London | 26-ITP-Sept | Hugh Mills | Sprint 1 | Sprint 1 Exercises

Sprint-1/fix/median.js

@@ -5,10 +5,31 @@
 // Hint: Please consider scenarios when 'list' isn't an array, is empty,
 // 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];
+//   return median;
+// }
+
+// module.exports = calculateMedian;
+
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMedian requires an array of numbers");
+  } else if (list.some((item) => typeof item !== "number")) {
+    throw new Error("calculateMedian requires an array of numbers");
+  } else if (list.length === 0) {
+    throw new Error("calculateMedian requires a non-empty array");
+  }
+  const copyList = Array.from(list);
+  let sortList = copyList.sort((a, b) => a - b);
+  if (sortList.length % 2 === 1) {
+    const middleIndex = Math.floor(sortList.length / 2);
+    return sortList[middleIndex];
+  }
+  const rightMiddleIndex = Math.floor(sortList.length / 2 - 1);
+  const leftMiddleIndex = Math.floor(sortList.length / 2);
+  return (sortList[rightMiddleIndex] + sortList[leftMiddleIndex]) / 2;
 }
 
 module.exports = calculateMedian;

Sprint-1/implement/dedupe.js

@@ -1 +1,5 @@
-function dedupe() {}
+function dedupe(array) {
+  return [...new Set(array)];
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -1,28 +1,58 @@
 const dedupe = require("./dedupe.js");
 /*
 Dedupe Array
-
 📖 Dedupe means **deduplicate**
-
+*/
+describe("deduplicate", () => {
+  /*
 In this kata, you will need to deduplicate the elements of an array
 
 E.g. dedupe(['a','a','a','b','b','c']) returns ['a','b','c']
 E.g. dedupe([5, 1, 1, 2, 3, 2, 5, 8]) returns [5, 1, 2, 3, 8]
 E.g. dedupe([1, 2, 1]) returns [1, 2]
 */
 
-// Acceptance Criteria:
-
-// 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");
+  // Acceptance Criteria:
 
+  // Given an empty array
+  // When passed to the dedupe function
+  // Then it should return an empty array
+  it(`returns the empty array when given 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
+it("doesn't modify the input array [3, 1, 1, 2]", () => {
+  const array = [3, 1, 1, 2];
+  dedupe(array);
+  expect(array).toEqual([3, 1, 1, 2]);
+});
 
 // 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.
+it(`returns the deduplicate for string letters`, () => {
+  expect(dedupe(["a", "a", "a", "b", "b", "c"])).toEqual(["a", "b", "c"]);
+});
+
+it(`returns the deduplicate for numbers`, () => {
+  expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+});
+
+it(`returns the deduplicate while not numerical in order`, () => {
+  expect(dedupe([1, 2, 1])).toEqual([1, 2]);
+});
+
+it(`returns the deduplicate for string and numbers `, () => {
+  expect(dedupe([5, 1, 1, 2, 3, "a", "a", "a", "c"])).toEqual([
+    5,
+    1,
+    2,
+    3,
+    "a",
+    "c",
+  ]);
+});

Sprint-1/implement/describe-median.js

@@ -20,6 +20,12 @@ function calculateMedian(list) {
 }
 
 // Implement this function. See describe-median.test.js for the acceptance criteria.
-function describeMedian(list) {}
+function describeMedian(list) {
+  try {
+    return `The median is ${calculateMedian(list)}`;
+  } catch (error) {
+    return `Could not calculate a median: ${error.message}`;
+  }
+}
 
 module.exports = describeMedian;

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

@@ -21,12 +21,24 @@ 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"');
+it("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"
+it("returns error 'Could not calculate a median: calculateMedian requires a non-empty array' when array empty", () => {
+  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"
+it("Throws error 'calculateMedian requires an array of numbers' when it isn't 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 +1,19 @@
 function findMax(elements) {
+  if (elements.length === 0) {
+    return "Infinity";
+  }
+  if (!Array.isArray(elements)) {
+    throw new Error("findMax requires an array of numbers");
+  }
+
+  const copyElements = Array.from(elements);
+  for (const item of copyElements) {
+    if (typeof item !== "number") {
+      throw new Error("findMax requires an array of numbers");
+    }
+  }
+  let sortElements = copyElements.sort((a, b) => a - b);
+  return sortElements.at(-1);
 }
 
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -16,28 +16,52 @@ 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");
+it("returns the Infinity for []", () => {
+  expect(findMax([])).toEqual("Infinity");
+});
 
 // Given an array with one number
 // When passed to the max function
 // Then it should return that number
+it("returns the median for [40]", () => {
+  expect(findMax([40])).toEqual(40);
+});
 
 // Given an array with both positive and negative numbers
 // When passed to the max function
 // Then it should return the largest number overall
+it("returns the median for [20, 30, 10, 40]", () => {
+  expect(findMax([20, 30, 10, 40])).toEqual(40);
+});
 
 // Given an array with just negative numbers
 // When passed to the max function
 // Then it should return the closest one to zero
+it("returns the median for [-40, -20, -30, -70]", () => {
+  expect(findMax([-40, -20, -30, -70])).toEqual(-20);
+});
 
 // Given an array with decimal numbers
 // When passed to the max function
 // Then it should return the largest decimal number
+it("returns the median for [-40.4, -20.7, -30.3, -70.6]", () => {
+  expect(findMax([-40.4, -20.7, -30.3, -70.6])).toEqual(-20.7);
+});
 
 // 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")
+it("Throws error 'findMax requires an array of numbers' when containing a value that isn't a number", () => {
+  expect(() => findMax([10, 40, "hello", 30])).toThrow(
+    new Error("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")
+it("Throws error 'findMax requires an array of numbers' Given something that isn't an array at all", () => {
+  expect(() => findMax(42)).toThrow(
+    new Error("findMax requires an array of numbers")
+  );
+});

Sprint-1/implement/mean.js

@@ -1,3 +1,18 @@
-function calculateMean(list) {}
+function calculateMean(list) {
+  if (list.length === 0) {
+    throw new Error("calculateMean requires a non-empty array");
+  }
+
+  if (!Array.isArray(list)) {
+    throw new Error("calculateMean requires an array of numbers");
+  }
+
+  const copyList = Array.from(list);
+  let total = 0;
+  for (let i = 0; i < copyList.length; i++) {
+    total += copyList[i];
+  }
+  return total / copyList.length;
+}
 
 module.exports = calculateMean;

Sprint-1/implement/mean.test.js

@@ -23,28 +23,62 @@ 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");
+it("Returns correct value of 3 for mean of numbers in array of [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 mean of single number in array", () => {
+  expect(calculateMean([6])).toEqual(6);
+});
 
 // Given an array containing negative or decimal numbers
 // When passed to calculateMean
 // Then it should return the correct mean
+it("returns mean containing negative or decimal numbers in array", () => {
+  expect(calculateMean([-6, 8.5, 23])).toEqual(8.5);
+});
 
 // Given an empty array
 // When passed to calculateMean
 // Then it should throw Error("calculateMean requires a non-empty array")
+it("Throws error 'calculateMean requires a non-empty array' Given empty", () => {
+  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 error 'calculateMean requires an array of numbers' Given value that isn't an array", () => {
+  expect(() =>
+    calculateMean("Hello bob").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 error 'calculateMean requires an array of numbers' Given Given no argument at all", () => {
+  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 error 'calculateMean requires an array of numbers' an array containing a non-number value, e.g. [1, '2', 3]", () => {
+  expect(() =>
+    calculateMean([1, "2", 3]).toThrow(
+      new Error("calculateMean requires an array of numbers")
+    )
+  );
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,26 @@
 function sum(elements) {
+  if (elements.length === 0) {
+    return 0;
+  }
+  if (!Array.isArray(elements)) {
+    throw new Error("sum requires an array of numbers");
+  }
+  for (const item of elements) {
+    if (typeof item !== "number") {
+      throw new Error("sum requires an array of numbers");
+    }
+
+    const copyElements = Array.from(elements);
+    let total = 0;
+    for (let i = 0; i < copyElements.length; i++) {
+      total += copyElements[i];
+    }
+    if (Number.isInteger(total)) {
+      return total;
+    } else {
+      return Number(total.toFixed(2));
+    }
+  }
 }
 
 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")
+it("returns 0 when given an empty array", () => {
+  expect(sum([])).toEqual(0);
+});
 
 // Given an array with just one number
 // When passed to the sum function
 // Then it should return that number
+it("returns same number when given an array with just one number", () => {
+  expect(sum([5])).toEqual(5);
+});
 
 // Given an array containing negative numbers
 // When passed to the sum function
 // Then it should still return the correct total sum
+it("returns total when given an array with negative numbers", () => {
+  expect(sum([-5, -2, -10])).toEqual(-17);
+});
 
 // Given an array with decimal/float numbers
 // When passed to the sum function
 // Then it should return the correct total sum
+it("returns total when given an array with decimal/float numbers", () => {
+  expect(sum([2.6, 4.6, 8.12])).toEqual(15.32);
+});
 
 // 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")
+it("throws an error 'sum requires an array of numbers' when value isn't a number", () => {
+  expect(()=> sum(["hello", "bob"])).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")
+it("throws an error 'sum requires an array of numbers' when value isn't an array", () => {
+  expect(() => sum(["2", 2, 5, "bob"])).toThrow(
+    new Error("sum requires an array of numbers")
+  );
+});