StringBasicsTest.java

package part01;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assumptions.assumeTrue;

import org.junit.jupiter.api.Test;

public class StringBasicsTest {

    // The object we are testing
    private StringBasics solution = new StringBasics();

    @Test
    void truncateShortensTheGivenStringToTheMaximumLength() {
        assertEquals("He", solution.truncate("Hello", 2),
                "Text should be truncated to 2 characters");

        assertEquals("Hello", solution.truncate("Hello", 5),
                "Text is not truncated when length is equal to the text length");

        assertEquals("Hello", solution.truncate("Hello", 10),
                "Text is not truncated when length is greater than the text length");
    }

    @Test
    void parseYesOrNoReturnsTheCorrectBooelanValues() {
        // Test that the method returns true for all variations of "yes"
        assertTrue(solution.parseYesOrNo("yes"), "yes in lower case");
        assertTrue(solution.parseYesOrNo("YES"), "yes in upper case");
        assertTrue(solution.parseYesOrNo("Yes"), "yes with first letter in upper case");

        // Test that the method returns false for all variations of "no"
        assertFalse(solution.parseYesOrNo("no"), "no in lower case");
        assertFalse(solution.parseYesOrNo("NO"), "no in upper case");
        assertFalse(solution.parseYesOrNo("No"), "no with first letter in upper case");
    }

    @Test
    void fizzBuzzReturnsTheCorrectWordsForEachNumber() {
        // Test that the method returns Fizz for all numbers divisible by 3
        assertEqualsIgnoreCase("Fizz", solution.getFizzBuzz(3));
        assertEqualsIgnoreCase("Fizz", solution.getFizzBuzz(6));
        assertEqualsIgnoreCase("Fizz", solution.getFizzBuzz(9));
        assertEqualsIgnoreCase("Fizz", solution.getFizzBuzz(12));

        // Test that the method returns Buzz for all numbers divisible by 5
        assertEqualsIgnoreCase("Buzz", solution.getFizzBuzz(5));
        assertEqualsIgnoreCase("Buzz", solution.getFizzBuzz(10));

        // Test that the method returns FizzBuzz for all numbers divisible by 3 and 5
        assertEqualsIgnoreCase("FizzBuzz", solution.getFizzBuzz(15));

        // Test that the method returns the number as a string for all other numbers
        assertEqualsIgnoreCase("1", solution.getFizzBuzz(1));
        assertEqualsIgnoreCase("2", solution.getFizzBuzz(2));
        assertEqualsIgnoreCase("4", solution.getFizzBuzz(4));
        assertEqualsIgnoreCase("7", solution.getFizzBuzz(7));
        assertEqualsIgnoreCase("8", solution.getFizzBuzz(8));
        assertEqualsIgnoreCase("11", solution.getFizzBuzz(11));
        assertEqualsIgnoreCase("13", solution.getFizzBuzz(13));
        assertEqualsIgnoreCase("14", solution.getFizzBuzz(14));

        // Finally, test that the method can handle large numbers
        assertEqualsIgnoreCase("FizzBuzz", solution.getFizzBuzz(1_500_000_000));
    }

    /**
     * This method is a helper method to compare two strings ignoring case.
     */
    private void assertEqualsIgnoreCase(String expected, String actual) {
        assertNotNull(expected, "Expected " + expected + " but was null");

        assertEquals(expected.toLowerCase(), actual.toLowerCase());
    }

    @Test
    void centerReturnsTheTextCenteredInTheGivenWidth() {
        // Hello with equal spaces on both sides:
        assertEquals("  Hello  ", solution.center("Hello", 9));

        // Java with equal spaces on both sides:
        assertEquals("        Java        ", solution.center("Java", 20));

        // A string that is longer than the given width should not be modified:
        assertEquals("Long string", solution.center("Long string", 5));

        // When odd number of spaces, the extra space can be added on either side
        String centered = solution.center("Java", 9);

        assertEquals(9, centered.length(),
                "The length of the centered string '%s' should be 9, but was %d"
                        .formatted(centered, centered.length()));
        assertTrue(centered.contains("  Java  "), "There should be at least two spaces around the text");
    }

    /**
     * The centerMultiLine method is not required, and it's only tested if you
     * choose to implement it. The `assumeTrue` method skips the test if the
     * method returns null.
     */
    @Test
    void centerMultiLineReturnsTheTextCenteredInTheGivenWidth() {

        // https://junit.org/junit5/docs/5.0.0/api/org/junit/jupiter/api/Assumptions.html
        assumeTrue(solution.centerMultiLine("Hello", 5) != null,
                "This test is skipped if the centerMultiLine method returns null.");

        // A single line text should be centered as usual
        assertEquals("  Windows 95  ", solution.centerMultiLine("Windows 95", 14));

        // A multi-line text should be centered line by line
        assertEquals("  Java  \n   21   ", solution.centerMultiLine("Java\n21", 8));

        // Some lines may be longer than the given width
        assertEquals("  Hello!  \nTerve maailma!", solution.centerMultiLine("Hello!\nTerve maailma!", 10));
    }
}