NumberOfDigitsTest.java

packagecom.thealgorithms.maths;

importstaticorg.junit.jupiter.api.Assertions.assertEquals;

importjava.util.function.IntFunction;
importjava.util.stream.Stream;
importorg.junit.jupiter.params.ParameterizedTest;
importorg.junit.jupiter.params.provider.Arguments;
importorg.junit.jupiter.params.provider.MethodSource;

publicclassNumberOfDigitsTest {

@ParameterizedTest
@MethodSource("testCases")
voidtestNumberOfDigits(finalintexpected, finalintnumber, finalIntFunction<Integer> methodUnderTest) {
assertEquals(expected, methodUnderTest.apply(number));
assertEquals(expected, methodUnderTest.apply(-number));
 }

privatestaticStream<Arguments> testCases() {
finalInteger[][] inputs = newInteger[][] {
 {3, 100},
 {1, 0},
 {2, 12},
 {3, 123},
 {4, 1234},
 {5, 12345},
 {6, 123456},
 {7, 1234567},
 {8, 12345678},
 {9, 123456789},
 {9, 987654321},
 };

finalIntFunction<Integer>[] methods = newIntFunction[] {NumberOfDigits::numberOfDigits, NumberOfDigits::numberOfDigitsFast, NumberOfDigits::numberOfDigitsFaster, NumberOfDigits::numberOfDigitsRecursion};

returnStream.of(inputs).flatMap(input -> Stream.of(methods).map(method -> Arguments.of(input[0], input[1], method)));
 }
}