new TestingExecutionListener ("Second", "veto2"));
        
        assertEquals ("veto1", expr.evaluate (createEmptyExecutionContext()));
        assertEquals (Arrays.asList ("preFirst"), _log);
        
    }
    
    
    @Test 
    public void testExecutionListener () {
        final ExpressionBase expr = createLiteral ("a");

        expr.registerExecutionListener (new TestingExecutionListener ("First", null));
        expr.registerExecutionListener (new TestingExecutionListener ("Second", null));
        
        expr.evaluate (createEmptyExecutionContext());
        
        assertEquals (Arrays.asList ("preFirst", "preSecond", "postSecond", "postFirst"), _log);
    }
}