Added tests for contains function

Author: Eugenie-A

Sprint-2/implement/contains.test.js

@@ -16,20 +16,40 @@ as the object doesn't contains a key of 'c'
 // Given a contains function
 // When passed an object and a property name
 // Then it should return true if the object contains the property, false otherwise
+test("returns true when the property exists in the object", () => {
+  expect(contains({ a: 1, b: 2 }, "a")).toBe(true);
+  expect(contains({ a: 1, b: 2 }, "b")).toBe(true);
+});
 
 // Given an empty object
 // When passed to contains
 // Then it should return false
-test.todo("contains on empty object returns false");
+test("contains on empty object returns false", () => {
+  expect(contains({}, "a")).toBe(false);
+  expect(contains({}, "toString")).toBe(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+test("returns true for existing property name", () => {
+  expect(contains({ name: "Alex" }, "name")).toBe(true);
+  expect(contains({ id: 42 }, "id")).toBe(true);
+});
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("returns false for non-existent property name", () => {
+  expect(contains({ name: "Alex", age: 42 }, "email")).toBe(false);
+  expect(contains({ age: 54 }, "name")).toBe(false);
+});
 
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("handles invalid parameters like an array", () => {
+  expect(contains([], "length")).toBe(false);
+  expect(contains(123, "length")).toBe(false);
+  expect(contains("string", "length")).toBe(false);
+});