Completed todo test

Author: Maryanne-K

Sprint-2/implement/tally.test.js

@@ -19,19 +19,43 @@ const tally = require("./tally.js");
 // Given a function called tally
 // When passed an array of items
 // Then it should return an object containing the count for each unique item
-test.todo("tally returns correct counts for unique items in an array");
+test("tally returns correct counts for unique items in an array", () => {
+  const input = ["a", "b", "c"];
+  const result = tally(input);
 
+  expect(result).toEqual({
+    a: 1,
+    b: 1,
+    c: 1,
+  });
+});
 // Given an empty array
 // When passed to tally
 // Then it should return an empty object
-test.todo("tally on an empty array returns an empty object");
+test("tally on an empty array returns an empty object", () => {
+  const result = tally([]);
 
+  expect(result).toEqual({});
+});
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
-test.todo("tally returns correct counts for duplicate items in an array");
+test("tally returns correct counts for duplicate items in an array", () => {
+  const input = ["a", "a", "b", "c"];
+  const result = tally(input);
+
+  expect(result).toEqual({
+    a: 2,
+    b: 1,
+    c: 1
+  });
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
-test.todo("tally with invalid input throws an error");
+test("tally with invalid input throws an error", () => {
+  expect(() => tally("invalid input")).toThrow();
+  expect(() => tally(123)).toThrow();
+  expect(() => tally(null)).toThrow();
+});