Manchester| 26-ITP-Jan | fonime Edak | Sprint 2 | Data-groups

Sprint-2/debug/address.js

@@ -1,9 +1,8 @@
 // Predict and explain first...
-
+// The code will log undefined because object properties are not accessed by index but through keys
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
-
 const address = {
   houseNumber: 42,
   street: "Imaginary Road",
@@ -12,4 +11,4 @@ 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 +1,6 @@
-// Predict and explain first...
-
+//Predict and explain first...
+// The loop method used is for arrays and not for object literals.
+// for object literals the "in" key word is used to access the keys.
 // 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 +12,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of Object.values(author)) {
   console.log(value);
 }

Sprint-2/debug/recipe.js

@@ -1,15 +1,17 @@
 // Predict and explain first...
-
+// The program cant log the ingredient because the object literal was not reference inside the console.log()
 // 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?
-
+ 
 const recipe = {
   title: "bruschetta",
   serves: 2,
   ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
 };
 
-console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+console.log(`${recipe.title} serves ${recipe.serves}`);
+
+for (const part of recipe.ingredients) {
+  console.log(part);
+}

Sprint-2/implement/contains.js

@@ -1,3 +1,13 @@
-function contains() {}
+function contains(elements, itemKey) {
+  if (!elements) return false;
+  if (typeof elements !== "object" || Array.isArray(elements)) {
+    return false;
+  }
+  if (Object.hasOwn(elements, itemKey)) {
+    return true;
+  }
+
+  return false;
+}
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -13,23 +13,53 @@ as the object doesn't contains a key of 'c'
 
 // Acceptance criteria:
 
-// 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
-
-// Given an empty object
-// When passed to contains
-// Then it should return false
-test.todo("contains on empty object returns false");
-
-// Given an object with properties
-// When passed to contains with an existing property name
-// Then it should return true
-
-// Given an object with properties
-// When passed to contains with a non-existent property name
-// Then it should return false
-
-// Given invalid parameters like an array
-// When passed to contains
-// Then it should return false or throw an error
+describe("contains()", () => {
+  // Given an object with properties
+  // When passed to contains with an existing property name
+  // Then it should return true
+
+  [{ elements: { a: 1, b: 2 }, itemKey: "a", expected: true }].forEach(
+    ({ elements, itemKey, expected }) =>
+      it(` should return ${expected} for key ${itemKey} in ${elements}`, () => {
+        expect(contains(elements, itemKey)).toEqual(expected);
+      })
+  );
+
+  // Given an empty object
+  // When passed to contains
+  // Then it should return false
+
+  [{ elements: {}, itemKey: "c", expected: false }].forEach(
+    ({ elements, itemKey, expected }) =>
+      it(`contains on empty object returns false`, () => {
+        expect(contains(elements, itemKey)).toEqual(expected);
+      })
+  );
+
+  // Given an object with properties
+  // When passed to contains with a non-existent property name
+  // Then it should return false
+
+  [{ elements: { a: 1, b: 2 }, itemKey: "c", expected: false }].forEach(
+    ({ elements, itemKey, expected }) =>
+      it(`When passed to contains with non-existing property name, should return false`, () => {
+        expect(contains(elements, itemKey)).toEqual(expected);
+      })
+  );
+
+  // Given invalid parameters like an array
+  // When passed to contains
+  // Then it should return false or throw an error
+
+  [
+    {
+      elements: [3, 4, 5, "kofoworola", "Evan"],
+      itemKey: 4,
+      expected: false,
+    },
+  ].forEach(({ elements, itemKey, expected }) =>
+    it(`Given invalid parameters it should return false`, () => {
+      expect(contains(elements, itemKey)).toBe(expected);
+    })
+  );
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,14 @@
-function createLookup() {
-  // implementation here
+function createLookup(elements) {
+  if (!Array.isArray(elements) || !elements.every(Array.isArray)) {
+    return "Invalid input";
+  }
+  if (elements.length === 0) return "Invalid input";
+  const lookup = {};
+
+  for (const value of elements) {
+    lookup[value[0]] = value[1];
+  }
+  return lookup;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,6 +1,29 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
+describe("createLookup", () => {
+  [
+    {
+      input: [
+        ["US", "USD"],
+        ["CA", "CAD"],
+        ["NJA", "NGN"],
+        ["RSA", "RND"],
+        ["UK", "GBP"],
+      ],
+      expected: { US: "USD", CA: "CAD", NJA: "NGN", RSA: "RND", UK: "GBP" },
+    },
+  ].forEach(({ input, expected }) =>
+    it(`Should return an object lookup of currency representing country code as keys`, () => {
+      expect(createLookup(input)).toEqual(expected);
+    })
+  );
+  [{ input: ["US", "USD", "CA", "CAD"], expected: "Invalid input" }].forEach(
+    ({ input, expected }) =>
+      it(`should return "Invalid input" for any input not following the input format`, () => {
+        expect(createLookup(input)).toEqual(expected);
+      })
+  );
+});
 
 /*
 

Sprint-2/implement/querystring.js

@@ -3,13 +3,18 @@ function parseQueryString(queryString) {
   if (queryString.length === 0) {
     return queryParams;
   }
+  if (typeof queryString !== "string" || !queryString.includes("="))
+    return "invalid input";
   const keyValuePairs = queryString.split("&");
-
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
-  }
+    const index = pair.indexOf("=");
 
+    if (index !== -1) {
+      const key = pair.slice(0, index);
+      const value = pair.slice(index + 1);
+      queryParams[key] = value;
+    }
+  }
   return queryParams;
 }
 

Sprint-2/implement/querystring.test.js

@@ -3,10 +3,36 @@
 // Below is one test case for an edge case the implementation doesn't handle well.
 // Fix the implementation for this test, and try to think of as many other edge cases as possible - write tests and fix those too.
 
-const parseQueryString = require("./querystring.js")
+const parseQueryString = require("./querystring.js");
 
 test("parses querystring values containing =", () => {
   expect(parseQueryString("equation=x=y+1")).toEqual({
-    "equation": "x=y+1",
+    equation: "x=y+1",
+  });
+});
+
+test("parses querystring values containing duplicate keys", () => {
+  expect(parseQueryString("a=3&a=4&a=1")).toEqual({
+    a: "3",
+    a: "4",
+    a: "1",
+  });
+});
+
+test("parses querystring values containing url encoding cases ", () => {
+  expect(parseQueryString("city=New%20York")).toEqual({
+    city: "New%20York",
+  });
+});
+
+test("parses querystring values containing invalid type", () => {
+  expect(parseQueryString({ "a=1": undefined })).toEqual("invalid input");
+});
+
+test("parses querystring values containing multiple strings", () => {
+  expect(parseQueryString("user=alex&age=16&city=London")).toEqual({
+    user: "alex",
+    age: "16",
+    city: "London",
   });
 });

Sprint-2/implement/tally.js

@@ -1,3 +1,20 @@
-function tally() {}
+function tally(elements) {
+  if (!Array.isArray(elements)) {
+    throw new Error("Invalid input ");
+  }
+  if (elements.length === 0) {
+    return {};
+  }
+  const frequency = Object.create(null);
 
+  for (let i = 0; i < elements.length; i++) {
+    const item = elements[i];
+    if (frequency[item] === undefined) {
+      frequency[item] = 1;
+    } else {
+      frequency[item]++;
+    }
+  }
+  return frequency;
+}
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -15,20 +15,38 @@ const tally = require("./tally.js");
  */
 
 // Acceptance criteria:
+test("should return an object containing the count for each unique item", () => {
+  // Given a function called tally
+  // When passed an array of items
+  // Then it should return an object containing the count for each unique item
 
-// Given a function called tally
-// When passed an array of items
-// Then it should return an object containing the count for each unique item
+  expect(tally(["a", "b", "c", "d", 2, "edak"])).toEqual({
+    a: 1,
+    b: 1,
+    c: 1,
+    d: 1,
+    2: 1,
+    edak: 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", () => {
+  // Given an empty array
+  // When passed to tally
+  // Then it should return 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("it should return counts for each unique item", () => {
+  // Given an array with duplicate items
+  // When passed to tally
+  // Then it should return counts for each unique item
+  expect(tally(["a", "a", "b", "c"])).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("it should throw an error for invalid input", () => {
+  // Given an invalid input like a string
+  // When passed to tally
+  // Then it should throw an error
+  expect(() => tally("ggga")).toThrow("Invalid input");
+});

Sprint-2/interpret/invert.js

@@ -10,20 +10,34 @@ 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 }
 
-// b) What is the current return value when invert is called with { a: 1, b: 2 }
+//const firstCall = invert({ a: 1 });
+//firstCall={key:1}
 
+// b) What is the current return value when invert is called with { a: 1, b: 2 }
+// const secondCall = invert({ a: 1, b: 2 });
+//secondCall={key:2}
 // c) What is the target return value when invert is called with {a : 1, b: 2}
 
+// target value is {1:"a",2:"b"}
+
 // c) What does Object.entries return? Why is it needed in this program?
+//Object.entries() returns an array whose elements are arrays corresponding
+// to the enumerable string-keyed property key-value pairs found directly upon object.
+// It is needed in this program because we want both the object keys and values
 
 // d) Explain why the current return value is different from the target output
+//current about is different from the target about because ofter the loop destructuring
+//  the key and value is assigned  the array element of the objects  the property
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,14 @@
+
+const invert=require('./invert')
+
+test("should swap the keys and values in the object", () => {
+  expect(invert({ x: 10, y: 20 })).toEqual({ 10: "x", 20: "y" });
+});
+
+test("should swap the keys and values in the object", () => {
+  expect(invert({ a: 1 })).toEqual({ 1: "a" });
+});
+
+test("should swap the keys and values in the object", () => {
+  expect(invert({ x: 10, y: 20 })).toEqual({ 10: "x", 20: "y" });
+});