reimplement contains and add test case for array inputs

Author: RaihanSharif

Sprint-2/implement/contains.js

@@ -4,7 +4,7 @@ function isObject(item) {
 
 function contains(object, key) {
   if (isObject(object)) {
-    return Object.keys(object).includes(key);
+    return key in object;
   }
   throw new TypeError("Item is not plain object, Date, or Map");
 }

Sprint-2/implement/contains.test.js

@@ -43,4 +43,5 @@ test("given an object, and property that does not exist in object, should return
 // Then it should return false or throw an error
 test("given invalid parameter, like an array, should return false or throw error", () => {
   expect(() => contains(22, "a")).toThrow(TypeError);
+  expect(() => contains([], "a")).toThrow(TypeError);
 });