From 809dc28f1c4db251798bf643c8fc643098e29a45 Mon Sep 17 00:00:00 2001
From: abduhasen <abdumussa1363@gmail.com>
Date: Mon, 27 Jul 2026 19:37:01 +0100
Subject: [PATCH 1/4] sprint-2-data-groups-backlog. worked on fixing code and
 writing code based on tdd

---
 Sprint-2/debug/address.js           |  4 ++--
 Sprint-2/debug/author.js            |  9 +++++----
 Sprint-2/debug/recipe.js            |  9 ++++++---
 Sprint-2/implement/contains.js      | 19 ++++++++++++++++++-
 Sprint-2/implement/contains.test.js | 26 ++++++++++++++++++++++++--
 Sprint-2/implement/lookup.js        |  9 +++++++--
 Sprint-2/implement/lookup.test.js   | 28 +++++++++++++++++++++++++++-
 Sprint-2/implement/querystring.js   | 27 +++++++++++++++++++++++++--
 Sprint-2/implement/tally.js         | 18 ++++++++++++++++--
 Sprint-2/implement/tally.test.js    | 24 +++++++++++++++++++++++-
 Sprint-2/interpret/invert.js        | 16 ++++++++++++++++
 11 files changed, 169 insertions(+), 20 deletions(-)

diff --git a/Sprint-2/debug/address.js b/Sprint-2/debug/address.js
index 940a6af83..52f2f8bb8 100644
--- a/Sprint-2/debug/address.js
+++ b/Sprint-2/debug/address.js
@@ -1,5 +1,5 @@
 // Predict and explain first...
-
+//My prediction is that it will log undefined because we used array index to access object value instead of key name.
 // This code should log out the houseNumber from the address object
 // but it isn't working...
 // Fix anything that isn't working
@@ -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..e60f61092 100644
--- a/Sprint-2/debug/author.js
+++ b/Sprint-2/debug/author.js
@@ -1,5 +1,7 @@
 // Predict and explain first...
-
+/* In this code the problem is that the method for...of is used for array 
+   not for object type instead we use for...in this will work through the object
+   and list the key and for value We use author[property] */
 // 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 +12,6 @@ const author = {
   age: 40,
   alive: true,
 };
-
-for (const value of author) {
-  console.log(value);
+for (const values in author) {
+  console.log(`${author[values]}`);
 }
diff --git a/Sprint-2/debug/recipe.js b/Sprint-2/debug/recipe.js
index 6cbdd22cd..baf0f19e5 100644
--- a/Sprint-2/debug/recipe.js
+++ b/Sprint-2/debug/recipe.js
@@ -1,5 +1,6 @@
 // Predict and explain first...
-
+/* My prediction is that on the ingredients didn't used dot notation to access the element that why it will log undefined 
+ instead using for..of loop we can print all the ingredient in new line   */
 // 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 +12,7 @@ const recipe = {
 };
 
 console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+ingredients`);
+for (const ingredient of recipe.ingredients) {
+  console.log(`*${ingredient}`);
+}
diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index cd779308a..56b7375bc 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -1,3 +1,20 @@
-function contains() {}
+function contains(givenObject, keyString) {
+  console.log(givenObject, keyString);
+  if (
+    typeof givenObject !== "object" ||
+    givenObject === null ||
+    Array.isArray(givenObject)
+  ) {
+    return false;
+  }
+  for (const keyProperty in givenObject) {
+    console.log(keyString);
+    if (keyProperty === keyString) {
+      return true;
+    }
+  }
+  return false;
+}
+console.log(contains({ a: 2, b: 1 }, "a"));
 
 module.exports = contains;
diff --git a/Sprint-2/implement/contains.test.js b/Sprint-2/implement/contains.test.js
index 326bdb1f2..dfe02e45a 100644
--- a/Sprint-2/implement/contains.test.js
+++ b/Sprint-2/implement/contains.test.js
@@ -20,16 +20,38 @@ 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("should return false when an empty object is passed to the function", () => {
+  expect(contains({})).toEqual(false);
+});
 
 // Given an object with properties
 // When passed to contains with an existing property name
 // Then it should return true
-
+test("the function should return true when object contains a given property", () => {
+  expect(contains({ a: 1, b: 2, c: 3 }, "c")).toEqual(true);
+  expect(contains({ name: "lee", age: 30 }, "name")).toEqual(true);
+  expect(contains({ place: "spain", city: "madrid", rank: 9 }, "city")).toEqual(
+    true
+  );
+  expect(contains({ zone: 2, zone: 3, zone: 4 }, "zone")).toEqual(true);
+});
 // Given an object with properties
 // When passed to contains with a non-existent property name
 // Then it should return false
+test("the function should return false when property don't exist in the given object", () => {
+  expect(contains({ a: 1, b: 2, c: 3 }, "d")).toEqual(false);
+  expect(contains({ year: 1998, month: 10, Date: 16 }, "age")).toEqual(false);
+  expect(
+    contains({ meal: "pizza", drink: "water", table: 3 }, "starter")
+  ).toEqual(false);
+});
 
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("the function should return false when invalid parameter like an array is passed", () => {
+  expect(contains([10, 23, 34, 45], "3")).toEqual(false);
+  expect(contains("hello", "0")).toEqual(false);
+  expect(contains(["green", "yellow", "rad"], "0")).toEqual(false);
+  expect(contains(((30, 40, 50), 30))).toEqual(false);
+});
diff --git a/Sprint-2/implement/lookup.js b/Sprint-2/implement/lookup.js
index a6746e07f..a14b633d8 100644
--- a/Sprint-2/implement/lookup.js
+++ b/Sprint-2/implement/lookup.js
@@ -1,5 +1,10 @@
-function createLookup() {
+function createLookup(countryCurrencyPairs) {
   // implementation here
+  const currencyPairs = {};
+  for (const innerPair of countryCurrencyPairs) {
+    const [key, value] = innerPair;
+    currencyPairs[key] = value;
+  }
+  return currencyPairs;
 }
-
 module.exports = createLookup;
diff --git a/Sprint-2/implement/lookup.test.js b/Sprint-2/implement/lookup.test.js
index 547e06c5a..575904be5 100644
--- a/Sprint-2/implement/lookup.test.js
+++ b/Sprint-2/implement/lookup.test.js
@@ -1,6 +1,32 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
+test("Function should create an object that have country code as key and country currency code as value", () => {
+  expect(
+    createLookup([
+      ["US", "USD"],
+      ["CA", "CAD"],
+    ])
+  ).toEqual({
+    US: "USD",
+    CA: "CAD",
+  });
+  expect(
+    createLookup([
+      ["BE", "EUR"],
+      ["BR", "BRL"],
+      ["FI", "FIN"],
+    ])
+  ).toEqual({ BE: "EUR", BR: "BRL", FI: "FIN" });
+  expect(
+    createLookup([
+      ["CV", "CPV"],
+      ["CN", "CHN"],
+      ["CR", "CRI"],
+      ["DE", "DEU"],
+      ["IN", "IND"],
+    ])
+  ).toEqual({ CV: "CPV", CN: "CHN", CR: "CRI", DE: "DEU", IN: "IND" });
+});
 
 /*
 
diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 45ec4e5f3..87eee586f 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -6,8 +6,31 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
+    if (pair.length === 0) {
+      continue;
+    } else {
+      const equalityPosition = pair.indexOf("=");
+
+      if (equalityPosition === -1) {
+        queryParams[pair] = "";
+      } else {
+        const key = decodeURIComponent(pair.slice(0, equalityPosition));
+        const replacedKey = key.replace("+", " ");
+
+        const value = decodeURIComponent(pair.slice(equalityPosition + 1));
+        const replacedValue = value.replace("+", " ");
+
+        if (queryParams[replacedKey]) {
+          if (!Array.isArray(queryParams[replacedKey])) {
+            queryParams[replacedKey] = [queryParams[replacedKey]];
+          }
+
+          queryParams[replacedKey].push(replacedValue);
+        } else {
+          queryParams[replacedKey] = replacedValue;
+        }
+      }
+    }
   }
 
   return queryParams;
diff --git a/Sprint-2/implement/tally.js b/Sprint-2/implement/tally.js
index f47321812..9b6a2cbed 100644
--- a/Sprint-2/implement/tally.js
+++ b/Sprint-2/implement/tally.js
@@ -1,3 +1,17 @@
-function tally() {}
-
+function tally(myArray) {
+  if (!Array.isArray(myArray)) {
+    throw "Error";
+  } else if (myArray.length === 0) {
+    return {};
+  }
+  let tallyObject = Object.create(null);
+  for (const singleItems of myArray) {
+    if (tallyObject[singleItems] === undefined) {
+      tallyObject[singleItems] = 1;
+    } else {
+      tallyObject[singleItems] += 1;
+    }
+  }
+  return tallyObject;
+}
 module.exports = tally;
diff --git a/Sprint-2/implement/tally.test.js b/Sprint-2/implement/tally.test.js
index 2ceffa8dd..1627ecd32 100644
--- a/Sprint-2/implement/tally.test.js
+++ b/Sprint-2/implement/tally.test.js
@@ -23,12 +23,34 @@ 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("The function should return empty object when an empty array is passed to the function", () => {
+  expect(tally([])).toEqual({});
+});
 
 // Given an array with duplicate items
 // When passed to tally
 // Then it should return counts for each unique item
+test("The function should return an object where each key is a unique item from the array, and each index is how many times that item duplicate", () => {
+  expect(tally(["a", "a", "a", "b", "b", "b", "c", "c", "c"])).toEqual({
+    a: 3,
+    b: 3,
+    c: 3,
+  });
+  expect(
+    tally(["manchester", "manchester", "london", "london", "leeds"])
+  ).toEqual({ manchester: 2, london: 2, leeds: 1 });
+  expect(tally([1, 1, 2])).toEqual({ 1: 2, 2: 1 });
+  expect(tally(["a"])).toEqual({ a: 1 });
+  expect(tally(["a", "a", "a"])).toEqual({ a: 3 });
+});
 
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+test("The function should throw an error when invalid input is passed", () => {
+  expect(() => {
+    tally("hello");
+  }).toThrow("Error");
+  /*expect(tally(134)).toThrow;
+  expect(tally({ a: 1, b: 3, d: 2 })).toThrow;*/
+});
diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index bb353fb1f..0efb84c7e 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -17,13 +17,29 @@ function invert(obj) {
 }
 
 // a) What is the current return value when invert is called with { a : 1 }
+// the current return value when invert is called with { a:1 } is  { key: 1 }
 
 // b) What is the current return value when invert is called with { a: 1, b: 2 }
+// the current return value  when invert is called with { a: 1, b: 2 } is  { key: 2}
 
 // c) What is the target return value when invert is called with {a : 1, b: 2}
+// the target return value when invert is called with {a : 1, b: 2} is { '1':'a','2':'b'}
 
 // c) What does Object.entries return? Why is it needed in this program?
+// Object.entries is needed because it will gave as the access of the key and value by separating each key value pair.
 
 // d) Explain why the current return value is different from the target output
+/*the current value is different from the targeted value because the for loop already give as access for the key value pairs 
+but when we declare a new object the function where looking the word key in the loop because it was dot notation and taking the 
+word key and pairing it withe the last loop value. */
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
+/*  function invert(obj) {
+     const invertedObj = {};
+
+  for (const [key, value] of Object.entries(obj)) {
+          invertedObj[value] = key;
+    }
+
+  return invertedObj;
+} */

From 03b11158951e06259e1dc04ab2e88dadf61f5df4 Mon Sep 17 00:00:00 2001
From: abduhasen <abdumussa1363@gmail.com>
Date: Wed, 5 Aug 2026 13:13:25 +0100
Subject: [PATCH 2/4] fix codes based on mentor feedback

---
 Sprint-2/implement/contains.js    |  2 --
 Sprint-2/implement/querystring.js |  6 +++---
 Sprint-2/interpret/invert.js      | 34 ++++++++++++++++++++++++-------
 3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/Sprint-2/implement/contains.js b/Sprint-2/implement/contains.js
index 56b7375bc..ecc9b058a 100644
--- a/Sprint-2/implement/contains.js
+++ b/Sprint-2/implement/contains.js
@@ -8,13 +8,11 @@ function contains(givenObject, keyString) {
     return false;
   }
   for (const keyProperty in givenObject) {
-    console.log(keyString);
     if (keyProperty === keyString) {
       return true;
     }
   }
   return false;
 }
-console.log(contains({ a: 2, b: 1 }, "a"));
 
 module.exports = contains;
diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 87eee586f..294657aca 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -15,10 +15,10 @@ function parseQueryString(queryString) {
         queryParams[pair] = "";
       } else {
         const key = decodeURIComponent(pair.slice(0, equalityPosition));
-        const replacedKey = key.replace("+", " ");
+        const replacedKey = key.replace(/\+/g, " ");
 
         const value = decodeURIComponent(pair.slice(equalityPosition + 1));
-        const replacedValue = value.replace("+", " ");
+        const replacedValue = value.replace(/\+/g, " ");
 
         if (queryParams[replacedKey]) {
           if (!Array.isArray(queryParams[replacedKey])) {
@@ -35,5 +35,5 @@ function parseQueryString(queryString) {
 
   return queryParams;
 }
-
+console.log(parseQueryString("key=value1&key=value2&key=value3&foo=bar"));
 module.exports = parseQueryString;
diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index 0efb84c7e..b45e5b63d 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -6,7 +6,7 @@
 
 // E.g. invert({x : 10, y : 20}), target output: {"10": "x", "20": "y"}
 
-function invert(obj) {
+/*function invert(obj) {
   const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
@@ -14,7 +14,7 @@ function invert(obj) {
   }
 
   return invertedObj;
-}
+}*/
 
 // a) What is the current return value when invert is called with { a : 1 }
 // the current return value when invert is called with { a:1 } is  { key: 1 }
@@ -34,12 +34,32 @@ but when we declare a new object the function where looking the word key in the
 word key and pairing it withe the last loop value. */
 
 // e) Fix the implementation of invert (and write tests to prove it's fixed!)
-/*  function invert(obj) {
-     const invertedObj = {};
+function invert(obj) {
+  const invertedObj = {};
 
   for (const [key, value] of Object.entries(obj)) {
-          invertedObj[value] = key;
-    }
+    invertedObj[value] = key;
+  }
 
   return invertedObj;
-} */
+}
+
+function test(description, actual, expected) {
+  if (JSON.stringify(actual) !== JSON.stringify(expected)) {
+    throw new Error(`${description} failed`);
+  }
+}
+test("swapping key and value of the object", invert({ x: 10, y: 20 }), {
+  10: "x",
+  20: "y",
+});
+test("swapping key and value of the object", invert({ x: 10, y: 20, z: 30 }), {
+  10: "x",
+  20: "y",
+  30: "z",
+});
+test("swapping key and value of the object", invert({ x: 10, y: 20, z: 30 }), {
+  x: 10,
+  20: "y",
+  z: 30,
+});

From e9ba1539bc73c01b75636dec60969a2248155c9e Mon Sep 17 00:00:00 2001
From: abduhasen <abdumussa1363@gmail.com>
Date: Wed, 5 Aug 2026 13:27:44 +0100
Subject: [PATCH 3/4] cleaned unnecessary line

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

diff --git a/Sprint-2/implement/querystring.js b/Sprint-2/implement/querystring.js
index 294657aca..db05dbe97 100644
--- a/Sprint-2/implement/querystring.js
+++ b/Sprint-2/implement/querystring.js
@@ -35,5 +35,5 @@ function parseQueryString(queryString) {
 
   return queryParams;
 }
-console.log(parseQueryString("key=value1&key=value2&key=value3&foo=bar"));
+
 module.exports = parseQueryString;

From 91c0de4dd29ada32e3356b293c1fe08f94cbb2ec Mon Sep 17 00:00:00 2001
From: abduhasen <abdumussa1363@gmail.com>
Date: Wed, 5 Aug 2026 16:43:08 +0100
Subject: [PATCH 4/4] fixing test case based on mentor feedback

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

diff --git a/Sprint-2/interpret/invert.js b/Sprint-2/interpret/invert.js
index b45e5b63d..27f2c6495 100644
--- a/Sprint-2/interpret/invert.js
+++ b/Sprint-2/interpret/invert.js
@@ -58,8 +58,8 @@ test("swapping key and value of the object", invert({ x: 10, y: 20, z: 30 }), {
   20: "y",
   30: "z",
 });
-test("swapping key and value of the object", invert({ x: 10, y: 20, z: 30 }), {
-  x: 10,
-  20: "y",
-  z: 30,
+test("swapping key and value of the object", invert({ A: 50, B: 40, D: 30 }), {
+  50: "A",
+  40: "B",
+  30: "D",
 });