From 745ed7798fc44f0c530fbafc21ea97b506d96bfe Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Mon, 10 Nov 2025 17:42:25 +0000
Subject: [PATCH 01/31] Predict and explain the code output; fix code where
 needed

---
 Sprint-2/debug/address.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..b036b4802 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,4 +1,5 @@
 // Predict and explain first...
+// when the console.log runs, it will return `My house number is undefined` because `0` is not a key in the object so its value will be undefined
 
 // This code should log out the houseNumber from the address object
 // but it isn't working...
@@ -12,4 +13,4 @@ const address = {
   postcode: "XYZ 123",
 };
 
-console.log(`My house number is ${address[0]}`);
+console.log(`My house number is ${address["houseNumber"]}`);

From b63e8a86e43f9226760f89a2f5e73f973ae99c0b Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Mon, 10 Nov 2025 20:45:37 +0000
Subject: [PATCH 02/31] Predict and explain the output, and modify the loop
 from for...in to for...of

---
 Sprint-2/debug/author.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 8c2125977..969c2ace1 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,4 +1,5 @@
 // Predict and explain first...
+// When the code runs, the console.log will output an error in the terminal because you can not use for...of loop for an object, instead, you use for...in loop
 
 // 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) {
-  console.log(value);
+for (const value in author) {
+  console.log(author[value]);
 }

From 554168fc60010886854df0cfc5e3d038d8878af0 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Tue, 11 Nov 2025 12:09:07 +0000
Subject: [PATCH 03/31] Predict output and fix code to display each ingredient
 value on a new line

---
 Sprint-2/debug/recipe.js | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..e800da778 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+// When the code runs, `${recipe}` part of the console.log expression will output the string `[object Object]`
 // 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 +11,8 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+  ingredients:`);
+
+for (const ingredient of recipe.ingredients) {
+  console.log(ingredient);
+}

From cf6dae41f05ea883a9a1b57ad12aee5e1711fc29 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Wed, 12 Nov 2025 14:09:50 +0000
Subject: [PATCH 04/31] Add 'Answer:' clarification comments for code behavior

---
 Sprint-2/debug/address.js | 2 +-
 Sprint-2/debug/author.js  | 3 ++-
 Sprint-2/debug/recipe.js  | 3 ++-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index b036b4802..9c79c04d9 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-// when the console.log runs, it will return `My house number is undefined` because `0` is not a key in the object so its value will be undefined
+// Answer: when the console.log runs, it will return `My house number is undefined` because `0` is not a key in the object so its value will be undefined
 
 // This code should log out the houseNumber from the address object
 // but it isn't working...
diff --git a/Sprint-2/debug/author.js b/Sprint-2/debug/author.js
index 969c2ace1..f46621c84 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,5 +1,6 @@
 // Predict and explain first...
-// When the code runs, the console.log will output an error in the terminal because you can not use for...of loop for an object, instead, you use for...in loop
+// Answer: When the code runs, the console.log will output an error in the terminal because you can not use for...of loop for an object, 
+// instead, you use for...in loop
 
 // 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
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index e800da778..3ea4fad16 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,6 @@
 // Predict and explain first...
-// When the code runs, `${recipe}` part of the console.log expression will output the string `[object Object]`
+// Answer: When the code runs, `${recipe}` part of the console.log expression will output the string `[object Object]`
+
 // 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?

From 0601e1a14bde664e926bceceaa47d7f2a2d8b941 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Thu, 13 Nov 2025 00:29:05 +0000
Subject: [PATCH 05/31] Add test cases for 'contains' function covering valid,
 empty, and invalid inputs

---
 Sprint-2/implement/contains.test.js | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 326bdb1f2..08f282ec0 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -16,20 +16,40 @@ as the object doesn't contains a key of 'c'
 // 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
+test("Given an input of an object with a property name, returns true if the object contains the property", () => {
+    const objInput = {a: 1};
+    expect(contains(objInput, "a")).toBe(true);
+    expect(contains(objInput, "t")).toBe(false);
+})
 
 // Given an empty object
 // When passed to contains
 // Then it should return false
-test.todo("contains on empty object returns false");
+test("Given an empty object, when passed to contains, returns false", () => {
+    const objInput = {};
+    expect(contains(objInput, "a")).toBe(false);
+})
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
+test("Given an object with properties, when passed to contains with an existing property name, returns true", () => {
+    const objInput = { name: "Alice", age: 25};
+    expect(contains(objInput, "age")).toBe(true);
+})
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("Given an object with properties, when passed to contains with a non-existent property name, returns false", () => {
+    const objInput = { name: "Peter", age: 48};
+    expect(contains(objInput, "gender")).toBe(false);
+})
 
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("Given invalid parameters, when passed to contains, throws an error", () => {
+    const objInput = "hello";
+    expect(() => (contains(objInput, "location"))).toThrow(new TypeError("Invalid input: obj must be a plain object"));
+})
\ No newline at end of file

From d5f1bae2311df0e4c7d6d035b072cc9cb62acb42 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Thu, 13 Nov 2025 00:43:58 +0000
Subject: [PATCH 06/31] Implement 'contains' function:

- returns true if object has property
- returns false if property missing or object empty
- throws TypeError for invalid inputs
---
 Sprint-2/implement/contains.js | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..ba646f695 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,9 @@
-function contains() {}
+function contains(obj, propertyName) {
+    if (typeof(obj) !== "object" || obj === null || Array.isArray(obj)) {
+        throw new TypeError("Invalid input: obj must be a plain object");
+    } 
+
+    return obj.hasOwnProperty(propertyName);
+}
 
 module.exports = contains;

From fbc10ecb08efb29ef63b25058d8da84c5d59539f Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 11:32:26 +0000
Subject: [PATCH 07/31] Add additional tests to each scenario to verify
 'contains' function behaves correctly

---
 Sprint-2/implement/contains.test.js | 57 +++++++++++++++++++++--------
 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 08f282ec0..ecc77b865 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -17,39 +17,64 @@ 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("Given an input of an object with a property name, returns true if the object contains the property", () => {
-    const objInput = {a: 1};
-    expect(contains(objInput, "a")).toBe(true);
-    expect(contains(objInput, "t")).toBe(false);
-})
+  const objInput = { a: 1 };
+  expect(contains(objInput, "a")).toBe(true);
+  expect(contains(objInput, "t")).toBe(false);
+});
 
 // Given an empty object
 // When passed to contains
 // Then it should return false
 test("Given an empty object, when passed to contains, returns false", () => {
-    const objInput = {};
-    expect(contains(objInput, "a")).toBe(false);
-})
+  const objInput = {};
+  expect(contains(objInput, "a")).toBe(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
 test("Given an object with properties, when passed to contains with an existing property name, returns true", () => {
-    const objInput = { name: "Alice", age: 25};
-    expect(contains(objInput, "age")).toBe(true);
-})
+  const objInput = { name: "Alice", age: 25 };
+  expect(contains(objInput, "age")).toBe(true);
+
+  const edgeCaseInput = { 1: "one", "": "empty" };
+  expect(contains(edgeCaseInput, "")).toBe(true);
+});
 
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
 test("Given an object with properties, when passed to contains with a non-existent property name, returns false", () => {
-    const objInput = { name: "Peter", age: 48};
-    expect(contains(objInput, "gender")).toBe(false);
-})
+  const objInput = { name: "Peter", age: 48 };
+  expect(contains(objInput, "gender")).toBe(false);
+
+  const objInput1= { name: "Tayo", age: 10 };
+  expect(contains(objInput1, "location")).toBe(false);
+});
 
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
 test("Given invalid parameters, when passed to contains, throws an error", () => {
-    const objInput = "hello";
-    expect(() => (contains(objInput, "location"))).toThrow(new TypeError("Invalid input: obj must be a plain object"));
-})
\ No newline at end of file
+  expect(() => contains("hello", "location")).toThrow(
+    new TypeError("Invalid input: obj must be a plain object")
+  );
+  expect(() => contains(null, "a")).toThrow(
+    new TypeError("Invalid input: obj must be a plain object")
+  );
+  expect(() => contains(undefined, "a")).toThrow(
+    new TypeError("Invalid input: obj must be a plain object")
+  );
+  expect(() => contains(123, "a")).toThrow(
+    new TypeError("Invalid input: obj must be a plain object")
+  );
+  expect(() => contains(true, "a")).toThrow(
+    new TypeError("Invalid input: obj must be a plain object")
+  );
+  expect(() => contains([], "a")).toThrow(
+    new TypeError("Invalid input: obj must be a plain object")
+  );
+  expect(() => contains(() => {}, "a")).toThrow(
+    new TypeError("Invalid input: obj must be a plain object")
+  );
+});

From 70dc26cdeae25d02cb38419152c8f766750e1f0d Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 11:34:20 +0000
Subject: [PATCH 08/31] Fix indentation inconsistencies in 'contains' function

---
 Sprint-2/implement/contains.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index ba646f695..6431d8884 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,9 +1,9 @@
 function contains(obj, propertyName) {
-    if (typeof(obj) !== "object" || obj === null || Array.isArray(obj)) {
-        throw new TypeError("Invalid input: obj must be a plain object");
-    } 
+  if (typeof obj !== "object" || obj === null || Array.isArray(obj)) {
+    throw new TypeError("Invalid input: obj must be a plain object");
+  }
 
-    return obj.hasOwnProperty(propertyName);
+  return obj.hasOwnProperty(propertyName);
 }
 
 module.exports = contains;

From 829f63d0669578b6a82d4fcf447a7e0947f455df Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 11:51:19 +0000
Subject: [PATCH 09/31] Remove .todo and add unit test for createLookup
 function

---
 Sprint-2/implement/lookup.test.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index 547e06c5a..a536af982 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/Sprint-2/implement/lookup.test.js
@@ -1,6 +1,16 @@
 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 currencyArray = [
+    ["US", "USD"],
+    ["CA", "CAD"],
+  ];
+  const expectedResult = {
+    US: "USD",
+    CA: "CAD",
+  };
+  expect(createLookup(currencyArray)).toEqual(expectedResult);
+});
 
 /*
 

From 0ffc147c262819563cd1d0356efe1d9d2485872e Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 12:17:19 +0000
Subject: [PATCH 10/31] Implement createLookup function to convert array of
 pairs into lookup object

---
 Sprint-2/implement/lookup.js | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index a6746e07f..a8131fd98 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -1,4 +1,10 @@
-function createLookup() {
+function createLookup(arrayLookUp) {
+  const objLookUp = {};
+
+  for (const [country, currency] of arrayLookUp) {
+    objLookUp[country] = currency;
+  }
+  return objLookUp;
   // implementation here
 }
 

From 99df5b64585b6731e06fd880161a99a947f343bf Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 13:05:56 +0000
Subject: [PATCH 11/31] Fix parseQueryString so key-value pairs with '=' in
 values are parsed correctly

---
 Sprint-2/implement/querystring.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 45ec4e5f3..0847324ce 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -6,11 +6,21 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    const index = pair.indexOf("=");
+    let key, value;
+
+    if (index === -1) {
+      key = pair;
+      value = "";
+    } else {
+      key = pair.slice(0, index);
+      value = pair.slice(index + 1);
+    }
     queryParams[key] = value;
   }
 
   return queryParams;
 }
 
+
 module.exports = parseQueryString;

From 60f6d2105ff9625e5ffb30f2cf09047e024168f1 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 13:22:54 +0000
Subject: [PATCH 12/31] Fix parseQueryString to throw TypeError for non-string
 input

---
 Sprint-2/implement/querystring.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 0847324ce..c4f285dbf 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -1,4 +1,7 @@
 function parseQueryString(queryString) {
+  if (typeof queryString !== "string") {
+    throw new TypeError("Invalid input: Input must be a string");
+  }
   const queryParams = {};
   if (queryString.length === 0) {
     return queryParams;

From 7bb207451b7e0188a07bd29bbc873dc1a45cc396 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 13:24:29 +0000
Subject: [PATCH 13/31] Add test cases covering edge cases for parseQueryString

---
 Sprint-2/implement/querystring.test.js | 73 +++++++++++++++++++++++++-
 1 file changed, 71 insertions(+), 2 deletions(-)

diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 3e218b789..6fd81dc19 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -3,10 +3,79 @@
 // 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("handles empty query string", () => {
+  expect(parseQueryString("")).toEqual({});
+});
+
+test("handles empty key", () => {
+  expect(parseQueryString("=value")).toEqual({
+    "": "value",
+  });
+});
+
+test("parses multiple key-value pairs", () => {
+  expect(parseQueryString("a=1&b=2&c=3")).toEqual({
+    a: "1",
+    b: "2",
+    c: "3",
+  });
+});
+
+test("parses values with spaces or special characters", () => {
+  expect(parseQueryString("name=John%20Doe&city=New+York")).toEqual({
+    name: "John%20Doe",
+    city: "New+York",
+  });
+});
+
+test("throws TypeError for non-string input", () => {
+  expect(() => parseQueryString(null)).toThrow(TypeError);
+  expect(() => parseQueryString(null)).toThrow(
+    "Invalid input: Input must be a string"
+  );
+
+  expect(() => parseQueryString(undefined)).toThrow(TypeError);
+  expect(() => parseQueryString(undefined)).toThrow(
+    "Invalid input: Input must be a string"
+  );
+
+  expect(() => parseQueryString(123)).toThrow(TypeError);
+  expect(() => parseQueryString(123)).toThrow(
+    "Invalid input: Input must be a string"
+  );
+
+  expect(() => parseQueryString({})).toThrow(TypeError);
+  expect(() => parseQueryString({})).toThrow(
+    "Invalid input: Input must be a string"
+  );
+});
+
+test("handles repeated keys, last value wins", () => {
+  expect(parseQueryString("a=1&a=2")).toEqual({
+    a: "2",
+  });
+});
+
+test("handles trailing '&'", () => {
+  expect(parseQueryString("a=1&b=2&")).toEqual({
+    a: "1",
+    b: "2",
+    "": "", // empty pair after trailing &
+  });
+});
+
+test("handles leading '&'", () => {
+  expect(parseQueryString("&a=1&b=2")).toEqual({
+    "": "", // empty pair before leading &
+    a: "1",
+    b: "2",
   });
 });

From a2efcdfb49431dadeacab0794bf7c16defb79bab Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 18:48:47 +0000
Subject: [PATCH 14/31] Add test cases for tally function to cover empty input,
 duplicates, and invalid input

---
 Sprint-2/implement/tally.test.js | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 2ceffa8dd..d5a7f02e4 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -19,16 +19,30 @@ 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
+test("tally when passed an array of items, returns an object containing counts for each unique item", () => {
+    expect(tally(["a"])).toEqual({a: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", () => {
+    expect(tally([])).toEqual({});
+});
+
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+test("when an array with duplicate items is passed to tally", () => {
+    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("when an invalid input is passed to tally, throws an error", () => {
+    expect(() => tally("house")).toThrow(
+      new TypeError("Invalid input: Input must be an array")
+    );
+})

From 156dfd953f7b9eba73981f728ab76db768b18083 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 14 Nov 2025 19:51:32 +0000
Subject: [PATCH 15/31] Add function implementation to count array items and
 handle invalid input

---
 Sprint-2/implement/tally.js | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index f47321812..d2bb65861 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,3 +1,19 @@
-function tally() {}
+function tally(arr) {
+  if (!Array.isArray(arr)) {
+    throw new TypeError("Invalid input: Input must be an array");
+  }
+
+  const result = {};
+
+  for (const item of arr) {
+    if (result[item]) {
+      result[item] += 1;
+    } else {
+      result[item] = 1;
+    }
+  }
+
+  return result;
+}
 
 module.exports = tally;

From 1a47dc3a07845b9f5279b9dad5fa23891dabf75e Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sat, 15 Nov 2025 12:09:30 +0000
Subject: [PATCH 16/31] Add answers to questions and fix invert()
 implementation to produce correct output

---
 Sprint-2/interpret/invert.js | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index bb353fb1f..ac505d3f5 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -10,20 +10,22 @@ 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 }
-
+// Answer: { key: 1}
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
-
+// Answer: { key:2}
 // c) What is the target return value when invert is called with {a : 1, b: 2}
-
-// c) What does Object.entries return? Why is it needed in this program?
-
-// d) Explain why the current return value is different from the target output
-
-// e) Fix the implementation of invert (and write tests to prove it's fixed!)
+// Answer: { '1': 'a', '2': 'b' }
+// d) What does Object.entries return? Why is it needed in this program?
+// Object.entries(obj) returns an array of [key, value] pairs, like: [ [ 'a', 1 ], [ 'b', 2 ] ]
+// e) Explain why the current return value is different from the target output
+// Answer: The current return value is different from the target output because `invertedObj.key`
+// uses the literal string "key" instead of the variable key. To use the variable's value as the property name,
+// we must use bracket notation: invertedObj[value] = key.
+// f) Fix the implementation of invert (and write tests to prove it's fixed!)

From 9f60b8bfc420652712b4b4fb36954f0bc4efd531 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sat, 15 Nov 2025 12:32:57 +0000
Subject: [PATCH 17/31] Add test file for invert and test that empty object
 returns empty object; import invert with require

---
 Sprint-2/interpret/invert.test.js | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 Sprint-2/interpret/invert.test.js

diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
new file mode 100644
index 000000000..bf9b47522
--- /dev/null
+++ b/Sprint-2/interpret/invert.test.js
@@ -0,0 +1,6 @@
+const invert = require("./invert.js");
+
+test("Given an empty object, return an empty object", () => {
+    expect(invert({})).toEqual({});
+})
+

From acf14dd51ab2285c696feb728756906cb47ab4ee Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sat, 15 Nov 2025 12:35:04 +0000
Subject: [PATCH 18/31] Add the module.exports statement so the invert function
 can be imported by another file

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

diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index ac505d3f5..f979291bf 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -16,6 +16,8 @@ function invert(obj) {
   return invertedObj;
 }
 
+module.exports = invert;
+
 // a) What is the current return value when invert is called with { a : 1 }
 // Answer: { key: 1}
 // b) What is the current return value when invert is called with { a: 1, b: 2 }

From 92e74343c6bf976bf5f80fb6b52d2436ab8d47be Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sun, 16 Nov 2025 18:22:03 +0000
Subject: [PATCH 19/31] Add test to verify invert returns an empty object for
 empty input

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

diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
index bf9b47522..2da01cd20 100644
--- a/Sprint-2/interpret/invert.test.js
+++ b/Sprint-2/interpret/invert.test.js
@@ -1,6 +1,6 @@
 const invert = require("./invert.js");
 
 test("Given an empty object, return an empty object", () => {
-    expect(invert({})).toEqual({});
-})
+  expect(invert({})).toEqual({});
+});
 

From 7ab4f2da44442cf69b79b717ca8e519acb537f26 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sun, 16 Nov 2025 18:22:34 +0000
Subject: [PATCH 20/31] Add test to verify invert correctly swaps a single
 key-value pair

---
 Sprint-2/interpret/invert.test.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
index 2da01cd20..526a7144a 100644
--- a/Sprint-2/interpret/invert.test.js
+++ b/Sprint-2/interpret/invert.test.js
@@ -4,3 +4,6 @@ test("Given an empty object, return an empty object", () => {
   expect(invert({})).toEqual({});
 });
 
+test("Given a single key-value pair object, returns a swap value", () => {
+  expect(invert({ a: 1 })).toEqual({ 1: "a" });
+});

From c2f3fd2b0fe4c38b18314670bcc0b9a75d4cc86a Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sun, 16 Nov 2025 18:23:11 +0000
Subject: [PATCH 21/31] Add test to verify invert swaps multiple key-value
 pairs

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

diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
index 526a7144a..6b93f771a 100644
--- a/Sprint-2/interpret/invert.test.js
+++ b/Sprint-2/interpret/invert.test.js
@@ -7,3 +7,7 @@ test("Given an empty object, return an empty object", () => {
 test("Given a single key-value pair object, returns a swap value", () => {
   expect(invert({ a: 1 })).toEqual({ 1: "a" });
 });
+
+test("Given multiple key-value pairs object, returns a swap value", () => {
+  expect(invert({ a: 1, b: 2 })).toEqual({ 1: "a", 2: "b" });
+});

From a6a37dcf5d75dbc4ba5ca16d0bff83b225d3d8ae Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sun, 16 Nov 2025 18:46:31 +0000
Subject: [PATCH 22/31] Add test to verify invert throws a TypeError when given
 invalid input

---
 Sprint-2/interpret/invert.test.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
index 6b93f771a..8435e325a 100644
--- a/Sprint-2/interpret/invert.test.js
+++ b/Sprint-2/interpret/invert.test.js
@@ -11,3 +11,9 @@ test("Given a single key-value pair object, returns a swap value", () => {
 test("Given multiple key-value pairs object, returns a swap value", () => {
   expect(invert({ a: 1, b: 2 })).toEqual({ 1: "a", 2: "b" });
 });
+
+test("Given an input that is not a plain object, throws an error", () => {
+  expect(() => invert(null)).toThrowError(
+    new TypeError("Invalid input: Input must be a plain object")
+  );
+});

From abaa0f855223b304ba553fb310dbed7b6f527d78 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sun, 16 Nov 2025 18:49:36 +0000
Subject: [PATCH 23/31] Fix invert to throw an error for non-plain object input

---
 Sprint-2/interpret/invert.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index f979291bf..da315753a 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -8,7 +8,9 @@
 
 function invert(obj) {
   const invertedObj = {};
-
+  if (Object.prototype.toString.call(obj) !== "[object Object]") {
+    throw new TypeError("Invalid input: Input must be a plain object");
+  }
   for (const [key, value] of Object.entries(obj)) {
     invertedObj[value] = key;
   }

From bcdb27009687cb35c9f8a8facc3398866fb9da45 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Sun, 16 Nov 2025 19:32:14 +0000
Subject: [PATCH 24/31] Add additional tests for empty, single, and multiple
 key-value pairs, and nested object input

---
 Sprint-2/interpret/invert.test.js | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/Sprint-2/interpret/invert.test.js b/Sprint-2/interpret/invert.test.js
index 8435e325a..9ce03a6cd 100644
--- a/Sprint-2/interpret/invert.test.js
+++ b/Sprint-2/interpret/invert.test.js
@@ -6,14 +6,42 @@ test("Given an empty object, return an empty object", () => {
 
 test("Given a single key-value pair object, returns a swap value", () => {
   expect(invert({ a: 1 })).toEqual({ 1: "a" });
+  expect(invert({ 1: 1 })).toEqual({ 1: "1" });
+  expect(invert({ key: true })).toEqual({ true: "key" });
 });
 
 test("Given multiple key-value pairs object, returns a swap value", () => {
   expect(invert({ a: 1, b: 2 })).toEqual({ 1: "a", 2: "b" });
+  expect(invert({ 1: "a", 2: "b" })).toEqual({ a: "1", b: "2" });
+  expect(invert({ a: 1, b: "x", c: true })).toEqual({
+    1: "a",
+    x: "b",
+    true: "c",
+  });
+  expect(invert({ a: 1, b: 1 })).toEqual({ 1: "b" });
+  expect(invert({ a: 1, b: 1, c: 1 })).toEqual({ 1: "c" });
 });
 
 test("Given an input that is not a plain object, throws an error", () => {
   expect(() => invert(null)).toThrowError(
     new TypeError("Invalid input: Input must be a plain object")
   );
+  expect(() => invert(undefined)).toThrowError(
+    new TypeError("Invalid input: Input must be a plain object")
+  );
+  expect(() => invert(true)).toThrowError(
+    new TypeError("Invalid input: Input must be a plain object")
+  );
+  expect(() => invert(null)).toThrowError(
+    new TypeError("Invalid input: Input must be a plain object")
+  );
 });
+
+test("handles nested objects and arrays as values", () => {
+  const nestedObj = { a: { x: 1 } };
+  const nestedArray = { b: [1, 2, 3] };
+  // Nested object key becomes "[object Object]"
+  expect(invert(nestedObj)).toEqual({ "[object Object]": "a" });
+  // Array key becomes "1,2,3"
+  expect(invert(nestedArray)).toEqual({ "1,2,3": "b" });
+});
\ No newline at end of file

From 399fbc8ebf0d4d8a41927b12da45018ebe11f19d Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 21 Nov 2025 18:12:20 +0000
Subject: [PATCH 25/31] Use Object.create(null) in tally to avoid inherited
 properties like toString affecting expected results

---
 Sprint-2/implement/tally.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index d2bb65861..65263d045 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -3,7 +3,7 @@ function tally(arr) {
     throw new TypeError("Invalid input: Input must be an array");
   }
 
-  const result = {};
+  const result = Object.create(null);
 
   for (const item of arr) {
     if (result[item]) {

From 368565226d00a199b755d01f79b4e2cbd3cb4379 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 21 Nov 2025 18:17:24 +0000
Subject: [PATCH 26/31] Add test case demonstrating tally must handle items
 like "toString" without prototype conflicts

---
 Sprint-2/implement/tally.test.js | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index d5a7f02e4..ca94edf40 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -20,29 +20,32 @@ const tally = require("./tally.js");
 // When passed an array of items
 // Then it should return an object containing the count for each unique item
 test("tally when passed an array of items, returns an object containing counts for each unique item", () => {
-    expect(tally(["a"])).toEqual({a:1});
-})
+  expect(tally(["a"])).toEqual({ a: 1 });
+});
 
 // Given an empty array
 // When passed to tally
 // Then it should return an empty object
 test("tally on an empty array returns an empty object", () => {
-    expect(tally([])).toEqual({});
+  expect(tally([])).toEqual({});
 });
 
-
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
 test("when an array with duplicate items is passed to tally", () => {
-    expect(tally(["a", "a", "b", "c"])).toEqual({ a: 2, b: 1, c: 1 });
-})
+  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("when an invalid input is passed to tally, throws an error", () => {
-    expect(() => tally("house")).toThrow(
-      new TypeError("Invalid input: Input must be an array")
-    );
-})
+  expect(() => tally("house")).toThrow(
+    new TypeError("Invalid input: Input must be an array")
+  );
+});
+
+test("tally handles items that match inherited object properties", () => {
+  expect(tally(["toString", "toString"])).toEqual({ toString: 2 });
+});

From 5fcad91ddcc3fd952911a6aa4d345e6899f649ee Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 21 Nov 2025 18:42:34 +0000
Subject: [PATCH 27/31] Add conditional decode step for safely handling encoded
 query strings

---
 Sprint-2/implement/querystring.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index c4f285dbf..276093070 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -6,6 +6,11 @@ function parseQueryString(queryString) {
   if (queryString.length === 0) {
     return queryParams;
   }
+
+  if (decodeURI(queryString) === decodeURIComponent(queryString)) {
+    queryString = decodeURIComponent(queryString);
+  }
+
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
@@ -25,5 +30,4 @@ function parseQueryString(queryString) {
   return queryParams;
 }
 
-
 module.exports = parseQueryString;

From 224597c46fb3ee5bea96df22c97d015cb55082a6 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 21 Nov 2025 18:56:32 +0000
Subject: [PATCH 28/31] Add tests to ensure parseQueryString handles encoded
 spaces and special characters

---
 Sprint-2/implement/querystring.test.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Sprint-2/implement/querystring.test.js b/Sprint-2/implement/querystring.test.js
index 6fd81dc19..5086ac04b 100644
--- a/Sprint-2/implement/querystring.test.js
+++ b/Sprint-2/implement/querystring.test.js
@@ -31,9 +31,12 @@ test("parses multiple key-value pairs", () => {
 
 test("parses values with spaces or special characters", () => {
   expect(parseQueryString("name=John%20Doe&city=New+York")).toEqual({
-    name: "John%20Doe",
+    name: "John Doe",
     city: "New+York",
   });
+  expect(parseQueryString("tags%5B%5D=hello%20world")).toEqual({
+    "tags[]": "hello world",
+  });
 });
 
 test("throws TypeError for non-string input", () => {

From 3578991880f7e37a6201ba1971b3aeee2ff7fe30 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 21 Nov 2025 19:00:49 +0000
Subject: [PATCH 29/31] Refactor contains test to remove repetition using a
 loop over invalid inputs

---
 Sprint-2/implement/contains.test.js | 32 +++++++++--------------------
 1 file changed, 10 insertions(+), 22 deletions(-)

diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index ecc77b865..08086d2fa 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -55,26 +55,14 @@ test("Given an object with properties, when passed to contains with a non-existe
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
-test("Given invalid parameters, when passed to contains, throws an error", () => {
-  expect(() => contains("hello", "location")).toThrow(
-    new TypeError("Invalid input: obj must be a plain object")
-  );
-  expect(() => contains(null, "a")).toThrow(
-    new TypeError("Invalid input: obj must be a plain object")
-  );
-  expect(() => contains(undefined, "a")).toThrow(
-    new TypeError("Invalid input: obj must be a plain object")
-  );
-  expect(() => contains(123, "a")).toThrow(
-    new TypeError("Invalid input: obj must be a plain object")
-  );
-  expect(() => contains(true, "a")).toThrow(
-    new TypeError("Invalid input: obj must be a plain object")
-  );
-  expect(() => contains([], "a")).toThrow(
-    new TypeError("Invalid input: obj must be a plain object")
-  );
-  expect(() => contains(() => {}, "a")).toThrow(
-    new TypeError("Invalid input: obj must be a plain object")
-  );
+test("Given invalid parameters, contains throws a TypeError", () => {
+  const invalidInputs = ["hello", null, undefined, 123, true, [], () => {}];
+
+  invalidInputs.forEach(input => {
+    expect(() => contains(input, "a")).toThrow(
+      new TypeError("Invalid input: obj must be a plain object")
+    );
+  });
 });
+
+

From 0f518e295bac81c64defe59020f858bb2f9f6cd4 Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 21 Nov 2025 19:08:48 +0000
Subject: [PATCH 30/31] Replace loop with Array.prototype.join() to print
 ingredients in one console.log

---
 Sprint-2/debug/recipe.js | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 3ea4fad16..5020d1602 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -12,8 +12,5 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:`);
-
-for (const ingredient of recipe.ingredients) {
-  console.log(ingredient);
-}
+  ingredients:
+${recipe.ingredients.join("\n")}`);

From 3f29b47ede95b6cb1835fa082ed24540617fd96b Mon Sep 17 00:00:00 2001
From: iswat <ibeetek@gmail.com>
Date: Fri, 21 Nov 2025 19:53:31 +0000
Subject: [PATCH 31/31] Fix parseQueryString to decode keys and values safely
 after splitting and throw descriptive error for invalid URL encoding

---
 Sprint-2/implement/querystring.js | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 276093070..b496db76c 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -7,10 +7,6 @@ function parseQueryString(queryString) {
     return queryParams;
   }
 
-  if (decodeURI(queryString) === decodeURIComponent(queryString)) {
-    queryString = decodeURIComponent(queryString);
-  }
-
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
@@ -24,6 +20,14 @@ function parseQueryString(queryString) {
       key = pair.slice(0, index);
       value = pair.slice(index + 1);
     }
+
+    try {
+      key = decodeURIComponent(key);
+      value = decodeURIComponent(value);
+    } catch (err) {
+      throw new Error("Invalid URL-encoded string");
+    }
+
     queryParams[key] = value;
   }