Renamed NQueen file, variables to NQueens, raised RangeError exception (TheAlgorithms#1162)

Author: SudhanshuSuman

Backtracking/NQueen.js renamed to Backtracking/NQueens.js

@@ -1,5 +1,8 @@
-class NQueen {
+class NQueens {
   constructor (size) {
+    if (size < 0) {
+      throw RangeError('Invalid board size')
+    }
     this.board = new Array(size).fill('.').map(() => new Array(size).fill('.'))
     this.size = size
     this.solutionCount = 0
@@ -61,4 +64,4 @@ class NQueen {
   }
 }
 
-export { NQueen }
+export { NQueens }

Backtracking/tests/NQueen.test.js

@@ -0,0 +1,19 @@
+import { NQueens } from '../NQueens'
+
+describe('NQueens', () => {
+  it('should return 2 solutions for 4x4 size board', () => {
+    const _4Queens = new NQueens(4)
+    _4Queens.solve()
+    expect(_4Queens.solutionCount).toEqual(2)
+  })
+
+  it('should return 92 solutions for 8x8 size board', () => {
+    const _8Queens = new NQueens(8)
+    _8Queens.solve()
+    expect(_8Queens.solutionCount).toEqual(92)
+  })
+
+  it('should throw RangeError for negative size board', () => {
+    expect(() => { return new NQueens(-1) }).toThrow(RangeError)
+  })
+})