//=============================================================================
// Copyright 2006-2010 Daniel W. Dyer
//
// 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 org.uncommons.watchmaker.examples.geneticprogramming;
import org.testng.annotations.Test;
/**
* Simple unit test for the {@link Multiplication} node type.
* @author Daniel Dyer
*/
public class MultiplicationTest
{
@Test
public void testEvaluation()
{
Node node = new Multiplication(new Constant(5), new Constant(2));
double value = node.evaluate(new double[0]);
assert value == 10 : "Wrong result: " + value;
}
@Test
public void testStringRepresentation()
{
Node node = new Multiplication(new Constant(5), new Parameter(0));
assert node.print().equals("(5.0 * arg0)") : "Wrong string representation: " + node.print();
}
/**
* If the arguments to the multiply function are both constants then the multiplication node
* should be replaced by a constant node containing the evaluation of this product.
*/
@Test
public void testSimplifyConstants()
{
Node node = new Multiplication(new Constant(3), new Constant(4));
Node simplified = node.simplify();
assert simplified instanceof Constant
: "Simplified node should be Constant, is " + simplified.getClass().getSimpleName();
assert simplified.evaluate(BinaryNode.NO_ARGS) == node.evaluate(BinaryNode.NO_ARGS) : "Simplified answer differs.";
assert simplified.evaluate(BinaryNode.NO_ARGS) == 12;
}
/**
* If the lefthand argument is zero, the result will always be zero regardless of the righthand
* argument.
*/
@Test
public void testSimplifyMultiplyZero()
{
Node node = new Multiplication(new Constant(0), new Parameter(0));
Node simplified = node.simplify();
assert simplified instanceof Constant
: "Simplified node should be Constant, is " + simplified.getClass().getSimpleName();
double[] args = new double[]{5}; // Provides a value for the parameter nodes.
assert simplified.evaluate(args) == node.evaluate(args) : "Simplified answer differs.";
assert simplified.evaluate(BinaryNode.NO_ARGS) == 0;
}
/**
* If the righthand argument is zero, the result will always be zero regardless of the lefthand
* argument.
*/
@Test
public void testSimplifyMultiplyByZero()
{
Node node = new Multiplication(new Parameter(0), new Constant(0));
Node simplified = node.simplify();
assert simplified instanceof Constant
: "Simplified node should be Constant, is " + simplified.getClass().getSimpleName();
double[] args = new double[]{5}; // Provides a value for the parameter nodes.
assert simplified.evaluate(args) == node.evaluate(args) : "Simplified answer differs.";
assert simplified.evaluate(BinaryNode.NO_ARGS) == 0;
}
/**
* If the lefthand argument is one, the result can be reduced to the righthand argument.
*/
@Test
public void testSimplifyMultiplyOne()
{
Node node = new Multiplication(new Constant(1), new Parameter(0));
Node simplified = node.simplify();
assert simplified instanceof Parameter
: "Simplified node should be Parameter, is " + simplified.getClass().getSimpleName();
double[] args = new double[]{5}; // Provides a value for the parameter nodes.
assert simplified.evaluate(args) == node.evaluate(args) : "Simplified answer differs.";
assert simplified.evaluate(args) == 5;
}
/**
* If the righthand argument is one, the result can be reduced to the lefthand argument.
*/
@Test
public void testSimplifyMultiplyByOne()
{
Node node = new Multiplication(new Parameter(0), new Constant(1));
Node simplified = node.simplify();
assert simplified instanceof Parameter
: "Simplified node should be Parameter, is " + simplified.getClass().getSimpleName();
double[] args = new double[]{5}; // Provides a value for the parameter nodes.
assert simplified.evaluate(args) == node.evaluate(args) : "Simplified answer differs.";
assert simplified.evaluate(args) == 5;
}
/**
* Test that simplification doesn't cause any problems when the expression is already as simple
* as possible.
*/
@Test
public void testSimplifySimplest()
{
Node node = new Multiplication(new Parameter(0), new Constant(2));
Node simplified = node.simplify();
assert simplified == node : "Expression should not have been changed.";
}
/**
* Make sure that sub-nodes are simplified.
*/
@Test
public void testSimplifySubNode()
{
Node node = new Multiplication(new Parameter(0),
new Multiplication(new Constant(3), new Constant(2)));
Node simplified = node.simplify();
assert simplified instanceof Multiplication
: "Simplified node should be Multiplication, is " + simplified.getClass().getSimpleName();
double[] args = new double[]{5}; // Provides a value for the parameter nodes.
assert simplified.evaluate(args) == node.evaluate(args) : "Simplified answer differs.";
assert simplified.countNodes() < node.countNodes() : "Should be fewer nodes after simplification.";
}
}