Birmingham | 26-ITP-Jan | Tasleem Adedokun | Sprint 2 | Data group-coursework

Sprint-2/debug/address.js

@@ -1,5 +1,8 @@
 // Predict and explain first...
 
+// The result will be undefine. The reason we are trying to get an information using an array index method for and object.
+
+
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
@@ -12,4 +15,4 @@ 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 +1,8 @@
 // Predict and explain first...
 
+//The for...of loop only works on iterable objects, like arrays, strings, Maps, Sets.
+
+
 // 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 +14,6 @@ const author = {
   alive: true,
 };
 
-for (const value of author) {
+for (const value of Object.values (author)) {
   console.log(value);
 }

Sprint-2/debug/recipe.js

@@ -1,5 +1,7 @@
 // Predict and explain first...
 
+// This is trying to print the whole object (recipe) instead of the ingredients array.
+
 // 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?
@@ -11,5 +13,5 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+ingredients:
+${recipe.ingredients.join("\n")}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,11 @@
-function contains() {}
+function contains(obj, prop) {
+  // Check that obj is an object (not null) and not an array
+  if (typeof obj !== "object" || obj === null || Array.isArray(obj)) {
+    return false;
+  }
+  // Check if the property exists directly on the object
+ return Object.hasOwn(obj, prop);
+}
+
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -20,16 +20,32 @@ 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("returns false for empty object", () => {
+  expect(contains({}, "a")).toBe(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
-
+test("returns true for existing property", () => {
+  const obj = { a: 1, b: 2 };
+  expect(contains(obj, "a")).toBe(true);
+  expect(contains(obj, "b")).toBe(true);
+});
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("returns false for non-existent property", () => {
+  const obj = { a: 1, b: 2 };
+  expect(contains(obj, "c")).toBe(false);
+});
 
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("returns false for invalid inputs", () => {
+  expect(contains([1, 2, 3], "0")).toBe(false);
+  expect(contains(null, "a")).toBe(false);
+  expect(contains(undefined, "a")).toBe(false);
+  expect(contains("string", "length")).toBe(false);
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,23 @@
-function createLookup() {
+
   // implementation here
+  function createLookup(pairs) {
+
+  if (!Array.isArray(pairs)) {
+    throw new Error('Input must be an array of pairs');
+  }
+
+  const lookup = {};
+
+  for (const pair of pairs) {
+
+    if (!Array.isArray(pair) || pair.length !== 2) {
+      throw new Error('Each element must be an array of [countryCode, currencyCode]');
+    }
+    const [country, currency] = pair;
+    lookup[country] = currency;
+  }
+
+  return lookup;
 }
 
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,7 +1,18 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
-
+test("creates a country currency code lookup for multiple codes", () => {
+  const input = [
+    ["US", "USD"],
+    ["CA", "CAD"],
+  ];
+
+  const expected = {
+    US: "USD",
+    CA: "CAD",
+  };
+
+  expect(createLookup(input)).toEqual(expected);
+});
 /*
 
 Create a lookup object of key value pairs from an array of code pairs

Sprint-2/implement/querystring.js

@@ -1,12 +1,13 @@
 function parseQueryString(queryString) {
   const queryParams = {};
-  if (queryString.length === 0) {
+  if (!queryString || queryString.length === 0) {
     return queryParams;
   }
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    const [key, ...rest] = pair.split("=");
+    const value = rest.join("="); // this join back the remaining parts
     queryParams[key] = value;
   }
 

Sprint-2/implement/querystring.test.js

@@ -10,3 +10,20 @@ test("parses querystring values containing =", () => {
     "equation": "x=y+1",
   });
 });
+
+test("parses multiple query params", () => {
+  expect(parseQueryString("a=1&b=2")).toEqual({
+    a: "1",
+    b: "2",
+  });
+});
+
+test("handles key with no value", () => {
+  expect(parseQueryString("a=")).toEqual({
+    a: "",
+  });
+});
+
+test("returns empty object for empty string", () => {
+  expect(parseQueryString("")).toEqual({});
+});

Sprint-2/implement/tally.js

@@ -1,3 +1,15 @@
-function tally() {}
+function tally(items) {
+  if (!Array.isArray(items)) {
+    throw new Error("Input must be an array");
+  }
+
+  const result = Object.create(null);
+
+  for (const item of items) {
+    result[item] = (result[item] || 0) + 1;
+  }
+
+  return result;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -23,12 +23,24 @@ const tally = require("./tally.js");
 // 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("returns counts for each unique item when array has duplicates", () => {
+  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("throws an error for invalid input like a string", () => {
+  expect(() => tally("abc")).toThrow("Input must be an array");
+});

Sprint-2/interpret/invert.js

@@ -8,22 +8,43 @@
 
 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 }
+console.log(invert({ a: 1 }));
+//Result: { key: 1 }
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+console.log(invert({ a: 1, b: 2 }));
+// Result: { key: 2 }
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
 
+console.log(invert({ a: 1, b: 2 }));
+// Result should be{"1": a, "2":"b"}
+
 // c) What does Object.entries return? Why is it needed in this program?
 
+// It takes an object and returns an array of key-value pairs, where each pair is itself an array:
+const obj = { a: 1, b: 2 };
+console.log(Object.entries(obj));
+//Result:[ [ 'a', 1 ], [ 'b', 2 ] ]
+
 // d) Explain why the current return value is different from the target output
 
+// The line invertedObj.key = value; creates a "key" and assign the value to it. With variables, we need to use bracket notation and dot notation.
+
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+
+// After fixing the code i ran node and got the following accordingly:
+//{ '1': 'a' }
+//{ '1': 'a', '2': 'b' }
+//{ '1': 'a', '2': 'b' }
+//[ [ 'a', 1 ], [ 'b', 2 ] ]
+
+
+module.exports = invert;

Sprint-2/interpret/invert.test.js

@@ -0,0 +1,23 @@
+const invert = require('./invert');
+test("inverts a single key-value pair", () => {
+  expect(invert({ a: 1 })).toEqual({ 1: "a" });
+});
+
+test("inverts multiple key-value pairs", () => {
+  expect(invert({ a: 1, b: 2 })).toEqual({ 1: "a", 2: "b" });
+});
+
+test("handles string values", () => {
+  expect(invert({ x: "orange", y: "grape" })).toEqual({
+    orange: "x",
+    grape: "y",
+  });
+});
+
+test("returns empty object when input is empty", () => {
+  expect(invert({})).toEqual({});
+});
+
+test("overwrites duplicate values (last key wins)", () => {
+  expect(invert({ a: 1, b: 1 })).toEqual({ 1: "b" });
+});