CalculatorTest.java

/*   Copyright 2012 Tim Garrett, Mothsoft LLC
 *
 *  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 com.mothsoft.alexis.domain;

import static org.junit.Assert.assertEquals;

import org.junit.Test;

public class CalculatorTest {

    private static final double MAX_ERROR = 0.00001;

    @Test
    public void testCalculatePercentChange() {
        assertEquals(0.0, Calculator.calculatePercentChange(0, 0, 100), MAX_ERROR);
        assertEquals(-0.10, Calculator.calculatePercentChange(100, 0, 1000), MAX_ERROR);
        assertEquals(0.20, Calculator.calculatePercentChange(-5, -4, 20), MAX_ERROR);
        assertEquals(-0.25, Calculator.calculatePercentChange(-4, -5, 20), MAX_ERROR);
        assertEquals(0, Calculator.calculatePercentChange(3, 3, 100), MAX_ERROR);
        assertEquals(-0.03, Calculator.calculatePercentChange(3, 0, 100), MAX_ERROR);
        assertEquals(0.03, Calculator.calculatePercentChange(0, 3, 100), MAX_ERROR);
        assertEquals(3.66666666, Calculator.calculatePercentChange(-3, 8, 100), MAX_ERROR);
        assertEquals(-0.01407837, Calculator.calculatePercentChange(137.8, 135.86, 1000), MAX_ERROR);
        assertEquals(0.01427940, Calculator.calculatePercentChange(135.86, 137.8, 1000), MAX_ERROR);
    }
}