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Diane Duanadamd1985
Diane Duan
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adamd1985
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BAEL-640: Guide to Mathematical Operations with Guava (eugenp#1390)
* Guava IntMath tests * Guava DoubleMath test * break down testDoubleMath()
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‎guava/src/test/java/org/baeldung/guava/GuavaMathTest.java‎

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package org.baeldung.guava;
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import com.google.common.math.DoubleMath;
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import com.google.common.math.IntMath;
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import org.junit.Rule;
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import org.junit.Test;
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import org.junit.rules.ExpectedException;
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import java.math.BigInteger;
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import java.math.RoundingMode;
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import static org.hamcrest.core.IsEqual.equalTo;
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import static org.junit.Assert.assertFalse;
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import static org.junit.Assert.assertThat;
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import static org.junit.Assert.assertTrue;
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public class GuavaMathTest {
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@Test
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public void testIntMathAdd() {
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try {
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IntMath.checkedAdd(Integer.MAX_VALUE, 1);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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}
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try {
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IntMath.checkedAdd(Integer.MIN_VALUE, -1);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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}
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int result1 = IntMath.checkedAdd(2, 1);
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assertThat(result1, equalTo(3));
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int result2 = IntMath.saturatedAdd(Integer.MAX_VALUE, 100);
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assertThat(result2, equalTo(Integer.MAX_VALUE));
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int result3 = IntMath.saturatedAdd(Integer.MIN_VALUE, -100);
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assertThat(result3, equalTo(Integer.MIN_VALUE));
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}
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@Test
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public void testIntMathSubtract() {
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try {
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IntMath.checkedSubtract(Integer.MIN_VALUE, 1);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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}
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try {
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IntMath.checkedSubtract(Integer.MAX_VALUE, -1);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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};
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int result1 = IntMath.checkedSubtract(200, 100);
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assertThat(result1, equalTo(100));
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int result2 = IntMath.saturatedSubtract(Integer.MIN_VALUE, 1);
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assertThat(result2, equalTo(Integer.MIN_VALUE));
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int result3 = IntMath.saturatedSubtract(Integer.MAX_VALUE, -1);
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assertThat(result3, equalTo(Integer.MAX_VALUE));
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}
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@Test
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public void testIntMathMultiply() {
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try {
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IntMath.checkedMultiply(Integer.MAX_VALUE, 2);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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}
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try {
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IntMath.checkedMultiply(Integer.MIN_VALUE, 2);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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}
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int result1 = IntMath.checkedMultiply(21, 3);
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assertThat(result1, equalTo(63));
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int result2 = IntMath.saturatedMultiply(Integer.MAX_VALUE, 2);
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assertThat(result2, equalTo(Integer.MAX_VALUE));
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int result3 = IntMath.saturatedMultiply(Integer.MIN_VALUE, 2);
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assertThat(result3, equalTo(Integer.MIN_VALUE));
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}
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@Test
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public void testIntMathPow() {
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try {
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IntMath.checkedPow(Integer.MAX_VALUE, 2);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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}
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try {
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IntMath.checkedPow(Integer.MIN_VALUE, 3);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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}
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int result1 = IntMath.saturatedPow(3, 3);
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assertThat(result1, equalTo(27));
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int result2 = IntMath.saturatedPow(Integer.MAX_VALUE, 2);
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assertThat(result2, equalTo(Integer.MAX_VALUE));
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int result3 = IntMath.saturatedPow(Integer.MIN_VALUE, 3);
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assertThat(result3, equalTo(Integer.MIN_VALUE));
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}
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@Test
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public void testIntMathRound() {
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int result1 = IntMath.divide(3, 2, RoundingMode.DOWN);
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assertThat(result1, equalTo(1));
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int result2 = IntMath.divide(3, 2, RoundingMode.UP);
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assertThat(result2, equalTo(2));
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int result3 = IntMath.log2(5, RoundingMode.FLOOR);
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assertThat(result3, equalTo(2));
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int result4 = IntMath.log2(5, RoundingMode.CEILING);
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assertThat(result4, equalTo(3));
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int result5 = IntMath.log10(11, RoundingMode.HALF_UP);
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assertThat(result5, equalTo(1));
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int result6 = IntMath.sqrt(4, RoundingMode.UNNECESSARY);
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assertThat(result6, equalTo(2));
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try {
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IntMath.sqrt(5, RoundingMode.UNNECESSARY);
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assertTrue(false);
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} catch (ArithmeticException e) {
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assertTrue(true);
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}
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}
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@Test
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public void testIntMathAdditionalFunctions() {
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int result1 = IntMath.gcd(15, 20);
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assertThat(result1, equalTo(5));
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int result2 = IntMath.mod(8, 3);
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assertThat(result2, equalTo(2));
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boolean result3 = IntMath.isPowerOfTwo(8);
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assertTrue(result3);
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boolean result4 = IntMath.isPowerOfTwo(9);
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assertFalse(result4);
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int result5 = IntMath.factorial(4);
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assertThat(result5, equalTo(24));
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int result6 = IntMath.binomial(7, 3);
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assertThat(result6, equalTo(35));
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}
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@Test
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public void should_detect_integer() {
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boolean result1 = DoubleMath.isMathematicalInteger(2.0);
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assertThat(result1, equalTo(true));
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boolean result2 = DoubleMath.isMathematicalInteger(2.1);
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assertThat(result2, equalTo(false));
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}
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@Test
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public void should_round_to_integer_types() {
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int result3 = DoubleMath.roundToInt(2.5, RoundingMode.DOWN);
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assertThat(result3, equalTo(2));
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long result4 = DoubleMath.roundToLong(2.5, RoundingMode.HALF_UP);
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assertThat(result4, equalTo(3L));
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BigInteger result5 = DoubleMath.roundToBigInteger(2.5, RoundingMode.UP);
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assertThat(result5, equalTo(new BigInteger("3")));
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}
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@Test
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public void should_calculate_log_2() {
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int result6 = DoubleMath.log2(10, RoundingMode.UP);
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assertThat(result6, equalTo(4));
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}
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}

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