London | 26-ITP-Sept | Diana Ausiejute | Sprint 1 | Sprint-1 Exercises

.gitignore

@@ -4,3 +4,5 @@ node_modules
 **/.DS_Store
 .idea
 package-lock.json
+mean.js
+mean.test.js

Sprint-1/fix/median.js

@@ -6,8 +6,22 @@
 // or contains values that aren't numbers (the function is expected to throw - see the tests).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
+  if (!Array.isArray(list) || !list.every((item) => typeof item === "number")) {
+    throw new Error("calculateMedian requires an array of numbers");
+  }
+
+  if (list.length === 0) {
+    throw new Error("calculateMedian requires a non-empty array");
+  }
+
+  const sortedList = list.slice().sort((a, b) => a - b);
+
+  const mid = Math.floor(sortedList.length / 2);
+  const median =
+    sortedList.length % 2 !== 0
+      ? sortedList[mid]
+      : (sortedList[mid - 1] + sortedList[mid]) / 2;
+
   return median;
 }
 

Sprint-1/implement/dedupe.js

@@ -1 +1,14 @@
-function dedupe() {}
+function dedupe(items) {
+  if (items.length === 0) {
+    return [];
+  }
+
+  let singleOccur = [];
+  items.forEach((i) => {
+    if (!singleOccur.includes(i)) {
+      singleOccur.push(i);
+    }
+  });
+  return singleOccur;
+}
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,13 +16,26 @@ 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("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("should return a copy of the original when the given array has no duplicates", () => {
+  expect(dedupe([1, 3, 8])).toEqual([1, 3, 8]);
+});
 
 // 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("should return a new array with duplicates removed and 1st occurence of each element preserved", () => {
+  expect(dedupe(["Mon", "Wed", "Wed", "Sun", "Tue", "Sun"])).toEqual([
+    "Mon",
+    "Wed",
+    "Sun",
+    "Tue",
+  ]);
+});

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 (err) {
+    return `Could not calculate a median: ${err.message}`;
+  }
+}
 
 module.exports = describeMedian;

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

@@ -21,12 +21,28 @@ 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"');
+describe("describeMedian", () => {
+  test('returns "The median is " followed by the median', () => {
+    expect(describeMedian([3, 1, 4, 1, 5])).toBe("The median is 3");
+  });
+});
 
 // Given an empty array
 // When passed to describeMedian
 // Then it should return "Could not calculate a median: calculateMedian requires a non-empty array"
+test("returns error message when given an empty array", () => {
+  const result = describeMedian([]);
+  expect(result).toBe(
+    "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("returns error message when given a non-array", () => {
+  const result = describeMedian("five seven nine");
+  expect(result).toBe(
+    "Could not calculate a median: calculateMedian requires an array of numbers"
+  );
+});

Sprint-1/implement/max.js

@@ -1,4 +1,17 @@
 function findMax(elements) {
+  if (!Array.isArray(elements)) {
+    throw new Error("findMax requires an array of numbers");
+  }
+
+  if (elements.length === 0) {
+    return -Infinity;
+  }
+
+  if (!elements.every((element) => typeof element === "number")) {
+    throw new Error("findMax requires for all items to be numbers");
+  }
+
+  return Math.max(...elements);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -15,29 +15,59 @@ const findMax = require("./max.js");
 // Given an empty array
 // 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("should return -Infinity if given an empty array", () => {
+  expect(findMax([])).toEqual(-Infinity);
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
 
+test("should return that number if given an array with one number", () => {
+  expect(findMax([2])).toEqual(2);
+});
+
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
 
+test("should return the largest number overall if given positive & negative numbers", () => {
+  expect(findMax([-2, 4, -7, 9])).toEqual(9);
+});
+
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
 
+test("should return the one closest to zero if given only negative numbers", () => {
+  expect(findMax([-2, -4, -7, -9])).toEqual(-2);
+});
+
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
 
+test("should return the largest decimal number when only decimals were given", () => {
+  expect(findMax([-2.5, 4.1, 3.2, 9.3])).toEqual(9.3);
+});
+
 // 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("should throw an error when at least one value is not a number", () => {
+  expect(() => findMax([-2, "9", "sweet", 9])).toThrow(
+    new Error("findMax requires for all items to be 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("should throw an error when the data type isn't an array", () => {
+  expect(() => findMax(["ten", 1, "thirty"])).toThrow(
+    new Error("findMax requires for all items to be numbers")
+  );
+});

Sprint-1/implement/mean.js

@@ -1,3 +1,20 @@
-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");
+  }
+
+  if (!list.every((item) => typeof item === "number")) {
+    throw new Error("calculateMean requires an array of numbers");
+  }
+
+  let sum = list.reduce((a, b) => a + b, 0);
+
+  let meanResult = sum / list.length;
+  return meanResult;
+}
 
 module.exports = calculateMean;

Sprint-1/implement/mean.test.js

@@ -23,28 +23,58 @@ 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");
+describe("calculatemean", () => {
+  it("returns the mean for [1, 2, 6]", () => {
+    expect(calculateMean([1, 2, 6])).toEqual(3);
+  });
+});
 
 // Given an array with a single number
 // When passed to calculateMean
 // Then it should return that number
+it("returns the mean for 3", () => {
+  expect(calculateMean([3])).toEqual(3);
+});
 
 // Given an array containing negative or decimal numbers
 // When passed to calculateMean
 // Then it should return the correct mean
+it("returns the mean for [-1, 2.5, 6]", () => {
+  expect(calculateMean([-1, 2.5, 6])).toEqual(2.5);
+});
 
 // Given an empty array
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires a non-empty array")
+it("throws when given an empty array", () => {
+  expect(() => calculateMean([])).toThrow(
+    new Error("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")
+it("throws when given a non-array", () => {
+  expect(() => calculateMean("luck")).toThrow(
+    new Error("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")
+it("throws when not given any argument", () => {
+  expect(() => calculateMean()).toThrow(
+    new Error("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")
+it("throws when given an array containing a non-number value", () => {
+  expect(() => calculateMean(["two", 5, "8"])).toThrow(
+    new Error("calculateMean requires an array of numbers")
+  );
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,20 @@
 function sum(elements) {
+  if (
+    !Array.isArray(elements) ||
+    !elements.every((item) => typeof item === "number")
+  ) {
+    throw new Error("sum requires an array of numbers");
+  }
+
+  if (elements.length === 0) {
+    return 0;
+  }
+
+  let total = 0;
+  for (let i = 0; i < elements.length; i++) {
+    total += elements[i];
+  }
+  return total;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -13,24 +13,45 @@ 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("should return the same number when given one number", () => {
+  expect(sum([3])).toEqual(3);
+});
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+test("should return correct sum when given negative numbers", () => {
+  expect(sum([5, -4, 1, 9])).toEqual(11);
+});
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+test("should return a correct total sum when given decimal/float numbers", () => {
+  expect(sum([2.2, 1, 4.1])).toEqual(7.3);
+});
 
 // 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("should throw an error when passing non-number values", () => {
+  expect(() => sum([8, -3, ""])).toThrow(
+    new Error("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("should throw an error when passing non-array data types", () => {
+  expect(() => sum("three", {})).toThrow(
+    new Error("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;
     }