test: DeterminantOfMatrix (#5376)

Author: alxkm

src/main/java/com/thealgorithms/maths/DeterminantOfMatrix.java

@@ -1,7 +1,5 @@
 package com.thealgorithms.maths;
 
-import java.util.Scanner;
-
 /*
  * @author Ojasva Jain
  * Determinant of a Matrix Wikipedia link: https://en.wikipedia.org/wiki/Determinant
@@ -10,8 +8,13 @@ public final class DeterminantOfMatrix {
     private DeterminantOfMatrix() {
     }
 
-    // Determinant calculator
-    //@return determinant of the input matrix
+    /**
+     * Calculates the determinant of a given matrix.
+     *
+     * @param a the input matrix
+     * @param n the size of the matrix
+     * @return the determinant of the matrix
+     */
     static int determinant(int[][] a, int n) {
         int det = 0;
         int sign = 1;
@@ -41,21 +44,4 @@ static int determinant(int[][] a, int n) {
         }
         return det;
     }
-
-    // Driver Method
-    public static void main(String[] args) {
-        Scanner in = new Scanner(System.in);
-        // Input Matrix
-        System.out.println("Enter matrix size (Square matrix only)");
-        int n = in.nextInt();
-        System.out.println("Enter matrix");
-        int[][] a = new int[n][n];
-        for (int i = 0; i < n; i++) {
-            for (int j = 0; j < n; j++) {
-                a[i][j] = in.nextInt();
-            }
-        }
-        System.out.println(determinant(a, n));
-        in.close();
-    }
 }

src/test/java/com/thealgorithms/maths/DeterminantOfMatrixTest.java

@@ -0,0 +1,50 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class DeterminantOfMatrixTest {
+
+    @Test
+    public void testDeterminant2x2Matrix() {
+        int[][] matrix = {{1, 2}, {3, 4}};
+        int expected = -2;
+        assertEquals(expected, DeterminantOfMatrix.determinant(matrix, 2));
+    }
+
+    @Test
+    public void testDeterminant3x3Matrix() {
+        int[][] matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
+        int expected = 0;
+        assertEquals(expected, DeterminantOfMatrix.determinant(matrix, 3));
+    }
+
+    @Test
+    public void testDeterminant3x3MatrixNonZero() {
+        int[][] matrix = {{1, 2, 3}, {0, 1, 4}, {5, 6, 0}};
+        int expected = 1;
+        assertEquals(expected, DeterminantOfMatrix.determinant(matrix, 3));
+    }
+
+    @Test
+    public void testDeterminant1x1Matrix() {
+        int[][] matrix = {{7}};
+        int expected = 7;
+        assertEquals(expected, DeterminantOfMatrix.determinant(matrix, 1));
+    }
+
+    @Test
+    public void testDeterminant4x4Matrix() {
+        int[][] matrix = {{1, 0, 0, 1}, {0, 1, 0, 0}, {0, 0, 1, 0}, {1, 0, 0, 1}};
+        int expected = 0;
+        assertEquals(expected, DeterminantOfMatrix.determinant(matrix, 4));
+    }
+
+    @Test
+    public void testDeterminant4x4MatrixZero() {
+        int[][] matrix = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}};
+        int expected = 0;
+        assertEquals(expected, DeterminantOfMatrix.determinant(matrix, 4));
+    }
+}