London | 26-ITP-SEPT | Abakar Souleyman | Sprint 1 | Module-Data-Groups

Sprint-1/fix/median.js

@@ -6,8 +6,27 @@
 // or contains values that aren't numbers (the function is expected to throw - see the tests).
 
 function calculateMedian(list) {
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMedian requires an array of numbers");
+  }
+  if (list.length === 0) {
+    throw new Error("calculateMedian requires a non-empty array");
+  }
+
+  for (const item of list) {
+    if (typeof item !== "number") {
+      throw new Error("calculateMedian requires an array of numbers");
+    }
+  }
+
+  const sortedList = [...list].sort((a, b) => a - b);
   const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
+
+  if (sortedList.length % 2 === 0) {
+    return (sortedList[middleIndex - 1] + sortedList[middleIndex]) / 2;
+  }
+  const median = sortedList.splice(middleIndex, 1)[0];
+
   return median;
 }
 

Sprint-1/implement/dedupe.js

@@ -1 +1,4 @@
-function dedupe() {}
+function dedupe(num) {
+  return [...new Set(num)];
+}
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -1,4 +1,5 @@
 const dedupe = require("./dedupe.js");
+
 /*
 Dedupe Array
 
@@ -16,13 +17,29 @@ E.g. dedupe([1, 2, 1]) returns [1, 2]
 // Given an empty array
 // When passed to the dedupe function
 // Then it should return an empty array
-test.todo("given an empty array, it returns an empty array");
+// test.todo("given an empty array, it returns an empty array");
+test("given an empty array, it returns an empty array", () => {
+  expect(dedupe([])).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("given an array with no duplicates, it returns a copy of the original array", () => {
+  const list = [1, 2, 3];
+
+  const result = dedupe(list);
 
+  expect(result).toEqual([1, 2, 3]);
+  expect(result).not.toBe(list);
+});
 // Given an array of strings or numbers
 // When passed to the dedupe function
-// Then it should return a new array with duplicates removed while preserving the 
+// Then it should return a new array with duplicates removed while preserving the
 // first occurrence of each element from the original array.
+
+test("given an array of strings or numbers, it removes duplicates while preserving the first occurrence", () => {
+  expect(dedupe(["a", "a", "b", "b", "c"])).toEqual(["a", "b", "c"]);
+
+  expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+});

Sprint-1/implement/describe-median.js

@@ -20,6 +20,13 @@ function calculateMedian(list) {
 }
 
 // Implement this function. See describe-median.test.js for the acceptance criteria.
-function describeMedian(list) {}
+function describeMedian(list) {
+  try {
+    const median = calculateMedian(list);
+    return `The median is ${median}`;
+  } catch (error) {
+    return `Could not calculate a median: ${error.message}`;
+  }
+}
 
 module.exports = describeMedian;

Sprint-1/implement/describe-median.test.js

@@ -21,12 +21,27 @@ const describeMedian = require("./describe-median.js");
 // When passed to describeMedian
 // Then it should return "The median is " followed by the median
 // Delete this test.todo and replace it with a test.
-test.todo('given [1, 2, 3], returns "The median is 2"');
+// test.todo('given [1, 2, 3], returns "The median is 2"');
+
+test(`given [1, 2, 3], returns "The median is 2"`, () => {
+  expect(describeMedian([1, 2, 3])).toEqual("The median is 2");
+});
 
 // Given an empty array
 // When passed to describeMedian
 // Then it should return "Could not calculate a median: calculateMedian requires a non-empty array"
 
+test(`given an empty array, returns "Could not calculate a median: calculateMedian requires a non-empty array"
+`, () => {
+  expect(describeMedian([])).toEqual(
+    "Could not calculate a median: calculateMedian requires a non-empty array"
+  );
+});
 // Given something that isn't an array of numbers, e.g. "banana"
 // When passed to describeMedian
 // Then it should return "Could not calculate a median: calculateMedian requires an array of numbers"
+test(`given something that isn't an array of numbers, e.g. "banana", returns "Could not calculate a median: calculateMedian requires an array of numbers"`, () => {
+  expect(describeMedian("banana")).toEqual(
+    "Could not calculate a median: calculateMedian requires an array of numbers"
+  );
+});

Sprint-1/implement/max.js

@@ -1,4 +1,23 @@
 function findMax(elements) {
+  if (!Array.isArray(elements)) {
+    throw new Error("findMax requires an array of numbers");
+  }
+
+  for (const item of elements) {
+    if (typeof item !== "number") {
+      throw new Error("findMax requires an array of numbers");
+    }
+  }
+
+  let max = -Infinity;
+
+  for (const item of elements) {
+    if (item > max) {
+      max = item;
+    }
+  }
+
+  return max;
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,54 @@ const findMax = require("./max.js");
 // When passed to the max function
 // Then it should return -Infinity
 // Delete this test.todo and replace it with a test.
-test.todo("given an empty array, returns -Infinity");
+
+test("given an empty array, returns -Infinity", () => {
+  expect(findMax([])).toBe(-Infinity);
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+test("given an array with one number, returns that number", () => {
+  expect(findMax([7])).toBe(7);
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+test("given an arry with both positive and negative numbers, returns the largest number overall", () => {
+  expect(findMax([-30, 50, -10, -40])).toBe(50);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+test("given an array with just negative numbers, returns the closest one to zero", () => {
+  expect(findMax([-30, -50, -10, -40])).toBe(-10);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
 
+test("given an array with decimal numbers, returns the largest decimal number", () => {
+  expect(findMax([1.5, 2.6, 3.7, 4.8])).toBe(4.8);
+});
 // Given an array containing a value that isn't a number
 // When passed to the max function
 // Then it should throw Error("findMax requires an array of numbers")
-
+test("given an array containing a value that isn't a number, throws an error", () => {
+  expect(() => findMax(["hey", 10, "hi", 60, 10])).toThrow(
+    "findMax requires an array of numbers"
+  );
+});
 // Given something that isn't an array at all, such as "hey", 42 or no argument
 // When passed to the max function
 // Then it should throw Error("findMax requires an array of numbers")
+test(`given something that isn't an array at all,such as "hey", 42 or no argument, throws an error`, () => {
+  expect(() => findMax("hey")).toThrow("findMax requires an array of numbers");
+
+  expect(() => findMax(42)).toThrow("findMax requires an array of numbers");
+
+  expect(() => findMax()).toThrow("findMax requires an array of numbers");
+});

Sprint-1/implement/mean.js

@@ -1,3 +1,23 @@
-function calculateMean(list) {}
+function calculateMean(list) {
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMean requires an array of numbers");
+  }
+
+  if (list.length === 0) {
+    throw new Error("calculateMean requires a non-empty array");
+  }
+
+  let sum = 0;
+
+  for (let i = 0; i < list.length; i++) {
+    if (typeof list[i] !== "number") {
+      throw new Error("calculateMean requires an array of numbers");
+    }
+
+    sum += list[i];
+  }
+
+  return sum / list.length;
+}
 
 module.exports = calculateMean;

Sprint-1/implement/mean.test.js

@@ -23,28 +23,66 @@ const calculateMean = require("./mean.js");
 // When passed to calculateMean
 // Then it should return their mean
 // Delete this test.todo and replace it with a test.
-test.todo("given [1, 2, 6], returns 3");
+
+test("given [1, 2, 6], returns 3", () => {
+  expect(calculateMean([1, 2, 6])).toEqual(3);
+});
 
 // Given an array with a single number
 // When passed to calculateMean
 // Then it should return that number
+test("given an array with a single number, returns that number", () => {
+  expect(calculateMean([1])).toEqual(1);
+});
 
 // Given an array containing negative or decimal numbers
 // When passed to calculateMean
 // Then it should return the correct mean
 
+test("given an array containing negative or decimal numbers, returns the correct mean", () => {
+  expect(calculateMean([10, 2.2, 3.8, -6])).toEqual(2.5);
+});
 // Given an empty array
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires a non-empty array")
-
+test("given an empty array, throws an error", () => {
+  expect(() => calculateMean([])).toThrow(
+    "calculateMean requires a non-empty array"
+  );
+});
 // Given a value that isn't an array, e.g. "banana", 42, null or {}
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
+test(`given a value that isn't an array, e.g. "banana", 42, null or {}, throws an error`, () => {
+  expect(() => calculateMean("banana")).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+
+  expect(() => calculateMean(42)).toThrow(
+    "calculateMean requires an array of numbers"
+  );
 
+  expect(() => calculateMean(null)).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+
+  expect(() => calculateMean({})).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});
 // Given no argument at all
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
-
+test("given no argument at all, throws an error", () => {
+  expect(() => calculateMean()).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});
 // Given an array containing a non-number value, e.g. [1, "2", 3]
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires an array of numbers")
+test(`given an array containing a non-number value, e.g. [1, "2", 3], throws an error`, () => {
+  expect(() => calculateMean([1, "2", 3])).toThrow(
+    "calculateMean requires an array of numbers"
+  );
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,18 @@
 function sum(elements) {
+  if (!Array.isArray(elements)) {
+    throw new Error("sum requires an array of numbers");
+  }
+
+  let total = 0;
+
+  for (let i = 0; i < elements.length; i++) {
+    if (typeof elements[i] !== "number") {
+      throw new Error("sum requires an array of numbers");
+    }
+
+    total += elements[i];
+  }
+  return total;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,42 @@ const sum = require("./sum.js");
 // Given an empty array
 // When passed to the sum function
 // Then it should return 0
-test.todo("given an empty array, returns 0")
+
+test("given an empty array, returns 0", () => {
+  expect(sum([])).toEqual(0);
+});
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
-
+test("given an array with just one number, returns that number", () => {
+  expect(sum([10])).toEqual(10);
+});
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
-
+test("given an array containing negative numbers, returns the correct total sum", () => {
+  expect(sum([10, -20, 30])).toEqual(20);
+});
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
-
+test("given an array with decimal/float numbers, returns the correct total sum", () => {
+  expect(sum([10, 20.5, 30])).toEqual(60.5);
+});
 // Given an array containing a value that isn't a number
 // When passed to the sum function
 // Then it should throw Error("sum requires an array of numbers")
-
+test("given an array containing a value that isn't a number", () => {
+  expect(() => sum(["hey", 10, "hi", 60, 10])).toThrow(
+    "sum requires an array of numbers"
+  );
+});
 // Given something that isn't an array at all, such as "hey", 42 or no argument
 // When passed to the sum function
 // Then it should throw Error("sum requires an array of numbers")
+test(`given something that isn't an array at all, such as "hey", 42 or no argument`, () => {
+  expect(() => sum("hey")).toThrow("sum requires an array of numbers");
+  expect(() => sum(42)).toThrow("sum requires an array of numbers");
+  expect(() => sum()).toThrow("sum requires an array of numbers");
+});

Sprint-1/refactor/includes.js

@@ -1,8 +1,7 @@
 // Refactor the implementation of includes to use a for...of loop
 
 function includes(list, target) {
-  for (let index = 0; index < list.length; index++) {
-    const element = list[index];
+  for (const element of list) {
     if (element === target) {
       return true;
     }