import static org.assertj.core.api.Assertions.assertThat; import static org.assertj.core.api.Assertions.assertThatExceptionOfType; import org.junit.jupiter.api.Disabled; import org.junit.jupiter.api.DisplayName; import org.junit.jupiter.api.Test; import java.util.Arrays; import java.util.Collections; import java.util.List; import java.util.SortedMap; import java.util.stream.Collectors; public class PalindromeCalculatorTest { private PalindromeCalculator palindromeCalculator = new PalindromeCalculator(); @Test @DisplayName("find the smallest palindrome from single digit factors") public void smallestPalindromeFromSingleDigitFactors() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(1, 1) ) ); long expectedValue = 1L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(1, 9); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.firstKey()); } @Disabled("Remove to run test") @Test @DisplayName("find the largest palindrome from single digit factors") public void largestPalindromeFromSingleDigitFactors() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(1, 9), Arrays.asList(3, 3) ) ); long expectedValue = 9L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(1, 9); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.lastKey()); } @Disabled("Remove to run test") @Test @DisplayName("find the smallest palindrome from double digit factors") public void largestPalindromeFromDoubleDigitFactors() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(91, 99) ) ); long expectedValue = 9009L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(10, 99); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.lastKey()); } @Disabled("Remove to run test") @Test @DisplayName("find the largest palindrome from double digit factors") public void smallestPalindromeFromDoubleDigitFactors() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(11, 11) ) ); long expectedValue = 121L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(10, 99); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.firstKey()); } @Disabled("Remove to run test") @Test @DisplayName("find the largest palindrome from triple digit factors") public void largestPalindromeFromTripleDigitFactors() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(913, 993) ) ); long expectedValue = 906609L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(100, 999); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.lastKey()); } @Disabled("Remove to run test") @Test @DisplayName("find the smallest palindrome from triple digit factors") public void smallestPalindromeFromTripleDigitFactors() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(101, 101) ) ); long expectedValue = 10201L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(100, 999); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.firstKey()); } @Disabled("Remove to run test") @Test @DisplayName("find the smallest palindrome from four digit factors") public void smallestPalindromeFromQuadDigitFactors() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(1001, 1001) ) ); long expectedValue = 1002001L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(1000, 9999); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.firstKey()); } @Disabled("Remove to run test") @Test @DisplayName("find the largest palindrome from four digit factors") public void largestPalindromeFromQuadDigitFactors() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(9901, 9999) ) ); long expectedValue = 99000099L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(1000, 9999); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.lastKey()); } @Disabled("Remove to run test") @Test @DisplayName("empty result for smallest if no palindrome in the range") public void emtpyResultSmallestNoPalindromeInRange() { SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(1002, 1003); assertThat(palindromes).isEmpty(); } @Disabled("Remove to run test") @Test @DisplayName("empty result for largest if no palindrome in the range") public void emptyResultLargestNoPalindromeInRange() { SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(15, 15); assertThat(palindromes).isEmpty(); } @Disabled("Remove to run test") @Test @DisplayName("error result for smallest if min is more than max") public void errorSmallestMinIsMoreThanMax() { assertThatExceptionOfType(IllegalArgumentException.class) .isThrownBy(() -> palindromeCalculator.getPalindromeProductsWithFactors(10000, 1)) .withMessage("invalid input: min must be <= max"); } @Disabled("Remove to run test") @Test @DisplayName("error result for largest if min is more than max") public void errorLargestMinIsMoreThanMax() { assertThatExceptionOfType(IllegalArgumentException.class) .isThrownBy(() -> palindromeCalculator.getPalindromeProductsWithFactors(2, 1)) .withMessage("invalid input: min must be <= max"); } @Disabled("Remove to run test") @Test @DisplayName("smallest product does not use the smallest factor") public void smallestProductDoesNotUseTheSmallestFactor() { List> expected = Collections.unmodifiableList( Arrays.asList( Arrays.asList(3297, 3333) ) ); long expectedValue = 10988901L; SortedMap>> palindromes = palindromeCalculator.getPalindromeProductsWithFactors(3215, 4000); checkPalindromeWithFactorsMatchesExpected(expected, expectedValue, palindromes, palindromes.firstKey()); } private void checkPalindromeWithFactorsMatchesExpected(List> expectedPalindromeFactors, long expectedValueOfPalindrome, SortedMap>> actualPalindromes, long actualValueOfPalindrome) { assertThat(actualPalindromes) .isNotNull() .isNotEmpty(); assertThat(actualValueOfPalindrome).isEqualTo(expectedValueOfPalindrome); List> actualPalindromeFactors = actualPalindromes .get(actualValueOfPalindrome) .stream() .sorted((a, b) -> Integer.compare(a.get(0), b.get(0))) .collect(Collectors.toList()); assertThat(actualPalindromeFactors).containsExactlyElementsOf(expectedPalindromeFactors); } }