LONDON | MAY-2025 | HAKAN MURAT KAVUT | MODULE DATA-GROUPS SPRINT-2

Sprint-2/debug/address.js

@@ -3,6 +3,8 @@
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
+// address is not an array so the index can't use to retrieve data from address object.
+// We should use key value of object like address.houseNumber or address["houseNumber"].
 
 const address = {
   houseNumber: 42,
@@ -12,4 +14,4 @@ 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

@@ -3,6 +3,9 @@
 // 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
 
+// At the first, for loop syntax is not correct. We should use "in" instead of "of".
+// Then to retrieve property value of property, we should use [].
+
 const author = {
   firstName: "Zadie",
   lastName: "Smith",
@@ -11,6 +14,6 @@ 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

@@ -4,12 +4,16 @@
 // Each ingredient should be logged on a new line
 // How can you fix it?
 
+// There is a recipe object and inside the recipe, ingredient property is an array.
+// We should use for loop to log out the ingredients. 
+
 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}`+'\n'+'Ingredients:');
+for (const ingredient of recipe.ingredients) {
+  console.log(`- ${ingredient}`);
+}

Sprint-2/implement/contains.js

@@ -1,3 +1,9 @@
-function contains() {}
+function contains(list, prop) {
+  return (
+    typeof list === "object" &&
+    !Array.isArray(list) &&
+    list[prop] != null
+  );
+}
 
-module.exports = contains;
+module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -12,24 +12,61 @@ as the object doesn't contains a key of 'c'
 */
 
 // Acceptance criteria:
+describe("find contains", () => {
+  // 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
+  it("the object contains the property, returns true", () => {
+    const list = { a: 1, b: 2 };
+    let prop = "a";
+    const result = contains(list, prop);
+    expect(result).toEqual(true);
+  });
 
-// 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
+  it("the object does not contain the property, returns false", () => {
+    const list = { a: 1, b: 2 };
+    let prop = "c";
+    const result = contains(list, prop);
+    expect(result).toEqual(false);
+  });
 
-// Given an empty object
-// When passed to contains
-// Then it should return false
-test.todo("contains on empty object returns false");
+  // Given an empty object
+  // When passed to contains
+  // Then it should return false
+  it("contains on empty object returns false", () => {
+    const list = {};
+    let prop = "a";
+    const result = contains(list, prop);
+    expect(result).toEqual(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 an existing property name
+  // Then it should return true
+  it("the property is contained returns true", () => {
+    const list = { x: 10, y: 20 };
+    let prop = "y";
+    const result = contains(list, prop);
+    expect(result).toEqual(true);
+  });
 
-// Given an object with properties
-// When passed to contains with a non-existent property name
-// Then it should return false
+  // Given an object with properties
+  // When passed to contains with a non-existent property name
+  // Then it should return false
+  it("contains returns false when the property does not exist", () => {
+    const list = { x: 10, y: 20 };
+    let prop = "z";
+    const result = contains(list, prop);
+    expect(result).toEqual(false);
+  });
 
-// Given invalid parameters like an array
-// When passed to contains
-// Then it should return false or throw an error
+  // Given invalid parameters like an array
+  // When passed to contains
+  // Then it should return false or throw an error
+  it("returns false when the input is not an object (array)", () => {
+    const list = ["a", "b", "c"];
+    let prop = "a";
+    const result = contains(list, prop);
+    expect(result).toEqual(false);
+  });
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,11 @@
-function createLookup() {
-  // implementation here
+function createLookup(countryCurrencyPairs) {
+  const queryParams = {};
+  for (const item of countryCurrencyPairs) {
+    const key = item[0];
+    const value = item[1];
+    queryParams[key] = value;
+  }
+  return queryParams;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -33,3 +33,27 @@ It should return:
    'CA': 'CAD'
  }
 */
+
+// Acceptance criteria:
+describe("creates a country currency code lookup for multiple codes", () => {
+  it("the object contains the property, returns true", () => {
+    const countryCurrencyPairs = [
+      ["US", "USD"],
+      ["CA", "CAD"],
+    ];
+    let expected = { US: "USD", CA: "CAD" };
+    const result = createLookup(countryCurrencyPairs);
+    expect(result).toEqual(expected);
+  });
+
+  it("the object contains the three properties, returns true", () => {
+    const countryCurrencyPairs = [
+      ["TR", "TRY"],
+      ["JP", "JPY"],
+      ["DK", "DKK"],
+    ];
+    let expected = { TR: "TRY", JP: "JPY", DK: "DKK" };
+    const result = createLookup(countryCurrencyPairs);
+    expect(result).toEqual(expected);
+  });
+});

Sprint-2/implement/querystring.js

@@ -3,10 +3,12 @@ function parseQueryString(queryString) {
   if (queryString.length === 0) {
     return queryParams;
   }
-  const keyValuePairs = queryString.split("&");
+  const keyValuePairs = queryString.split(",");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    const [rawKey, ...rawValueParts] = pair.split("=");
+    const key = decodeURIComponent(rawKey || "");
+    const value = decodeURIComponent(rawValueParts.join("=") || "");
     queryParams[key] = value;
   }
 

Sprint-2/implement/querystring.test.js

@@ -10,3 +10,9 @@ test("parses querystring values containing =", () => {
     "equation": "x=y+1",
   });
 });
+
+test("parses querystring values containing =", () => {
+  expect(parseQueryString("equation=x=y+1")).toEqual({
+    "equation": "x=y+1",
+  });
+});

Sprint-2/implement/tally.js

@@ -1,3 +1,10 @@
-function tally() {}
+function tally(input) {
+  if(!Array.isArray(input)) throw new Error("Input is not valid.");;
+  const queryParams = {};
+  for (const char of input) {
+    queryParams[char] = queryParams[char] !== undefined ? queryParams[char] +1 : 1;
+  }
+  return queryParams;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -19,16 +19,49 @@ 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
+describe("take a list of items and count the frequency of each item", () => {
+  [
+    { input: ["a"], expected: { a: 1 }},
+    { input: ["a", "a", "a"], expected:  { a: 3 } },
+    { input: ["a", "a", "b", "c"], expected: { a : 2, b: 1, c: 1 }},
+  ].forEach(({ input, expected }) =>
+    it(`returns an object`, () => expect(tally(input)).toEqual(expected))
+  );
+});
 
 // 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");
+it("tally on an empty array returns an empty object", () => {
+    const input = [];
+    const result = tally(input);
+    expect(result).toEqual({});
+  });
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
-
+describe("take a list of items and count the frequency of duplicate items", () => {
+  [
+    { input: ["a"], expected: { a: 1 }},
+    { input: ["a", "b", "c", "a", "b", "c"], expected:  { a: 2, b:2, c:2 } },
+    { input: ["a", "a", "b", "c","a", "a", "b", "c"], expected: { a : 4, b: 2, c: 2 }},
+    { input: ["apple", "banana", "apple", "orange", "banana", "apple"], expected: { apple: 3, banana: 2, orange: 1 } },
+  ].forEach(({ input, expected }) =>
+    it(`returns correct counts for input which are duplicated`, () => expect(tally(input)).toEqual(expected))
+  );
+});
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+describe("an invalid input like string, number, boolean or object", () => {
+  [
+    { input: 5 },
+    { input: "Hello" },
+    { input: true },
+    { input: { a: 2, b: 1, c: 1 } },
+  ].forEach(({ input }) =>
+    it(`tally should throw an error for input is not array }`, () =>
+      expect(() => tally(input)).toThrow("Input is not valid."))
+  );
+});

Sprint-2/interpret/invert.js

@@ -10,20 +10,24 @@ function invert(obj) {
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+    invertedObj[value] = key;
   }
 
   return invertedObj;
 }
 
-// a) What is the current return value when invert is called with { a : 1 }
+module.exports = invert;
 
+// a) What is the current return value when invert is called with { a : 1 }
+// {"1":"a"}
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
-
+// {"1":"a" , "2":"b"}
 // c) What is the target return value when invert is called with {a : 1, b: 2}
-
+// {"1":"a" , "2":"b"}
 // c) What does Object.entries return? Why is it needed in this program?
-
+// entries method used for converting the object to an array object as key, value pair.
 // d) Explain why the current return value is different from the target output
-
+// current return value is actual return of function and target output is expected.
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+// I created separated test file
+

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,18 @@
+const invert = require("./invert.js");
+
+describe("creates a invert object", () => {
+  it("the object contains one key, value pair", () => {
+    const obj = { a : 1 };
+    let expected = {"1":"a"};
+    const result = invert(obj);
+    expect(result).toEqual(expected);
+  });
+
+  it("the object contains the two pairs", () => {
+    const obj = { a: 1, b: 2 };
+    let expected = {"1":"a" , "2":"b"};
+    const result = invert(obj);
+    expect(result).toEqual(expected);
+  });
+});
+