tests: improve for GeneratePermutations (TheAlgorithms#1263)

Author: kho-kho-kho

Backtracking/tests/GeneratePermutations.test.js

@@ -1,14 +1,33 @@
+import{factorial}from'../../Recursive/Factorial'
 import{permutations}from'../GeneratePermutations'
 
 describe('Permutations',()=>{
+it('Permutations of [a]',()=>{
+constperms=permutations(['a'])
+expect(perms).toHaveLength(factorial(1))
+expect(perms).toContainEqual(['a'])
+})
+
+it('Permutations of [true, false]',()=>{
+constperms=permutations([true,false])
+expect(perms).toHaveLength(factorial(2))
+expect(perms).toContainEqual([true,false])
+expect(perms).toContainEqual([false,true])
+})
+
 it('Permutations of [1, 2, 3]',()=>{
-expect(permutations([1,2,3])).toEqual([
-[1,2,3],
-[1,3,2],
-[2,1,3],
-[2,3,1],
-[3,1,2],
-[3,2,1]
-])
+constperms=permutations([1,2,3])
+expect(perms).toHaveLength(factorial(3))
+expect(perms).toContainEqual([1,2,3])
+expect(perms).toContainEqual([1,3,2])
+expect(perms).toContainEqual([2,1,3])
+expect(perms).toContainEqual([2,3,1])
+expect(perms).toContainEqual([3,1,2])
+expect(perms).toContainEqual([3,2,1])
+})
+
+it('Permutation counts across larger input arrays',()=>{
+expect(permutations([1,2,3,4,5,6,7,8])).toHaveLength(factorial(8))
+expect(permutations([1,2,3,4,5,6,7,8,9])).toHaveLength(factorial(9))
 })
 })