London | 26-ITP-May | Martin Mwaka | Sprint 2 | Exercises

Sprint-2/debug/address.js

@@ -1,4 +1,5 @@
 // Predict and explain first...
+// [MM] - The original code returns undefined because it is trying to call houseNumber by index, rather than by key.
 
 // 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}`);

Sprint-2/debug/author.js

@@ -1,4 +1,5 @@
 // Predict and explain first...
+// [MM] - The original code does not work because it is trying to loop through an array, rather than an object
 
 // 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) {
+for (const value of Object.values(author)) {
   console.log(value);
 }

Sprint-2/debug/recipe.js

@@ -1,4 +1,5 @@
 // Predict and explain first...
+// [MM] - I expect this programme to log out recipe object rather than the ingredients
 
 // This program should log out the title, how many it serves and the ingredients.
 // Each ingredient should be logged on a new line
@@ -10,6 +11,5 @@ const recipe = {
   ingredients: ["olive oil", "tomatoes", "salt", "pepper"],
 };
 
-console.log(`${recipe.title} serves ${recipe.serves}
-  ingredients:
-${recipe}`);
+console.log(`${recipe.title} serves ${recipe.serves} ingredients:
+${recipe.ingredients.join("\n")}`);

Sprint-2/implement/contains.js

@@ -1,3 +1,13 @@
-function contains() {}
+function contains(object, value) {
+  const isNotObject =
+    typeof object !== "object" || object === null || Array.isArray(object);
+
+  if (isNotObject) return false;
+
+  return Object.hasOwn(object, value);
+}
+
+console.log(contains({ a: 1, b: 2 }, "a"));
+console.log(contains(["a", "b"], "a"));
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -16,20 +16,33 @@ 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 object and a property name, returns true if object contains the property, otherwise return false", () => {
+  expect(contains({ a: 1, b: 2 }, "a")).toBe(true);
+  expect(contains({ a: 1, b: 2 }, "c")).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 returns false", () => {
+  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("given an object and a property name, returns true if object contains the property", () => {
+  expect(contains({ a: 1, b: 2 }, "a")).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 and a property name, returns false if object does not contain the property", () => {
+  expect(contains({ a: 1, b: 2 }, "c")).toBe(false);
+});
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+test("given an invalid array parameter, returns false", () => {
+  expect(contains([1, 2, 3], 3)).toBe(false);
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,84 @@
-function createLookup() {
-  // implementation here
+function createLookup(data) {
+  validateData(data);
+  return data.reduce((lookup, [country, currency]) => {
+    lookup[country] = currency;
+    return lookup;
+  }, {});
 }
 
+// check for valid pairs
+const isValidPair = (value) =>
+  Array.isArray(value) &&
+  value.length === 2 &&
+  typeof value[0] === "string" &&
+  typeof value[1] === "string";
+
+// check for duplicates
+const normaliseDataPair = ([country, currency]) => `${country}|${currency}`;
+const isDuplicated = (data) =>
+  new Set(data.map(normaliseDataPair)).size !== data.length;
+
+const validateData = (data) => {
+  // check that it is an array
+  if (!Array.isArray(data)) {
+    throw new Error("Input must be an array");
+  }
+  // check that input is not empty
+  if (data.length === 0) {
+    throw new Error("Input must not be an empty array");
+  }
+
+  // check that the values are valid
+  if (data.some((value) => !isValidPair(value))) {
+    throw new Error("Input must be valid text pairs");
+  }
+
+  // check for duplicates
+  if (isDuplicated(data)) {
+    throw new Error("Input must not be duplicated");
+  }
+
+  // check country code has 2 uppercase letters
+  if (data.some(([country]) => !/^[A-Z]{2}$/.test(country))) {
+    throw new Error("Country code must be 2 uppercase letters");
+  }
+  // check currency code has 3 uppercase letters
+  if (data.some(([, currency]) => !/^[A-Z]{3}$/.test(currency))) {
+    throw new Error("Currency code must be 3 uppercase letters");
+  }
+};
+
+// Handle invalid cases
+const INVALID_CASES = [
+  [[], "Input must not be an empty array"],
+  ["hello", "Input must be an array"],
+  [[1, 2, 3], "Input must be valid text pairs"],
+  [
+    [
+      ["US", "USD"],
+      ["US", "USD"],
+    ],
+    "Input must not be duplicated",
+  ],
+];
+
+const printInvalidCases = () => {
+  for (const [data, expectedMessage] of INVALID_CASES) {
+    try {
+      createLookup(data);
+      console.log(`Unexpected success for ${JSON.stringify(data)}`);
+    } catch (error) {
+      console.log("-".repeat(50));
+      console.log(
+        `Data: ${JSON.stringify(data)}\nExpected: ${expectedMessage}\nReceived: ${error.message}`
+      );
+    }
+  }
+};
+
+if (require.main === module) {
+  console.log("DATA ERRORS");
+  printInvalidCases();
+  console.log("-".repeat(50));
+}
 module.exports = createLookup;

Sprint-2/implement/lookup.test.js

@@ -1,7 +1,5 @@
 const createLookup = require("./lookup.js");
 
-test.todo("creates a country currency code lookup for multiple codes");
-
 /*
 
 Create a lookup object of key value pairs from an array of code pairs
@@ -33,3 +31,53 @@ It should return:
    'CA': 'CAD'
  }
 */
+
+describe("createLookup", () => {
+  test("maps country codes to currency codes", () => {
+    expect(
+      createLookup([
+        ["US", "USD"],
+        ["CA", "CAD"],
+      ])
+    ).toEqual({
+      US: "USD",
+      CA: "CAD",
+    });
+  });
+
+  test.each([
+    [
+      "throws when input array is empty",
+      [],
+      "Input must not be an empty array",
+    ],
+    ["throws when input is not an array", "hello", "Input must be an array"],
+    [
+      "throws when input pairs are invalid",
+      [1, 2, 3],
+      "Input must be valid text pairs",
+    ],
+    [
+      "throws when duplicate pairs are provided",
+      [
+        ["US", "USD"],
+        ["US", "USD"],
+      ],
+      "Input must not be duplicated",
+    ],
+  ])("%s", (_title, data, expecteMessage) => {
+    expect(() => createLookup(data)).toThrow(expecteMessage);
+  });
+
+  test("throws when country code format is incorrect", () => {
+    expect(() => createLookup([["us", "USD"]])).toThrow(
+      "Country code must be 2 uppercase letters"
+    );
+  });
+
+  test("throws when currency code format is incorrect", () => {
+    expect(() => createLookup([["US", "usd"]])).toThrow(
+      "Currency code must be 3 uppercase letters"
+    );
+  });
+});

Sprint-2/implement/querystring.js

@@ -6,10 +6,22 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
-    queryParams[key] = value;
-  }
+    if (pair === "") continue;
+
+    const [keyPart, ...valueParts] = pair.split("=");
+    const rawKey = keyPart.trim().replace(/\+/g, " ");
+    const rawValue = valueParts.join("=").trim().replace(/\+/g, " ");
+    const key = decodeURIComponent(rawKey);
+    const value = decodeURIComponent(rawValue);
 
+    if (queryParams[key] === undefined) {
+      queryParams[key] = value;
+    } else if (Array.isArray(queryParams[key])) {
+      queryParams[key].push(value);
+    } else {
+      queryParams[key] = [queryParams[key], value];
+    }
+  }
   return queryParams;
 }
 

Sprint-2/implement/querystring.test.js

@@ -3,7 +3,7 @@
 // Below are some test cases the implementation doesn't handle well.
 // Fix the implementation for these tests, 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("should parse values containing '='", () => {
   expect(parseQueryString("equation=a=b-2")).toEqual({
@@ -46,3 +46,17 @@ test("should store values of a key in an array when the key has 2 or more values
     foo: "bar",
   });
 });
+
+test("should return empty object for empty string", () => {
+  expect(parseQueryString("")).toEqual({});
+});
+
+test("should ignore leading and trailing ampersands", () => {
+  expect(parseQueryString("&a=1&b=2&")).toEqual({ a: "1", b: "2" });
+});
+
+test("should parse keys and values with plus signs and percent encoding", () => {
+  expect(parseQueryString("full+name=John+Doe%21")).toEqual({
+    "full name": "John Doe!",
+  });
+});

Sprint-2/implement/tally.js

@@ -1,3 +1,35 @@
-function tally() {}
+function tally(array) {
+  if (!Array.isArray(array)) {
+    throw new Error("Input must be an array");
+  }
+
+  return array.reduce((acc, item) => {
+    acc[item] = (acc[item] ?? 0) + 1;
+    return acc;
+  }, {});
+}
+
+// Handle invalid cases
+const INVALID_CASES = [["hello", "Input must be an array"]];
+
+const printInvalidCases = () => {
+  for (const [data, expectedMessage] of INVALID_CASES) {
+    try {
+      tally(data);
+      console.log(`Unexpected success for ${JSON.stringify(data)}`);
+    } catch (error) {
+      console.log("-".repeat(50));
+      console.log(
+        `Data: ${JSON.stringify(data)}\nExpected: ${expectedMessage}\nReceived: ${error.message}`
+      );
+    }
+  }
+};
+
+if (require.main === module) {
+  console.log("ERROR MESSAGES");
+  printInvalidCases();
+  console.log("-".repeat(50));
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -19,16 +19,28 @@ 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("return counts for each unique item", () => {
+  expect(tally(["a", "b", "c"])).toEqual({ a: 1, b: 1, c: 1 });
+  expect(tally([1, 2, 3])).toEqual({ 1: 1, 2: 1, 3: 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("return counts for each unique item of duplicate items", () => {
+  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("throws when input is not an array", () => {
+  expect(() => tally("hello")).toThrow("Input must be an array");
+});