Added test case to sudoku

Author: captiosus1

src/test/java/com/thealgorithms/others/SudokuTest.java

@@ -0,0 +1,76 @@
+package com.thealgorithms.others;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import org.junit.jupiter.api.Test;
+
+public class SudokuTest {
+
+    @Test
+    public void testSolvableSudoku() {
+        int[][] board = new int[][]{
+                {3, 0, 6, 5, 0, 8, 4, 0, 0},
+                {5, 2, 0, 0, 0, 0, 0, 0, 0},
+                {0, 8, 7, 0, 0, 0, 0, 3, 1},
+                {0, 0, 3, 0, 1, 0, 0, 8, 0},
+                {9, 0, 0, 8, 6, 3, 0, 0, 5},
+                {0, 5, 0, 0, 9, 0, 6, 0, 0},
+                {1, 3, 0, 0, 0, 0, 2, 5, 0},
+                {0, 0, 0, 0, 0, 0, 0, 7, 4},
+                {0, 0, 5, 2, 0, 6, 3, 0, 0}
+        };
+
+        assertTrue(Sudoku.solveSudoku(board, board.length), "The puzzle should be solvable.");
+    }
+
+    @Test
+    public void testUnsolvableSudoku() {
+        int[][] board = new int[][]{
+                {3, 0, 6, 5, 0, 8, 4, 0, 0},
+                {5, 2, 1, 0, 0, 0, 0, 0, 0},
+                {9, 8, 7, 0, 0, 0, 0, 3, 1},
+                {0, 0, 3, 0, 1, 0, 0, 8, 0},
+                {9, 0, 0, 8, 6, 3, 0, 0, 5},
+                {0, 5, 0, 0, 9, 0, 6, 0, 0},
+                {1, 3, 0, 0, 0, 0, 2, 5, 0},
+                {0, 0, 0, 0, 0, 0, 0, 7, 4},
+                {0, 0, 5, 2, 0, 6, 3, 1, 0}
+        };
+
+        assertFalse(Sudoku.solveSudoku(board, board.length), "The puzzle should be unsolvable.");
+    }
+
+    @Test
+    public void testEmptySudoku() {
+        int[][] board = new int[][]{
+                {0, 0, 0, 0, 0, 0, 0, 0, 0},
+                {0, 0, 0, 0, 0, 0, 0, 0, 0},
+                {0, 0, 0, 0, 0, 0, 0, 0, 0},
+                {0, 0, 0, 0, 0, 0, 0, 0, 0},
+                {0, 0, 0, 0, 0, 0, 0, 0, 0},
+                {0, 0, 0, 0, 0, 0, 0, 0, 0},
+                {0, 0, 0, 0, 0, 0, 0, 0, 0},
+                {0, 0, 0, 0, 0, 0, 0, 0, 0},
+                {0, 0, 0, 0, 0, 0, 0, 0, 0}
+        };
+
+        assertTrue(Sudoku.solveSudoku(board, board.length), "An empty puzzle should be solvable.");
+    }
+
+    @Test
+    public void testAlreadySolvedSudoku() {
+        int[][] board = new int[][]{
+                {5, 3, 4, 6, 7, 8, 9, 1, 2},
+                {6, 7, 2, 1, 9, 5, 3, 4, 8},
+                {1, 9, 8, 3, 4, 2, 5, 6, 7},
+                {8, 5, 9, 7, 6, 1, 4, 2, 3},
+                {4, 2, 6, 8, 5, 3, 7, 9, 1},
+                {7, 1, 3, 9, 2, 4, 8, 5, 6},
+                {9, 6, 1, 5, 3, 7, 2, 8, 4},
+                {2, 8, 7, 4, 1, 9, 6, 3, 5},
+                {3, 4, 5, 2, 8, 6, 1, 7, 9}
+        };
+
+        assertTrue(Sudoku.solveSudoku(board, board.length), "An already solved puzzle should return true.");
+    }
+}