FibonacciJavaStreamsTest.java

packagecom.thealgorithms.maths;

importjava.math.BigDecimal;
importjava.util.Optional;
importorg.junit.jupiter.api.Assertions;
importorg.junit.jupiter.api.Test;

/**
 * @author Albina Gimaletdinova on 25/07/2023
 */
publicclassFibonacciJavaStreamsTest {
privatestaticfinalStringEXCEPTION_MESSAGE = "Input index cannot be null or negative!";

@Test
publicvoidtestWithNegativeIndexShouldThrowException() {
Exceptionexception = Assertions.assertThrows(IllegalArgumentException.class, () -> FibonacciJavaStreams.calculate(newBigDecimal(-1)));
Assertions.assertEquals(EXCEPTION_MESSAGE, exception.getMessage());
 }

@Test
publicvoidtestCheckTheFirst4SequenceElements() {
checkElement(BigDecimal.ZERO, BigDecimal.ZERO);
checkElement(BigDecimal.ONE, BigDecimal.ONE);
checkElement(BigDecimal.TWO, BigDecimal.ONE);
checkElement(newBigDecimal(3), BigDecimal.TWO);
 }

@Test
publicvoidtestCheck10thSequenceElement() {
checkElement(BigDecimal.TEN, newBigDecimal(55));
 }

@Test
publicvoidtestCheck20thSequenceElement() {
checkElement(newBigDecimal(20), newBigDecimal(6765));
 }

@Test
publicvoidtestCheck30thSequenceElement() {
checkElement(newBigDecimal(30), newBigDecimal(832040));
 }

@Test
publicvoidtestCheck40thSequenceElement() {
checkElement(newBigDecimal(40), newBigDecimal(102334155));
 }

@Test
publicvoidtestCheck50thSequenceElement() {
checkElement(newBigDecimal(50), newBigDecimal(12586269025L));
 }

@Test
publicvoidtestCheck100thSequenceElement() {
checkElement(newBigDecimal(100), newBigDecimal("354224848179261915075"));
 }

@Test
publicvoidtestCheck200thSequenceElement() {
checkElement(newBigDecimal(200), newBigDecimal("280571172992510140037611932413038677189525"));
 }

privatestaticvoidcheckElement(BigDecimalindex, BigDecimalexpected) {
// when
Optional<BigDecimal> result = FibonacciJavaStreams.calculate(index);

// then
Assertions.assertTrue(result.isPresent());
Assertions.assertEquals(result.get(), expected);
 }
}