From 2baf830ae575af2d229c5205914e65f7bd7916d3 Mon Sep 17 00:00:00 2001
From: Arunkumar Akilan <arunkumarakilanarun@gmail.com>
Date: Tue, 17 Mar 2026 09:13:15 +0000
Subject: [PATCH 1/5] feat: clean Sprint-2 implementation and tests

---
 Sprint-2/debug/address.js              |  2 +-
 Sprint-2/debug/author.js               | 13 +++++++----
 Sprint-2/debug/recipe.js               | 14 +++++++----
 Sprint-2/implement/contains.js         | 20 +++++++++++++++-
 Sprint-2/implement/contains.test.js    | 32 ++++++++++++++++++++++++++
 Sprint-2/implement/lookup.js           | 10 ++++++--
 Sprint-2/implement/lookup.test.js      |  9 ++++++++
 Sprint-2/implement/querystring.js      |  6 +++--
 Sprint-2/implement/querystring.test.js | 15 ++++++++++++
 Sprint-2/implement/tally.js            | 17 +++++++++++++-
 Sprint-2/implement/tally.test.js       |  9 ++++++++
 Sprint-2/interpret/invert.js           | 11 +++++++--
 Sprint-2/interpret/invert.test.js      | 10 ++++++++
 13 files changed, 151 insertions(+), 17 deletions(-)
 create mode 100644 Sprint-2/interpret/invert.test.js

diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..fde180d6d 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -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"]}`);
diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 8c2125977..876962002 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,5 +1,6 @@
 // Predict and explain first...
-
+// The program throws an error because a for...of loop only works with iterable values like arrays or strings. 
+// The author variable is an object, which is not iterable by default, so JavaScript cannot loop through it.
 // 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
 
@@ -10,7 +11,11 @@ const author = {
   age: 40,
   alive: true,
 };
-
-for (const value of author) {
-  console.log(value);
+const values = Object.values(author);
+for(const item of values)
+{
+    console.log(item);
 }
+
+ 
+
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..15a450935 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,6 @@
 // Predict and explain first...
-
+//The title and serves values print correctly because the properties are accessed directly using 
+// recipe.title and recipe.serves.
 // 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?
@@ -10,6 +11,11 @@ const recipe = {
   ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
 };
 
-console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+console.log(`${recipe.title} serves ${recipe.serves}`);
+for(const ingredients of recipe.ingredients)
+{
+  console.log(`*${ingredients}`)
+}
+
+//The program prints the recipe title and number of servings. 
+// Then it loops through the ingredients array and logs each ingredient on a new line so they are displayed individually instead of printing the whole object.
\ No newline at end of file
diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..8cee952a2 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,21 @@
-function contains() {}
+function contains(object, propertyName) {
+    if(typeof object !== 'object' || Array.isArray(object) || object=== null)
+    {
+        throw new Error("It is a invalid object")
+    }
+    const newArray = Object.keys(object);
+    for(let item of newArray)
+    {
+       if (item === propertyName)
+        {
+          return true
+       }
+       
+       
+       
+    }
+    return false;
+}
+
 
 module.exports = contains;
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 326bdb1f2..b64015f11 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -11,6 +11,38 @@ E.g. contains({a: 1, b: 2}, 'c') // returns false
 as the object doesn't contains a key of 'c'
 */
 
+test("An empty object should return false",()=>{
+    const object = {};
+    const propertyName = "a";
+    expect(contains(object, propertyName)).toEqual(false);
+});
+  
+
+test("returns true when the object contains an existing property name", () => {
+  const object = { a: 1, b: 2, c: 3 };
+  const propertyName = "a";
+  expect(contains(object, propertyName)).toEqual(true);
+});
+test("returns false when the object not contains an existing property name", () => {
+  const object = { a: 1, b: 2, c: 3 };
+  const propertyName = "d";
+  expect(contains(object, propertyName)).toEqual(false);
+});
+test("Should throw an error for an invalid parameters", () => {
+  const object = [1,2,3,4,5,6,7];
+  const propertyName = "a";
+  expect(() => contains(object, propertyName)).toThrow();
+});
+test("Should throw an error for an invalid parameters", () => {
+  const object = null;
+  const propertyName = "a";
+  expect(() => contains(object, propertyName)).toThrow();
+});
+test("Should throw an error for an invalid parameters", () => {
+  const object = "hi";
+  const propertyName = "a";
+  expect(() => contains(object, propertyName)).toThrow();
+});
 // Acceptance criteria:
 
 // Given a contains function
diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index a6746e07f..e5f1addc0 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -1,5 +1,11 @@
-function createLookup() {
-  // implementation here
+function createLookup(countryCurrencyPairs) {
+  const countryCurrencyLookup = {};
+
+  for (let item of countryCurrencyPairs) {
+    const [key, value] = [item[0], item[1]];
+   countryCurrencyLookup[key] = value;
+  }
+  return countryCurrencyLookup;
 }
 
 module.exports = createLookup;
diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index 547e06c5a..a1b82e864 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/Sprint-2/implement/lookup.test.js
@@ -2,6 +2,15 @@ const createLookup = require("./lookup.js");
 
 test.todo("creates a country currency code lookup for multiple codes");
 
+test("An array of arrays representing country code and currency code should return an object where the keys are country code values are currency code",()=>{
+  const countryCurrencyPairs = [['IND', 'INR'], ['US', 'USD'], ['UK', 'GBR'], ['CA','CAD'] ];
+ expect(createLookup(countryCurrencyPairs)).toEqual({
+   IND: "INR",
+   US: "USD",
+   UK: "GBR",
+   CA: "CAD",
+ });
+})
 /*
 
 Create a lookup object of key value pairs from an array of code pairs
diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 45ec4e5f3..118a27b53 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -5,8 +5,10 @@ function parseQueryString(queryString) {
   }
   const keyValuePairs = queryString.split("&");
 
-  for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+  for (const item of keyValuePairs) {
+    const pair = item.split("=");
+    const key = pair.shift();
+    const value = pair.join("=");
     queryParams[key] = value;
   }
 
diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 3e218b789..c5681bec4 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -10,3 +10,18 @@ test("parses querystring values containing =", () => {
     "equation": "x=y+1",
   });
 });
+test("An empty string should return an empty object",()=>{
+  expect(parseQueryString("")).toEqual({});
+});
+test("parses querystring parameters with an empty value",()=>{
+  expect(parseQueryString("name=")).toEqual({name :""});
+});
+test("handles querystring parameters that have no = sign",()=>{
+  expect(parseQueryString("flag")).toEqual({flag:""})
+});
+test("parses querystring values containing multiple = characters",()=>{
+  expect(parseQueryString("token=a=b=c=d")).toEqual({token:"a=b=c=d"});
+});
+test("handles multiple querystring parameters when one value contains =",()=>{
+  expect(parseQueryString("a=1&equation=x=y+1")).toEqual({a:"1", equation:"x=y+1"});
+});
diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index f47321812..88ff23bb1 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,3 +1,18 @@
-function tally() {}
+function tally(arr) {
+    const object = {};
+    if(!Array.isArray(arr))
+    {
+        throw new Error("Invalid input: tally expects an array");
+    }
+    if(arr.length === 0)
+    {
+        return object;
+    } 
+    arr.forEach(ele =>{
+        object[ele] =(object[ele] || 0) + 1;
+
+    });
+    return object;
+}
 
 module.exports = tally;
diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 2ceffa8dd..691b622be 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -13,6 +13,15 @@ const tally = require("./tally.js");
  * tally(['a', 'a', 'a']), target output: { a: 3 }
  * tally(['a', 'a', 'b', 'c']), target output: { a : 2, b: 1, c: 1 }
  */
+test("throws an error when the input is not an array", ()=>{
+    expect(()=>tally("hi")).toThrow();
+});
+test("returns an empty object when the input array is empty",()=>{
+    expect(tally([])).toEqual({});
+});
+test("returns the count of each unique item in the array", ()=>{
+    expect(tally(['a','b','a','c','b','a'])).toEqual({a:3,b:2,c:1})
+});
 
 // Acceptance criteria:
 
diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index bb353fb1f..0cdc4da5e 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -9,21 +9,28 @@
 function invert(obj) {
   const invertedObj = {};
 
-  for (const [key, value] of Object.entries(obj)) {
-    invertedObj.key = value;
+  for (const [value, key] of Object.entries(obj)) {
+    invertedObj[key] = value;
   }
 
   return invertedObj;
 }
 
+module.exports = invert;
 // a) What is the current return value when invert is called with { a : 1 }
+//{key:1}
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+//{key:1, key : 2}
 
 // 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?
+// Object.entries() returns an array of [key, value] pairs from an object. It is used here to loop through the object and access both the key and value in each iteration.
 
 // d) Explain why the current return value is different from the target output
+// The return value is different because the program uses dot notation with a variable instead of bracket notation.
+//  Also, the object needs to be inverted, so the key and value must be swapped when iterating through the entries.
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
new file mode 100644
index 000000000..a5d0a564b
--- /dev/null
+++ b/Sprint-2/interpret/invert.test.js
@@ -0,0 +1,10 @@
+const invert = require("./invert");
+
+test("returns an object with the key and value swapped when given a single key-value pair", ()=>{
+  expect(invert({a:1})).toEqual({'1':'a'})
+});
+
+test("returns an object with all keys and values swapped for multiple key-value pairs",()=>{
+
+    expect(invert({a:1, b:2})).toEqual({'1':'a','2':'b'})
+});
\ No newline at end of file

From a149a4c062998ac28872c7d7ca155da82fb00a0e Mon Sep 17 00:00:00 2001
From: Arunkumar Akilan <arunkumarakilanarun@gmail.com>
Date: Mon, 23 Mar 2026 10:14:03 +0000
Subject: [PATCH 2/5] style: format Sprint-2 with Prettier

---
 Sprint-2/debug/author.js               | 10 +++-------
 Sprint-2/debug/recipe.js               | 11 +++++------
 Sprint-2/implement/contains.js         | 25 +++++++++----------------
 Sprint-2/implement/contains.test.js    | 11 +++++------
 Sprint-2/implement/lookup.js           |  2 +-
 Sprint-2/implement/lookup.test.js      | 23 ++++++++++++++---------
 Sprint-2/implement/querystring.test.js | 25 ++++++++++++++-----------
 Sprint-2/implement/tally.js            | 23 ++++++++++-------------
 Sprint-2/implement/tally.test.js       | 12 ++++++------
 Sprint-2/interpret/invert.test.js      | 11 +++++------
 10 files changed, 72 insertions(+), 81 deletions(-)

diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 876962002..0e7093954 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-// The program throws an error because a for...of loop only works with iterable values like arrays or strings. 
+// The program throws an error because a for...of loop only works with iterable values like arrays or strings.
 // The author variable is an object, which is not iterable by default, so JavaScript cannot loop through it.
 // 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
@@ -12,10 +12,6 @@ const author = {
   alive: true,
 };
 const values = Object.values(author);
-for(const item of values)
-{
-    console.log(item);
+for (const item of values) {
+  console.log(item);
 }
-
- 
-
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 15a450935..ef6de51a0 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-//The title and serves values print correctly because the properties are accessed directly using 
+//The title and serves values print correctly because the properties are accessed directly using
 // recipe.title and recipe.serves.
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
@@ -12,10 +12,9 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}`);
-for(const ingredients of recipe.ingredients)
-{
-  console.log(`*${ingredients}`)
+for (const ingredients of recipe.ingredients) {
+  console.log(`*${ingredients}`);
 }
 
-//The program prints the recipe title and number of servings. 
-// Then it loops through the ingredients array and logs each ingredient on a new line so they are displayed individually instead of printing the whole object.
\ No newline at end of file
+//The program prints the recipe title and number of servings.
+// Then it loops through the ingredients array and logs each ingredient on a new line so they are displayed individually instead of printing the whole object.
diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index 8cee952a2..5c5d94b89 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,21 +1,14 @@
 function contains(object, propertyName) {
-    if(typeof object !== 'object' || Array.isArray(object) || object=== null)
-    {
-        throw new Error("It is a invalid object")
+  if (typeof object !== "object" || Array.isArray(object) || object === null) {
+    throw new Error("It is a invalid object");
+  }
+  const newArray = Object.keys(object);
+  for (let item of newArray) {
+    if (item === propertyName) {
+      return true;
     }
-    const newArray = Object.keys(object);
-    for(let item of newArray)
-    {
-       if (item === propertyName)
-        {
-          return true
-       }
-       
-       
-       
-    }
-    return false;
+  }
+  return false;
 }
 
-
 module.exports = contains;
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index b64015f11..79aba2ce1 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -11,12 +11,11 @@ E.g. contains({a: 1, b: 2}, 'c') // returns false
 as the object doesn't contains a key of 'c'
 */
 
-test("An empty object should return false",()=>{
-    const object = {};
-    const propertyName = "a";
-    expect(contains(object, propertyName)).toEqual(false);
+test("An empty object should return false", () => {
+  const object = {};
+  const propertyName = "a";
+  expect(contains(object, propertyName)).toEqual(false);
 });
-  
 
 test("returns true when the object contains an existing property name", () => {
   const object = { a: 1, b: 2, c: 3 };
@@ -29,7 +28,7 @@ test("returns false when the object not contains an existing property name", ()
   expect(contains(object, propertyName)).toEqual(false);
 });
 test("Should throw an error for an invalid parameters", () => {
-  const object = [1,2,3,4,5,6,7];
+  const object = [1, 2, 3, 4, 5, 6, 7];
   const propertyName = "a";
   expect(() => contains(object, propertyName)).toThrow();
 });
diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index e5f1addc0..683a2a9c5 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -3,7 +3,7 @@ function createLookup(countryCurrencyPairs) {
 
   for (let item of countryCurrencyPairs) {
     const [key, value] = [item[0], item[1]];
-   countryCurrencyLookup[key] = value;
+    countryCurrencyLookup[key] = value;
   }
   return countryCurrencyLookup;
 }
diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index a1b82e864..7c2a25575 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/Sprint-2/implement/lookup.test.js
@@ -2,15 +2,20 @@ const createLookup = require("./lookup.js");
 
 test.todo("creates a country currency code lookup for multiple codes");
 
-test("An array of arrays representing country code and currency code should return an object where the keys are country code values are currency code",()=>{
-  const countryCurrencyPairs = [['IND', 'INR'], ['US', 'USD'], ['UK', 'GBR'], ['CA','CAD'] ];
- expect(createLookup(countryCurrencyPairs)).toEqual({
-   IND: "INR",
-   US: "USD",
-   UK: "GBR",
-   CA: "CAD",
- });
-})
+test("An array of arrays representing country code and currency code should return an object where the keys are country code values are currency code", () => {
+  const countryCurrencyPairs = [
+    ["IND", "INR"],
+    ["US", "USD"],
+    ["UK", "GBR"],
+    ["CA", "CAD"],
+  ];
+  expect(createLookup(countryCurrencyPairs)).toEqual({
+    IND: "INR",
+    US: "USD",
+    UK: "GBR",
+    CA: "CAD",
+  });
+});
 /*
 
 Create a lookup object of key value pairs from an array of code pairs
diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index c5681bec4..939c0a0cb 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -3,25 +3,28 @@
 // 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("An empty string should return an empty object",()=>{
+test("An empty string should return an empty object", () => {
   expect(parseQueryString("")).toEqual({});
 });
-test("parses querystring parameters with an empty value",()=>{
-  expect(parseQueryString("name=")).toEqual({name :""});
+test("parses querystring parameters with an empty value", () => {
+  expect(parseQueryString("name=")).toEqual({ name: "" });
 });
-test("handles querystring parameters that have no = sign",()=>{
-  expect(parseQueryString("flag")).toEqual({flag:""})
+test("handles querystring parameters that have no = sign", () => {
+  expect(parseQueryString("flag")).toEqual({ flag: "" });
 });
-test("parses querystring values containing multiple = characters",()=>{
-  expect(parseQueryString("token=a=b=c=d")).toEqual({token:"a=b=c=d"});
+test("parses querystring values containing multiple = characters", () => {
+  expect(parseQueryString("token=a=b=c=d")).toEqual({ token: "a=b=c=d" });
 });
-test("handles multiple querystring parameters when one value contains =",()=>{
-  expect(parseQueryString("a=1&equation=x=y+1")).toEqual({a:"1", equation:"x=y+1"});
+test("handles multiple querystring parameters when one value contains =", () => {
+  expect(parseQueryString("a=1&equation=x=y+1")).toEqual({
+    a: "1",
+    equation: "x=y+1",
+  });
 });
diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index 88ff23bb1..ab9d546ec 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,18 +1,15 @@
 function tally(arr) {
-    const object = {};
-    if(!Array.isArray(arr))
-    {
-        throw new Error("Invalid input: tally expects an array");
-    }
-    if(arr.length === 0)
-    {
-        return object;
-    } 
-    arr.forEach(ele =>{
-        object[ele] =(object[ele] || 0) + 1;
-
-    });
+  const object = {};
+  if (!Array.isArray(arr)) {
+    throw new Error("Invalid input: tally expects an array");
+  }
+  if (arr.length === 0) {
     return object;
+  }
+  arr.forEach((ele) => {
+    object[ele] = (object[ele] || 0) + 1;
+  });
+  return object;
 }
 
 module.exports = tally;
diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 691b622be..e07cdfe03 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -13,14 +13,14 @@ const tally = require("./tally.js");
  * tally(['a', 'a', 'a']), target output: { a: 3 }
  * tally(['a', 'a', 'b', 'c']), target output: { a : 2, b: 1, c: 1 }
  */
-test("throws an error when the input is not an array", ()=>{
-    expect(()=>tally("hi")).toThrow();
+test("throws an error when the input is not an array", () => {
+  expect(() => tally("hi")).toThrow();
 });
-test("returns an empty object when the input array is empty",()=>{
-    expect(tally([])).toEqual({});
+test("returns an empty object when the input array is empty", () => {
+  expect(tally([])).toEqual({});
 });
-test("returns the count of each unique item in the array", ()=>{
-    expect(tally(['a','b','a','c','b','a'])).toEqual({a:3,b:2,c:1})
+test("returns the count of each unique item in the array", () => {
+  expect(tally(["a", "b", "a", "c", "b", "a"])).toEqual({ a: 3, b: 2, c: 1 });
 });
 
 // Acceptance criteria:
diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
index a5d0a564b..813a644b8 100644
--- a/Sprint-2/interpret/invert.test.js
+++ b/Sprint-2/interpret/invert.test.js
@@ -1,10 +1,9 @@
 const invert = require("./invert");
 
-test("returns an object with the key and value swapped when given a single key-value pair", ()=>{
-  expect(invert({a:1})).toEqual({'1':'a'})
+test("returns an object with the key and value swapped when given a single key-value pair", () => {
+  expect(invert({ a: 1 })).toEqual({ 1: "a" });
 });
 
-test("returns an object with all keys and values swapped for multiple key-value pairs",()=>{
-
-    expect(invert({a:1, b:2})).toEqual({'1':'a','2':'b'})
-});
\ No newline at end of file
+test("returns an object with all keys and values swapped for multiple key-value pairs", () => {
+  expect(invert({ a: 1, b: 2 })).toEqual({ 1: "a", 2: "b" });
+});

From 900dfb7df0e816cd336af607f4ac327787b03bcf Mon Sep 17 00:00:00 2001
From: Arunkumar Akilan <arunkumarakilanarun@gmail.com>
Date: Mon, 23 Mar 2026 11:21:50 +0000
Subject: [PATCH 3/5] refactor: improve invert readability by using [key,
 value] destructuring

---
 Sprint-2/interpret/invert.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index 0cdc4da5e..af8f43837 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -9,8 +9,8 @@
 function invert(obj) {
   const invertedObj = {};
 
-  for (const [value, key] of Object.entries(obj)) {
-    invertedObj[key] = value;
+  for (const [key, value ] of Object.entries(obj)) {
+    invertedObj[value] = key;
   }
 
   return invertedObj;

From 3fee122f69da5afa331b57b45749024598fdfd0b Mon Sep 17 00:00:00 2001
From: Arunkumar Akilan <arunkumarakilanarun@gmail.com>
Date: Mon, 23 Mar 2026 11:55:11 +0000
Subject: [PATCH 4/5] feat: complete tally implementation and handle special
 keys like toString

---
 Sprint-2/implement/tally.js      | 2 +-
 Sprint-2/implement/tally.test.js | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index ab9d546ec..f267735da 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,5 +1,5 @@
 function tally(arr) {
-  const object = {};
+  const object = Object.create(null);
   if (!Array.isArray(arr)) {
     throw new Error("Invalid input: tally expects an array");
   }
diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index e07cdfe03..a42cff6b4 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -22,6 +22,9 @@ test("returns an empty object when the input array is empty", () => {
 test("returns the count of each unique item in the array", () => {
   expect(tally(["a", "b", "a", "c", "b", "a"])).toEqual({ a: 3, b: 2, c: 1 });
 });
+test("handles special keys like toString", () => {
+  expect(tally(["toString", "toString"])).toEqual({ "toString": 2 });
+});
 
 // Acceptance criteria:
 
@@ -32,7 +35,7 @@ test("returns the count of each unique item in the array", () => {
 // 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");
+
 
 // Given an array with duplicate items
 // When passed to tally

From 5930937d8c210e7e5ce96d4e7ae1397b4e1315fc Mon Sep 17 00:00:00 2001
From: Arunkumar Akilan <arunkumarakilanarun@gmail.com>
Date: Mon, 23 Mar 2026 12:18:44 +0000
Subject: [PATCH 5/5] test: add edge case tests for parseQueryString and handle
 invalid query pairs

---
 Sprint-2/implement/querystring.js      |  1 +
 Sprint-2/implement/querystring.test.js | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 118a27b53..566456f03 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -9,6 +9,7 @@ function parseQueryString(queryString) {
     const pair = item.split("=");
     const key = pair.shift();
     const value = pair.join("=");
+    if (!key) continue;
     queryParams[key] = value;
   }
 
diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 939c0a0cb..b5571848e 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -28,3 +28,27 @@ test("handles multiple querystring parameters when one value contains =", () =>
     equation: "x=y+1",
   });
 });
+test("ignores pairs with missing key (=b)", () => {
+  expect(parseQueryString("=b")).toEqual({});
+});
+
+test("ignores empty pairs (double &&)", () => {
+  expect(parseQueryString("a=b&&c=d")).toEqual({
+    a: "b",
+    c: "d",
+  });
+});
+test("ignores empty key and value (=)", () => {
+  expect(parseQueryString("=")).toEqual({});
+});
+test("ignores invalid pairs but keeps valid ones", () => {
+  expect(parseQueryString("a=b&=&c=d")).toEqual({
+    a: "b",
+    c: "d",
+  });
+});
+test("keeps key with empty value", () => {
+  expect(parseQueryString("a=")).toEqual({
+    a: "",
+  });
+});
\ No newline at end of file