tests/org.eclipse.jface.tests.databinding/src/org/eclipse/core/tests/databinding/observable/value/ComputedValueTest.java

/*******************************************************************************
 * Copyright (c) 2006, 2007 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *     Brad Reynolds - bug 116920
 *     Brad Reynolds - bug 164653
 *******************************************************************************/

package org.eclipse.core.tests.databinding.observable.value;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.eclipse.core.databinding.observable.value.ComputedValue;
import org.eclipse.core.databinding.observable.value.WritableValue;
import org.eclipse.jface.tests.databinding.AbstractDefaultRealmTestCase;
import org.junit.Test;

/**
 * @since 1.0
 *
 */
public class ComputedValueTest extends AbstractDefaultRealmTestCase {
    @Test
	public void testValueType() throws Exception {
        ComputedValue cv = new ComputedValue(Integer.TYPE) {
            @Override
			protected Object calculate() {
                return Integer.valueOf(42);
            }
        };
        assertEquals("value type should be the type that was set", Integer.TYPE, cv.getValueType());

        cv = new ComputedValue() {
            @Override
			protected Object calculate() {
                // TODO Auto-generated method stub
                return null;
            }
        };

        assertNull(cv.getValueType());
    }

    @Test
	public void test_getValue() throws Exception {
        ComputedValue cv = new ComputedValue() {
            @Override
			protected Object calculate() {
                return Integer.valueOf(42);
            }
        };
        assertEquals("Calculated value should be 42", Integer.valueOf(42), cv.getValue());
    }

    @Test
	public void testDependencyValueChange() throws Exception {
        final WritableValue value = new WritableValue(Integer.valueOf(42), Integer.TYPE);

        ComputedValue cv = new ComputedValue() {
            @Override
			protected Object calculate() {
                return value.getValue();
            }
        };

        assertEquals("calculated value should have been that of the writable value", value.getValue(), cv.getValue());

        value.setValue(Integer.valueOf(44));

        assertEquals("calculated value should have been that of the writable value", value.getValue(), cv.getValue());
    }

    private static class WritableValueExt extends WritableValue {
        public WritableValueExt(Object valueType, Object initialValue) {
            super(initialValue, valueType);
        }

        @Override
		public boolean hasListeners() {
            return super.hasListeners();
        }
    }

    @Test
	public void testHookAndUnhookDependantObservables() throws Exception {
        final List values = new ArrayList();

        ComputedValue cv = new ComputedValue() {
            @Override
			protected Object calculate() {
                int sum = 0;
                for (Iterator it = values.iterator(); it.hasNext();) {
                    WritableValue value = (WritableValue) it.next();
                    sum += ((Integer) value.getValue()).intValue();

                }

                return Integer.valueOf(sum);
            }
        };

        WritableValueExt value1 = new WritableValueExt(Integer.TYPE, Integer.valueOf(1));
        WritableValueExt value2 = new WritableValueExt(Integer.TYPE, Integer.valueOf(1));
        values.add(value1);
        values.add(value2);

        assertFalse(value1.hasListeners());
        assertFalse(value2.hasListeners());
        cv.getValue();
        assertTrue(value1.hasListeners());
        assertTrue(value2.hasListeners());

        //force the computed value to be stale
        value2.setValue(Integer.valueOf(2));
        //remove value2 from the values that are used to compute the value
        values.remove(value2);

        //force the value to be computed
        cv.getValue();
        assertEquals(Integer.valueOf(1), cv.getValue());
        assertTrue(value1.hasListeners());
        assertFalse("because value2 is not a part of the calculation the listeners should have been removed", value2.hasListeners());
    }

    @Test
	public void testSetValueUnsupportedOperationException() throws Exception {
        ComputedValue cv = new ComputedValue() {
            @Override
			protected Object calculate() {
                return null;
            }
        };

        try {
            cv.setValue(new Object());
            fail("exception should have been thrown");
        } catch (UnsupportedOperationException e) {
        }
    }
}