Completed all exercises in implement directory

Author: A-Moiz

Sprint-2/implement/contains.js

@@ -1,3 +1,15 @@
-function contains() {}
+function contains(object, name) {
+  if (object == null || Object.keys(object).length === 0) {
+    return false;
+  }
+
+  for (let key in object) {
+    if (key === name) {
+      return true;
+    }
+  }
+
+  return false;
+}
 
 module.exports = contains;

Sprint-2/implement/contains.test.js

@@ -20,7 +20,6 @@ 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");
 
 // Given an object with properties
 // When passed to contains with an existing property name
@@ -33,3 +32,15 @@ test.todo("contains on empty object returns false");
 // Given invalid parameters like an array
 // When passed to contains
 // Then it should return false or throw an error
+
+describe("contains", () => {
+  [
+    { input: [{}, "a"], expected: false },
+    { input: [{ a: 1, b: 2 }, "a"], expected: true },
+    { input: [{ a: 1, b: 2 }, "c"], expected: false },
+    { input: [null, "a"], expected: false },
+  ].forEach(({ input, expected }) =>
+    it(`return if object contains the key for ${input[1]}`, () =>
+      expect(contains(...input)).toEqual(expected))
+  );
+});

Sprint-2/implement/lookup.js

@@ -1,5 +1,13 @@
-function createLookup() {
-  // implementation here
+function createLookup(countryCurrencyPairs) {
+  const array = {};
+
+  for (const pair of countryCurrencyPairs) {
+    const country = pair[0];
+    const currency = pair[1];
+    array[country] = currency;
+  }
+
+  return array;
 }
 
 module.exports = createLookup;

Sprint-2/implement/querystring.js

@@ -6,7 +6,8 @@ function parseQueryString(queryString) {
   const keyValuePairs = queryString.split("&");
 
   for (const pair of keyValuePairs) {
-    const [key, value] = pair.split("=");
+    const [key, ...rest] = pair.split("=");
+    const value = rest.join("=");
     queryParams[key] = value;
   }
 

Sprint-2/implement/querystring.test.js

@@ -3,10 +3,23 @@
 // 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",
+describe("parseQueryString", () => {
+  test("returns an empty object when query is empty", () => {
+    expect(parseQueryString("")).toEqual({});
+  });
+
+  test("parses query string values containing =", () => {
+    expect(parseQueryString("equation=x=y+1")).toEqual({
+      equation: "x=y+1",
+    });
+  });
+
+  test("checks for keys without values", () => {
+    expect(parseQueryString("foo&bar=2")).toEqual({
+      foo: "",
+      bar: "2",
+    });
   });
 });

Sprint-2/implement/tally.js

@@ -1,3 +1,19 @@
-function tally() {}
+function tally(itemsList) {
+  const counts = {};
+
+  if (itemsList.length === 0) {
+    return {};
+  }
+
+  if (!Array.isArray(itemsList)) {
+    throw new Error("Input must be an array");
+  }
+
+  for (const item of itemsList) {
+    counts[item] = (counts[item] || 0) + 1;
+  }
+
+  return counts;
+}
 
 module.exports = tally;

Sprint-2/implement/tally.test.js

@@ -32,3 +32,21 @@ test.todo("tally on an empty array returns an empty object");
 // Given an invalid input like a string
 // When passed to tally
 // Then it should throw an error
+
+describe("tally", () => {
+  test("returns an empty object when given an empty array", () => {
+    expect(tally([])).toEqual({});
+  });
+
+  test("returns counts for each unique item", () => {
+    expect(tally(["a", "a", "b", "c"])).toEqual({
+      a: 2,
+      b: 1,
+      c: 1,
+    });
+  });
+
+  test("throws an error when input is not an array", () => {
+    expect(() => tally("abc")).toThrow();
+  });
+});