jUnit-Calculator.zip_JUnit_JUnit加减乘除_junit calculator

import static org.junit.Assert.*; import org.junit.Test; public class CalculatorTest { @Test public void testAdd() { final double INITIAL_VALUE = 25.5; Calculator calculator = new Calculator(INITIAL_VALUE); // Pre-condition: Calculator object exists assertEquals(INITIAL_VALUE, calculator.getAccumulator(), 0.0);// Pre-condition: Accumulator starts with known value final double CHANGE_IN_VALUE = -10.0; calculator.add(CHANGE_IN_VALUE); assertEquals(INITIAL_VALUE + CHANGE_IN_VALUE, calculator.getAccumulator(), 0.0); // Post-condition: result matches expectation with 0.0 variation (the "delta") System.err.println("testAdd:"+calculator); // using err stream to show output in "red" as a highlight that this is testing. } // end testAdd() @Test public void testDivideByZeroPositive() { final double INITIAL_VALUE = 123.4; Calculator calculator = new Calculator(INITIAL_VALUE); // Pre-condition: Accumulator starts with known value assertEquals(INITIAL_VALUE, calculator.getAccumulator(), 0.0); calculator.divide(0.0); assertEquals(Double.POSITIVE_INFINITY, calculator.getAccumulator(), 0.0); // Post-condition: Accumulator contains divide-by-zero result: Double.POSITIVE_INFINITY System.err.println("testDivideByZero:"+calculator); // using err stream to show output in "red" as a highlight that this is testing. } // end testDivideByZero() @Test public void testDivideByZeroNegative() { final double INITIAL_VALUE = -123.4; Calculator calculator = new Calculator(INITIAL_VALUE); // Pre-condition: Accumulator starts with known value assertEquals(INITIAL_VALUE, calculator.getAccumulator(), 0.0); calculator.divide(0.0); assertEquals(Double.NEGATIVE_INFINITY, calculator.getAccumulator(), 0.0); // Post-condition: Accumulator contains divide-by-zero result: Double.POSITIVE_INFINITY System.err.println("testDivideByZero:"+calculator); // using err stream to show output in "red" as a highlight that this is testing. } // end testDivideByZero() @Test public void testDivideBySelf() { final double INITIAL_VALUE = 25.5; Calculator calculator = new Calculator(INITIAL_VALUE); // Pre-condition: Accumulator starts with known value assertEquals(INITIAL_VALUE, calculator.getAccumulator(), 0.0); calculator.divide(INITIAL_VALUE); assertEquals(1.0, calculator.getAccumulator(), 0.0); // Post-condition: Accumulator contains 1.0 with 0.0 variation (0.0 is the "delta") System.err.println("testDivideBySelf:"+calculator); // using err stream to show output in "red" as a highlight that this is testing. } // end testDivideBySelf() @Test public void testMultiplyOverFlow() { Calculator calculator = new Calculator(Double.MAX_VALUE); // Pre-condition: Accumulator starts with maximum possible double value System.err.println("testMultiplyOverflow:INITIAL_VALUE:BEFORE:Double.MAX_VALUE:"+calculator); // using err stream to show output in "red" as a highlight that this is testing. calculator.multiply(Double.MAX_VALUE); assertEquals(Double.POSITIVE_INFINITY, calculator.getAccumulator(), 0.0); // Post-condition: Accumulator contains overflow result: Double.POSITIVE_INFINITY System.err.println("testMultiplyOverflow:AFTER:"+calculator); // using err stream to show output in "red" as a highlight that this is testing. } // end testMultiply() @Test public void testSqrtPositive() { final double INITIAL_VALUE = 25.0; // perfect square Calculator calculator = new Calculator(INITIAL_VALUE); // Pre-condition: Accumulator starts with known value calculator.sqrt(); assertEquals(5.0, calculator.getAccumulator(), 0.0); // Post-condition: Accumulator contains square root with 0.0 variation (0.0 is the "delta") System.err.println("testSqrtPositive:"+calculator); // using err stream to show output in "red" as a highlight that this is testing. } // end testSqrtPositive() @Test public void testSqrtNegative() { final double INITIAL_VALUE = -25.0; // not a square Calculator calculator = new Calculator(INITIAL_VALUE); // Pre-condition: Accumulator starts with known value that violates sqrt() rules. calculator.sqrt(); // would result in an "imaginary" number, also called a complex number, which cannot be handled by type "double" assertEquals(Double.NaN, calculator.getAccumulator(), 0.0); // Post-condition: Accumulator contains not-a-number constant Double.NaN System.err.println("testSqrtNegative:"+calculator); // using err stream to show output in "red" as a highlight that this is testing. } // end testSqrtNegative() } // end class CalculatorTest