KATA TIME™ - Sorting the Triangle!

Session 2 - "These triangles ain't gonna sort themselves!" - Hannah Montana

Today's Kata

Triangle Sorter

"A triangle is a polygon with three edges and three vertices."

- Wikipedia

"If triangles invented a god, they would make him three-sided."

- Baron de Montesquieu

The goal of this kata is to take 3 integer values that represent the lengths of three sides of a triangle and return a String representation of the triangle's classification. The 5 classifications we are looking for will be 'equilateral', 'isosceles', 'right', 'other', and 'not a triangle'.

Today's Goals

Doing the simplest thing to make a test pass.
Discuss ordering of test cases.
Making sure edge cases are tested.
Playing with lists.
Advanced refactoring of test classes.

Code Along Repo Link

Github Classroom - Triangle Sorter

Session Video

KATA TIME™ - 2/5/2021 - Triangle Sorter

Session Code

	package triangle_sorter;

	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collections;

	public class TriangleSorter {
	public String analyze(Integer... sides) {
	ArrayList<Integer> sortedSides = new ArrayList<>(Arrays.asList(sides));
	Collections.sort(sortedSides);
	int sideA = sortedSides.get(0);
	int sideB = sortedSides.get(1);
	int sideC = sortedSides.get(2);

	if(isAnEquilateralTriangle(sideA, sideB, sideC)){
	return "Equilateral";
	}

	if(isARightTriangle(sideA, sideB, sideC)){
	return "Right";
	}
	if(isNotATriangle(sideA, sideB, sideC)){
	return "Not a triangle";
	}
	if (isAnIsoscelesTriangle(sideA, sideB , sideC)) {
	return "Isosceles";
	}

	return "Other";
	}

	private boolean isNotATriangle(int sideA, int sideB, int sideC) {
	return sideA + sideB <= sideC;
	}

	private boolean isARightTriangle(int sideA, int sideB, int sideC) {
	return Math.pow(sideA, 2) + Math.pow(sideB, 2) == Math.pow(sideC, 2);
	}

	private boolean isAnEquilateralTriangle(int sideA, int sideB, int sideC) {
	return sideA == sideB && sideB == sideC;
	}

	private boolean isAnIsoscelesTriangle(int sideA, int sideB, int sideC) {
	return sideA == sideB \|\| sideB == sideC;
	}
	}

view raw TriangleSorter.java hosted with ❤ by GitHub

	package triangle_sorter;

	import org.junit.jupiter.api.BeforeEach;
	import org.junit.jupiter.api.Test;

	import static org.hamcrest.MatcherAssert.assertThat;
	import static org.hamcrest.core.Is.is;

	public class TriangleSorterTest {

	private static final String EQUILATERAL = "Equilateral";
	public static final String ISOSCELES = "Isosceles";
	private TriangleSorter underTest;

	@BeforeEach
	void setUp() {
	underTest = new TriangleSorter();
	}

	@Test
	public void analyzeReturnsEquilateralTriangleWhenGivenAnEquilateralTriangle() {
	assertTriangleType(EQUILATERAL, 3, 3, 3);
	assertTriangleType(EQUILATERAL, 4, 4, 4);
	assertTriangleType(EQUILATERAL, 5, 5, 5);
	}


	@Test
	public void analyzeReturnsIsoscelesTriangleWhenGivenAnIsoscelesTriangle() {
	assertTriangleType(ISOSCELES, 3, 3, 2);
	assertTriangleType(ISOSCELES, 3, 3, 4);
	assertTriangleType(ISOSCELES, 3, 4, 3);
	}

	@Test
	public void analyzeReturnsRightTriangleWhenGivenARightTriangle() {
	assertTriangleType("Right", 3, 4, 5);
	assertTriangleType("Right", 5, 12, 13);
	assertTriangleType("Right", 5, 4, 3);
	}

	@Test
	public void analyzeReturnsOtherWhenGivenAnOtherTriangle() {
	assertTriangleType("Other", 100, 300, 313);
	}

	@Test
	public void analyzeReturnsNotATriangleWhenGivenThreeValuesTHatDoNotFormATriangle() {
	assertTriangleType("Not a triangle", 1, 1, 100);
	}


	private void assertTriangleType(String expectedType, int sideA, int sideB, int sideC) {
	String triangleType = underTest.analyze(sideA, sideB, sideC);
	assertThat(triangleType, is(expectedType));
	}
	}

view raw TriangleSorterTest.java hosted with ❤ by GitHub

	package triangle_sorter;

	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.List;

	public class TriangleSorter {
	public String analyze(int sideA, int sideB, int sideC) {
	ArrayList<Integer> sortedSides = new ArrayList<>(List.of(sideA, sideB, sideC));
	Collections.sort(sortedSides);
	int sortedSideA = sortedSides.get(0);
	int sortedSideB = sortedSides.get(1);
	int sortedSideC = sortedSides.get(2);

	if (isAnEquilateralTriangle(sortedSideA, sortedSideB, sortedSideC)) {
	return "Equilateral";
	}

	if (isARightTriangle(sortedSideA, sortedSideB, sortedSideC)) {
	return "Right";
	}
	if (isNotATriangle(sortedSideA, sortedSideB, sortedSideC)) {
	return "Not a triangle";
	}
	if (isAnIsoscelesTriangle(sortedSideA, sortedSideB, sortedSideC)) {
	return "Isosceles";
	}

	return "Other";
	}

	private boolean isNotATriangle(int sideA, int sideB, int sideC) {
	return sideA + sideB <= sideC;
	}

	private boolean isARightTriangle(int sideA, int sideB, int sideC) {
	return Math.pow(sideA, 2) + Math.pow(sideB, 2) == Math.pow(sideC, 2);
	}

	private boolean isAnEquilateralTriangle(int sideA, int sideB, int sideC) {
	return sideA == sideB && sideB == sideC;
	}

	private boolean isAnIsoscelesTriangle(int sideA, int sideB, int sideC) {
	return sideA == sideB \|\| sideB == sideC;
	}
	}

view raw TriangleSorterWithoutVarargs.java hosted with ❤ by GitHub