completed till tests and function

Author: TzeMingHo

Sprint-2/stretch/till.js

@@ -5,13 +5,24 @@
 // Then it should return the total amount in pounds
 
 function totalTill(till) {
+  if (typeof till !== "object" || Array.isArray(till) || till === null) {
+    throw new Error("Input should be an object");
+  }
+
+  const validPence = ["1p", "5p", "20p", "50p"];
+
   let total = 0;
 
+  console.log(Object.entries(till));
+
   for (const [coin, quantity] of Object.entries(till)) {
-    total += coin * quantity;
+    if (validPence.indexOf(coin) === -1) {
+      continue;
+    }
+    total += Number(coin.slice(0, coin.length - 1)) * quantity;
   }
 
-  return `£${total / 100}`;
+  return `£${Math.floor(total / 100)}.${String(total % 100).padEnd(2, 0)}`;
 }
 
 const till = {
@@ -22,10 +33,18 @@ const till = {
 };
 const totalAmount = totalTill(till);
 
+module.exports = totalTill;
+
 // a) What is the target output when totalTill is called with the till object
+// The target output is a string that state the total value of pound after converted from pence
+// For example: '£4.40'
 
 // b) Why do we need to use Object.entries inside the for...of loop in this function?
+// We need to convert the object till into an array of arrays [ [ '1p', 10 ], [ '5p', 6 ], [ '50p', 4 ], [ '20p', 10 ] ]
+// That will enable the loop process in the for loop.
 
 // c) What does coin * quantity evaluate to inside the for...of loop?
+// coin * quantity was trying to get the value of each group of pence and add to the total
+// However, coin is referencing to first element of each sub array, which is a string that can't do math operation
 
 // d) Write a test for this function to check it works and then fix the implementation of totalTill

Sprint-2/stretch/till.test.js

@@ -0,0 +1,48 @@
+const totalTill = require("./till");
+
+test("Given a non object, it should throw error message", () => {
+  const errorMessage = "Input should be an object";
+  expect(() => totalTill([])).toThrow(errorMessage);
+  expect(() => totalTill(123)).toThrow(errorMessage);
+  expect(() => totalTill("123")).toThrow(errorMessage);
+  expect(() => totalTill(null)).toThrow(errorMessage);
+  expect(() => totalTill(undefined)).toThrow(errorMessage);
+  expect(() => totalTill(true)).toThrow(errorMessage);
+});
+
+test("Given an empty object, it should return £0.00", () => {
+  expect(totalTill({})).toBe("£0.00");
+});
+
+test("Given a pence object, it should return value of pound", () => {
+  const till = {
+    "1p": 10,
+    "5p": 6,
+    "50p": 4,
+    "20p": 10,
+  };
+  expect(totalTill(till)).toBe("£4.40");
+});
+
+test("Given a large amount of pence object, it should return proper value of pound", () => {
+  const till = {
+    "1p": 1234,
+    "5p": 567,
+    "50p": 890,
+    "20p": 1011,
+  };
+  expect(totalTill(till)).toBe("£687.89");
+});
+
+test("Given a pence object mixed with something else, it should ignore invalid input and return the value of pound", () => {
+  const till = {
+    "1p": 10,
+    "5p": 6,
+    fakeCoin: 10,
+    undefined: 1,
+    null: 2,
+    "50p": 4,
+    "20p": 10,
+  };
+  expect(totalTill(till)).toBe("£4.40");
+});