Manchester | 26-ITP-May | Samreen Amjad | Sprint 1 | Exercises

Sprint-1/fix/median.js

@@ -6,9 +6,24 @@
 // or 'list' has mixed values (the function is expected to sort only numbers).
 
 function calculateMedian(list) {
-  const middleIndex = Math.floor(list.length / 2);
-  const median = list.splice(middleIndex, 1)[0];
-  return median;
+  if (!Array.isArray(list)) {
+    return null;
+  }
+  let numberArray = list.filter((n) => Number.isFinite(n));
+  if (numberArray.length == 0) {
+    return null;
+  }
+  numberArray.sort((a, b) => a - b);
+
+  if (numberArray.length % 2 == 1) {
+    return numberArray[(numberArray.length - 1) / 2];
+  } else {
+    return (
+      (numberArray[numberArray.length / 2] +
+        numberArray[numberArray.length / 2 - 1]) /
+      2
+    );
+  }
 }
 
 module.exports = calculateMedian;

Sprint-1/fix/median.test.js

@@ -13,8 +13,9 @@ describe("calculateMedian", () => {
     { input: [1, 2, 3, 4], expected: 2.5 },
     { input: [1, 2, 3, 4, 5, 6], expected: 3.5 },
   ].forEach(({ input, expected }) =>
-    it(`returns the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
-  );
+     it(`returns the median for [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
+   );
 
   [
     { input: [3, 1, 2], expected: 2 },
@@ -24,7 +25,8 @@ describe("calculateMedian", () => {
     { input: [110, 20, 0], expected: 20 },
     { input: [6, -2, 2, 12, 14], expected: 6 },
   ].forEach(({ input, expected }) =>
-    it(`returns the correct median for unsorted array [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`returns the correct median for unsorted array [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 
   it("doesn't modify the input array [3, 1, 2]", () => {
@@ -33,8 +35,17 @@ describe("calculateMedian", () => {
     expect(list).toEqual([3, 1, 2]);
   });
 
-  [ 'not an array', 123, null, undefined, {}, [], ["apple", null, undefined] ].forEach(val =>
-    it(`returns null for non-numeric array (${val})`, () => expect(calculateMedian(val)).toBe(null))
+  [
+    "not an array",
+    123,
+    null,
+    undefined,
+    {},
+    [],
+    ["apple", null, undefined],
+  ].forEach((val) =>
+    it(`returns null for non-numeric array (${val})`, () =>
+      expect(calculateMedian(val)).toBe(null))
   );
 
   [
@@ -45,6 +56,7 @@ describe("calculateMedian", () => {
     { input: [3, "apple", 1, null, 2, undefined, 4], expected: 2.5 },
     { input: ["banana", 5, 3, "apple", 1, 4, 2], expected: 3 },
   ].forEach(({ input, expected }) =>
-    it(`filters out non-numeric values and calculates the median for [${input}]`, () => expect(calculateMedian(input)).toEqual(expected))
+    it(`filters out non-numeric values and calculates the median for [${input}]`, () =>
+      expect(calculateMedian(input)).toEqual(expected))
   );
 });

Sprint-1/implement/dedupe.js

@@ -1 +1,11 @@
-function dedupe() {}
+function dedupe(array) {
+  const unique = [];
+  array.forEach((item) => {
+    if (!unique.includes(item)) {
+      unique.push(item);
+    }
+  });
+  return unique;
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -16,13 +16,40 @@ 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");
-
+describe("dedupe", () => {
+  [{ input: [], expected: [] }].forEach(({ input, expected }) =>
+    it(`returns empty array for [${input}]`, () =>
+      expect(dedupe(input)).toEqual(expected))
+  );
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
-
+ [
+    { input: [1, 2, 3], expected: [1, 2, 3] },
+    { input: [3, 2, 1, 4, 5], expected: [3, 2, 1, 4, 5] },
+    { input: ["hello", "a", "b", "c"], expected: ["hello", "a", "b", "c"] },
+    { input: [1, 2, "hello", 4, "a", 6], expected: [1, 2, "hello", 4, "a", 6] },
+  ].forEach(({ input, expected }) => {
+    it(`returns array with same contents for [${input}]`, () =>
+      expect(dedupe(input)).toEqual(expected));
+    it(`returns a non-identical array (copy) for [${input}]`, () =>
+      expect(dedupe(input)).not.toBe(input));
+  });
 // Given an array of strings or numbers
 // When passed to the dedupe function
 // Then it should return a new array with duplicates removed while preserving the 
 // first occurrence of each element from the original array.
+[
+    { input: [1, 1, 2, 2, 3, 3], expected: [1, 2, 3] },
+    { input: ["a", "a", "b", "b", "c", "c"], expected: ["a", "b", "c"] },
+    {
+      input: ["qwe", "qwe", 3, 3, "hello", "hello", "hello"],
+      expected: ["qwe", 3, "hello"],
+    },
+    { input: ["a", "a", "a", "a"], expected: ["a"] },
+    { input: [1, 2, 2, 2, 2, 2], expected: [1, 2] },
+  ].forEach(({ input, expected }) =>
+    it(`returns no duplicates for [${input}]`, () =>
+      expect(dedupe(input)).toEqual(expected))
+  );
+});

Sprint-1/implement/max.js

@@ -1,4 +1,9 @@
-function findMax(elements) {
+function findMax(list) {
+  const numbers = list.filter((n) => Number.isFinite(n));
+  if (numbers.length == 0) {
+    return -Infinity;
+  } else {
+    return Math.max(...numbers);
+  }
 }
-
 module.exports = findMax;

Sprint-1/implement/max.test.js

@@ -12,32 +12,68 @@ We have set things up already so that this file can see your function from the o
 
 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");
-
-// Given an array with one number
-// When passed to the max function
-// Then it should return that number
-
-// Given an array with both positive and negative numbers
-// When passed to the max function
-// Then it should return the largest number overall
-
-// Given an array with just negative numbers
-// When passed to the max function
-// Then it should return the closest one to zero
-
-// Given an array with decimal numbers
-// When passed to the max function
-// Then it should return the largest decimal number
-
-// Given an array with non-number values
-// When passed to the max function
-// Then it should return the max and ignore non-numeric values
-
-// Given an array with only non-number values
-// When passed to the max function
-// Then it should return the least surprising value given how it behaves for all other inputs
+describe("calculateMedian", () => {
+  // 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.
+
+  it("empty array returns -Infinity", () => {
+    const list = [];
+    expect(findMax(list)).toEqual(-Infinity);
+  });
+
+  // Given an array with one number
+  // When passed to the max function
+  // Then it should return that number
+
+  it("array with one number returns that number", () => {
+    const list = [2];
+    expect(findMax(list)).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
+
+  it("array with +ve and -ve numbers, returns largest number overall", () => {
+    const list = [10, -15];
+    expect(findMax(list)).toEqual(10);
+  });
+
+  // Given an array with just negative numbers
+  // When passed to the max function
+  // Then it should return the closest one to zero
+
+  it("array -ve numbers, returns closest to zero", () => {
+    const list = [-1, -2, -3, -15];
+    expect(findMax(list)).toEqual(-1);
+  });
+
+  // Given an array with decimal numbers
+  // When passed to the max function
+  // Then it should return the largest decimal number
+
+  it("array with decimal numbers should return largest decimal number", () => {
+    const list = [1.9, 2.8999, 3.1];
+    expect(findMax(list)).toEqual(3.1);
+  });
+
+  // Given an array with non-number values
+  // When passed to the max function
+  // Then it should return the max and ignore non-numeric values
+
+  it("array with non-number values, returns the max and ignore non-numeric values", () => {
+    const list = [1, "a", 2, "b", 3, "c"];
+    expect(findMax(list)).toEqual(3);
+  });
+
+  // Given an array with only non-number values
+  // When passed to the max function
+  // Then it should return the least surprising value given how it behaves for all other inputs
+
+  it("array with only non-number values, return the least surprising value given how it behaves for all other inputs", () => {
+    const list = ["a", "b", "c"];
+    expect(findMax(list)).toEqual(-Infinity);
+  });
+});

Sprint-1/implement/sum.js

@@ -1,4 +1,10 @@
-function sum(elements) {
+function sum(list) {
+  const numbers = list.filter((n) => Number.isFinite(n));
+  let total = 0;
+  for (n of numbers) {
+    total += n;
+  }
+  return total;
 }
 
 module.exports = sum;

Sprint-1/implement/sum.test.js

@@ -10,27 +10,56 @@ const sum = require("./sum.js");
 
 // Acceptance Criteria:
 
-// Given an empty array
-// When passed to the sum function
-// Then it should return 0
-test.todo("given an empty array, returns 0")
-
-// Given an array with just one number
-// When passed to the sum function
-// Then it should return that number
-
-// Given an array containing negative numbers
-// When passed to the sum function
-// Then it should still return the correct total sum
-
-// Given an array with decimal/float numbers
-// When passed to the sum function
-// Then it should return the correct total sum
-
-// Given an array containing non-number values
-// When passed to the sum function
-// Then it should ignore the non-numerical values and return the sum of the numerical elements
-
-// Given an array with only non-number values
-// When passed to the sum function
-// Then it should return the least surprising value given how it behaves for all other inputs
+describe("sum", () => {
+  // Given an empty array
+  // When passed to the sum function
+  // Then it should return 0
+  it("empty array returns 0", () => {
+    const list = [];
+    expect(sum(list)).toEqual(0);
+  });
+
+  // Given an array with just one number
+  // When passed to the sum function
+  // Then it should return that number
+  it("array with one number returns number", () => {
+    const list = [1];
+    expect(sum(list)).toEqual(1);
+  });
+
+  // Given an array containing negative numbers
+  // When passed to the sum function
+  // Then it should still return the correct total sum
+
+  it("array with negative numbers returns correct sum", () => {
+    const list = [-1, -2, -3];
+    expect(sum(list)).toEqual(-6);
+  });
+
+  // Given an array with decimal/float numbers
+  // When passed to the sum function
+  // Then it should return the correct total sum
+
+  it("array with decimal numbers returns correct sum", () => {
+    const list = [1.1, 2.2, 3.3];
+    expect(sum(list)).toEqual(6.6);
+  });
+
+  // Given an array containing non-number values
+  // When passed to the sum function
+  // Then it should ignore the non-numerical values and return the sum of the numerical elements
+
+  it("array with non-number values returns sum of numerical values only", () => {
+    const list = [1, 2, "apple", 4, "banana", 3];
+    expect(sum(list)).toEqual(10);
+  });
+
+  // Given an array with only non-number values
+  // When passed to the sum function
+  // Then it should return the least surprising value given how it behaves for all other inputs
+
+  it("array with non-number values only returns least surprising output", () => {
+    const list = ["a", "b", "c"];
+    expect(sum(list)).toEqual(0);
+  });
+});