Sheffield | 26-Jan-ITP | Martha Ogunbiyi| Sprint 2| Coursework/sprint 2

Sprint-2/debug/address.js

@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+// ${address[0]} is trying to access a property that does not exist
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
@@ -12,4 +12,4 @@ const address = {
   postcode: "XYZ 123",
 };
 
-console.log(`My house number is ${address[0]}`);
+console.log(`My house number is ${address["houseNumber"]}`);

Sprint-2/debug/author.js

@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+// for...of is trying to iterate a non iterable object
 // This program attempts to log out all the property values in the object.
 // But it isn't working. Explain why first and then fix the problem
 
@@ -11,6 +11,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
-  console.log(value);
+for (const value in author) {
+  console.log(author[value]);
 }

Sprint-2/debug/recipe.js

@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+// ${recipe} is trying to log an object as string and javascript does not have a default conversion of object to string it logs as [object object]
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
 // How can you fix it?
@@ -12,4 +12,4 @@ const recipe = {
 
 console.log(`${recipe.title} serves ${recipe.serves}
   ingredients:
-${recipe}`);
+${recipe.ingredients.join('\n')}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,13 @@
-function contains() {}
+function contains(obj, targetKey) {
+  if (
+    obj === null ||
+    typeof obj !== "object" ||
+    Array.isArray(obj) ||
+    Object.getPrototypeOf(obj) !== Object.prototype
+  ) {
+    throw new Error("Invalid Parameter");
+  }
+  return Object.hasOwn(obj, targetKey);
+}
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -20,16 +20,43 @@ as the object doesn't contains a key of 'c'
 // 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", () => {
+    const input = {};
+    const target = 'a'
+    const result = contains(input, target);
+    expect(result).toBe(false);
+
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+test("Given an object with properties,it should return true", () => {
+    const input = { a: 1, b: 2 };
+    const target = 'a'
+    const result = contains(input, target)
+    expect(result).toBe(true);
+});
+
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("given an object with a non-existent property name, it should return false", () => {
+  const input = { a: 1, b: 2 };
+  const target = 'c'
+  const result = contains(input, target);
+  expect(result).toBe(false);
+});
+
 
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("given an invalid parameters, it should return false or throw an error", () => {
+    const input = ['a', 'b', 'c'];
+    const target = 0;
+    expect(() => contains(input, target)).toThrow();
+
+});
+

Sprint-2/implement/lookup.js

@@ -1,5 +1,11 @@
-function createLookup() {
-  // implementation here
+function createLookup(codeCurrencyArrays) {
+  const result = {};
+
+  for (const [code, currency] of codeCurrencyArrays) {
+    result[code] = currency;
+  }
+
+  return result;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,6 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
+// test.todo("creates a country currency code lookup for multiple codes");
 
 /*
 
@@ -33,3 +33,21 @@ It should return:
    'CA': 'CAD'
  }
 */
+test(
+  "given An array of arrays representing country code and currency code pairs, it should return an object where the keys are the country code", () => {
+    const input = [
+      ["US", "USD"],
+      ["CA", "CAD"],
+      ["NG", "NGN"],
+      ["GP", "GBP"],
+    ];
+    const result = createLookup(input);
+    expect(result).toStrictEqual({
+      US: "USD",
+      CA: "CAD",
+      NG: "NGN",
+      GP: "GBP"
+    })
+  }
+);
+

Sprint-2/implement/querystring.js

@@ -6,11 +6,20 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    if (pair === "") continue; 
+    const index = pair.indexOf("=");
+
+    if (index === -1) {
+      queryParams[pair] = "";
+      continue;
+    }
+    const key = pair.slice(0, index);
+    const value = pair.slice(index + 1);
     queryParams[key] = value;
   }
 
   return queryParams;
 }
 
 module.exports = parseQueryString;
+

Sprint-2/implement/querystring.test.js

@@ -10,3 +10,13 @@ test("parses querystring values containing =", () => {
     "equation": "x=y+1",
   });
 });
+
+
+test("given an empty querystring, it should return an empty object", () => {
+  expect(parseQueryString("")).toEqual({})
+})
+
+test("given a querystring with missing value or no '=' found after the key, it should return empty string value", () => {
+  expect(parseQueryString("a=1&b=&c")).toEqual({ a: "1", b: "", c: "" });
+});
+

Sprint-2/implement/tally.js

@@ -1,3 +1,15 @@
-function tally() {}
+function tally(list) {
+  if (!Array.isArray(list)) {
+    throw new Error("Invalid Parameter");
+  }
+
+  const uniqueItems = Object.create(null);
+
+  for (const item of list) {
+    uniqueItems[item] = (uniqueItems[item] || 0) + 1;
+  }
+
+  return uniqueItems;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -19,16 +19,33 @@ 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("given an array of items, it should return an object containing count for each unique item", () => {
+  const input = ["a", "a", "a"];
+  const result = tally(input);
+  const targetOutput = { a: 3 };
+  expect(result).toEqual(targetOutput);
+});
 
 // 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", () => {
+expect(tally([])).toEqual({})
+});
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+test("given an array of items, it should return an object containing count for each unique item", () => {
+  const input = ["a", "a", "b", "c"];
+  const result = tally(input);
+  const targetOutput = { a: 2, b: 1, c: 1 };
+  expect(result).toEqual(targetOutput);
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("", () => {
+    expect(() => tally("City Dreams")).toThrow();
+});

Sprint-2/interpret/invert.js

@@ -9,21 +9,30 @@
 function invert(obj) {
   const invertedObj = {};
 
+
   for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
+module.exports = invert;
 
 // a) What is the current return value when invert is called with { a : 1 }
+ // returns { key: 1 }
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+ // returns { key: 2 }
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+ // should return {1: a, 2: b}
 
 // c) What does Object.entries return? Why is it needed in this program?
+// Object.entries returns an array of a given object's own enumerable string-keyed property key-value pairs.
+// It is needed to loop through entries in 'obj' 
 
 // d) Explain why the current return value is different from the target output
+//  invertedObj.key = value; is creating a property named 'key' , to access the value stored in 'key' we use the bracket notation without quotes like this invertedObj[key]= value; If the property name comes from a variable → we always use bracket notation without quotes
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+// implementation fixed and test passed 

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,13 @@
+const invert = require("./invert.js");
+
+//Given a function invert()
+//When passed an object 
+//Then it should return a swapped key and value in the object
+// example: Given => {a: 1, b: 2, c: 3}, should return {1: a, 2: b, 3: c}
+
+test("Given an object with at least one key value pair, it should return an inverted key value", () => {
+    const input = { a: 1, b: 2, c: 3 };
+    const output = invert(input);
+    const target = { "1": "a", "2": "b", "3": "c" };
+    expect(output).toEqual(target);
+})