Manchester | 25-ITP-Sep | Mahtem T. Mengstu | Sprint 2 |Sprint-2-courseWork

Sprint-2/debug/address.js

@@ -1,5 +1,8 @@
 // Predict and explain first...
 
+ // address is an object, so we can't access it by address[0] like in array we need to use a notation
+// address.houseNumber, address.street, address.city etc ...
+
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
@@ -12,4 +15,9 @@ const address = {
   postcode: "XYZ 123",
 };
 
-console.log(`My house number is ${address[0]}`);
+
+console.log(`My house number is ${address.houseNumber}`);
+
+
+
+// Address.js log function corrected 

Sprint-2/debug/author.js

@@ -1,5 +1,9 @@
 // Predict and explain first...
 
+// I thought the value in the log needed to get attached with the author like value.author 
+// But the error was author is not iterable as it is an object, so we need to modify the for ... of loop as
+// for(const value of Object.values(author))
+
 // 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 +15,8 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of Object.values(author)) {
   console.log(value);
 }
+
+// Author.js corrected.

Sprint-2/debug/recipe.js

@@ -12,4 +12,11 @@ const recipe = {
 
 console.log(`${recipe.title} serves ${recipe.serves}
   ingredients:
-${recipe}`);
+${recipe.ingredients.join("\n")}`);
+
+
+// I guess, because the values of ingredients are given as array, 
+// the way ingredients is passed to the log is not right.   
+
+// recipe.js log function corrected. 
+// recipe.js modified  "${recipe.ingredients.join("\n")}`) to make ingredients appear on new line.

Sprint-2/implement/contains.js

@@ -1,3 +1,19 @@
-function contains() {}
+function contains(obj, key) {
+  if (typeof obj !== "object" || obj === null) {
+    return false;
+  }
+//return key in obj;
+return Object.hasOwn(obj, key);
+
+}
 
 module.exports = contains;
+
+// In contains.js function implemented and tested. 
+
+  let obj = {}, propertyName = "toString";
+  console.log( propertyName in obj );                // true
+  console.log( Object.hasOwn(obj, propertyName) );   // false
+
+  // In contains.js modified return function as return Object.hasOwn(obj, key);
+  // The  "if (typeof obj !== "object" || obj === null)" modified.

Sprint-2/implement/contains.test.js

@@ -17,19 +17,50 @@ as the object doesn't contains a key of 'c'
 // When passed an object and a property name
 // Then it should return true if the object contains the property, false otherwise
 
+test("Should return true when key exists in object", () => {
+  const obj = { a: 1, b: 2 };
+  expect(contains(obj, "a")).toEqual(true);
+});
+
 // Given an empty object
 // When passed to contains
 // Then it should return false
-test.todo("contains on empty object returns false");
+//test.todo("contains on empty object returns false");
+
+test("Should return false when empty object is passed", () => {
+  const obj = {};  // empty object
+  expect(contains(obj, "a")).toEqual(false);
+})
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
 
+test("Should return true when object has the property", () => {
+  const obj = { a: 5, c: 6, r: 5 };
+  expect(contains(obj, "c")).toEqual(true);
+});
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
 
+test("Should return false when object does not have the property", () => {
+  const obj = { a: 5, c: 6, r: 5 };
+  expect(contains(obj, "z")).toEqual(false); // non-existent property name
+});
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+
+test("Should return false when invalid parameters are used", () => {
+  expect(contains([1, 2, 3], "1")).toEqual(true); // "1" is a key
+  expect(contains([1, 2, 3], "3")).toEqual(false); // "3" is not a key
+  //expect(contains([], "a")).toEqual(false);      // array
+  expect(contains(null, "a")).toEqual(false);    // null 
+  expect(contains(5, "a")).toEqual(false);       // number 
+  expect(contains("hello", "a")).toEqual(false); // string 
+})
+
+// In contains.test.js tests for contains.test.js passed 
+
+// contains.test.js re-tested.

Sprint-2/implement/lookup.js

@@ -1,5 +1,27 @@
-function createLookup() {
-  // implementation here
+function createLookup(input) {
+  if (!Array.isArray(input)) {
+    throw new Error("Input must be an array of [country, currency] pairs");
+  }
+
+  const lookup = {};
+
+  for (const pair of input) {
+    if (!Array.isArray(pair) || pair.length !== 2) {
+      throw new Error("Each item must be an array of [country, currency]");
+    }
+
+    const [country, currency] = pair;
+
+    if (typeof country !== "string" || typeof currency !== "string") {
+      throw new Error("Each item must be an array of [country, currency]");
+    }
+
+    lookup[country] = currency;
+  }
+
+  return lookup;
 }
 
 module.exports = createLookup;
+
+// In lookup.js function createLookup implemented. 

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 +33,50 @@ It should return:
    'CA': 'CAD'
  }
 */
+// Case 1: Valid input
+
+test("returns an object with country codes as keys and currency codes as values", () => {
+  const input = [
+    ["US", "USD"],
+    ["CA", "CAD"],
+  ];
+  const expected = { US: "USD", CA: "CAD" };
+
+  expect(createLookup(input)).toEqual(expected);
+});
+
+// Case 2: Empty array
+
+test("returns an empty object when an empty array is passed", () => {
+  expect(createLookup([])).toEqual({});
+});
+
+// Case 3: Input not an array
+
+test("throws an error when input is not an array", () => {
+  expect(() => createLookup("not an array")).toThrow(
+    "Input must be an array of [country, currency] pairs"
+  );
+});
+
+// Case 4: Input null or undefined
+
+test("throws an error when input is null or undefined", () => {
+  expect(() => createLookup(null)).toThrow(
+    "Input must be an array of [country, currency] pairs"
+  );
+  expect(() => createLookup(undefined)).toThrow(
+    "Input must be an array of [country, currency] pairs"
+  );
+});
+
+// Case 5: type of Input elements are not strings 
+
+  test("throws an error if inner array elements are not valid strings", () => {
+    const invalidInput = [['US', 'USD'], ['CA', 123], ['JP', null]];
+    expect(() => createLookup(invalidInput)).toThrow(
+      "Each item must be an array of [country, currency]"
+    );
+  });
+
+// In lookup.test.js test cases added and passed. 

Sprint-2/implement/querystring.js

@@ -1,16 +1,46 @@
 function parseQueryString(queryString) {
-  const queryParams = {};
+  const parsedParams = {}; // Gets the final key-value pairs
+
+  if (!queryString) return parsedParams;
+
+  // Removes leading '?' if present
+
+  if (queryString.startsWith("?")) {
+    queryString = queryString.slice(1);
+  }
+
   if (queryString.length === 0) {
-    return queryParams;
+    return parsedParams;
   }
-  const keyValuePairs = queryString.split("&");
 
-  for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+  // Split the string into individual key-value pairs
+  const pairs = queryString.split("&");
+
+  for (const pair of pairs) {
+    if (!pair) continue; // skip empty segments (like from && or trailing &) eg "name=John&&age=30" 
+
+    const equalSignIndex = pair.indexOf("=");
+
+    let paramKey, paramValue;
+
+    if (equalSignIndex === -1) {
+
+      // If '=' not found we have a key exists but value is empty
+
+      paramKey = decodeURIComponent(pair);
+      paramValue = "";
+    } else {
+      paramKey = decodeURIComponent(pair.slice(0, equalSignIndex));
+      paramValue = decodeURIComponent(pair.slice(equalSignIndex + 1));
+    }
+
+    parsedParams[paramKey] = paramValue; // overwrite previous value if key repeats
   }
 
-  return queryParams;
+  return parsedParams;
 }
 
 module.exports = parseQueryString;
+
+// In querystring.js function implemented. 
+// Decoding of   paramKey = decodeURIComponent(pair); added. 

Sprint-2/implement/querystring.test.js

@@ -10,3 +10,70 @@ test("parses querystring values containing =", () => {
     "equation": "x=y+1",
   });
 });
+
+// Given an empty query string
+
+test("Empty querystring returns empty object", () => {
+  expect(parseQueryString("")).toEqual({});
+});
+
+// A single key with value not given
+
+test("Single Key with No Value", () => {
+  expect(parseQueryString("key=")).toEqual({ key: "" });
+});
+
+// A key without"=" sign 
+
+test("Key Without = Sign", () => {
+  expect(parseQueryString("KeyAlone")).toEqual({ KeyAlone: "" });
+});
+
+// Multiple parameters given
+
+test("Multiple Parameters", () => {
+  expect(parseQueryString("name=Smith&age=40&job=Teacher")).toEqual({
+    name: "Smith",
+    age: "40",
+    job: "Teacher",
+  });
+});
+
+// If values contain special characters
+
+test("Values Containing Special Characters", () => {
+  expect(parseQueryString("query=a%20b%26c%3Dd")).toEqual({ query: "a b&c=d" });
+});
+
+// Query starting with "?"
+
+test("Starting with ?", () => {
+  expect(parseQueryString("?foo=bar")).toEqual({ foo: "bar" });
+});
+
+// Given encoded key eg, %20  to " " 
+
+test("Encoded keys, decoded correctly", () => {
+  expect(parseQueryString("first%20name=John")).toEqual({
+    "first name": "John",
+  });
+});
+
+// Mixed encoded 
+
+test("Mixed encoded and plain parts", () => {
+  expect(parseQueryString("message=Hello%20World%21&Ans=Hello")).toEqual({
+    message: "Hello World!",
+    Ans: "Hello",
+  });
+});
+
+// Ignore  repeated symbols  --- &&
+test("Skips any empty parts that appear because of repeated symbols", () => {
+  expect(parseQueryString("a=1&&b=2")).toEqual({
+    a: "1",
+    b: "2",
+  });
+});
+
+// In querystring.test.js test edge cases added.

Sprint-2/implement/tally.js

@@ -1,3 +1,29 @@
-function tally() {}
+function tally(items) {
+  if (!Array.isArray(items)) {
+    throw new Error("Input must be an array");
+  }
+
+  if (items.length === 0) {
+    return {};
+  }
+
+  const counts = Object.create(null);
+
+  for (const item of items) {
+
+    // Convert objects and arrays to JSON string 
+    const key = (typeof item === "object" && item !== null) ? JSON.stringify(item) : item;
+    counts[key] = (counts[key] || 0) + 1;
+  }
+
+  return counts;
+}
+
+console.log(tally(["toStrin", "toStrin"]));
+console.log(tally(["toString", "toString"]));
 
 module.exports = tally;
+
+// In tally.js function tally() implemented. 
+
+// modification made.