Jest-ify tests (#85)

There are also several modifications to tests here:
* mandatory/1-fix-functions.js no longer has `sortArray` or `first5`
  exercises - we moved array methods to week 3, so the tests should move
  there too.
* mandatory/2-function-creation.js has some array-based tests changed to
  instead test the same function creation but for single values. We
  moved teaching `map` to week 3, I'll re-add the array versions of
  these tests to week 3.
* extra/1-radio-stations.js changes how we populate the expected
  stations list, because the tests were previously failing if duplicate
  stations were generated by the random generator.

Author: illicitonion

.gitignore

@@ -0,0 +1,2 @@
+/node_modules/
+/package-lock.json

extra/1-radio-stations.js

@@ -26,21 +26,26 @@
  */
 // `getStations` goes here
 
-/* ======= TESTS - DO NOT MODIFY ======= */
+/*
+ * ======= TESTS - DO NOT MODIFY =======
+ * Note: You are not expected to understand everything below this comment!
+ */
 
 function getAvailableStations() {
   // Using `stations` as a property as defining it as a global variable wouldn't
   // always make it initialized before the function is called
   if (!getAvailableStations.stations) {
     const stationCount = 4;
-    getAvailableStations.stations = new Array(stationCount)
-      .fill(undefined)
-      .map(function () {
-        return Math.floor(Math.random() * (108 - 87 + 1) + 87);
-      })
-      .sort(function (frequencyA, frequencyB) {
-        return frequencyA - frequencyB;
-      });
+    getAvailableStations.stations = [];
+    while (getAvailableStations.stations.length < stationCount) {
+      let randomFrequency = Math.floor(Math.random() * (108 - 87 + 1) + 87);
+      if (!getAvailableStations.stations.includes(randomFrequency)) {
+        getAvailableStations.stations.push(randomFrequency);
+      }
+    }
+    getAvailableStations.stations.sort(function (frequencyA, frequencyB) {
+      return frequencyA - frequencyB;
+    });
   }
 
   return getAvailableStations.stations;
@@ -50,48 +55,13 @@ function isRadioStation(frequency) {
   return getAvailableStations().includes(frequency);
 }
 
-const assert = require("assert");
-
-function test(testName, fn) {
-  try {
-    fn();
-    console.log(`\n✅ ${testName}: PASS`);
-  } catch (error) {
-    console.log(
-      `\n❌ ${testName}: FAIL (see details below)\n\n${error.message}`
-    );
-  }
-}
-
-test("getAllFrequencies() returns all frequencies between 87 and 108", function () {
-  const frequencies = getAllFrequencies();
-  assert.deepStrictEqual(frequencies, [
-    87,
-    88,
-    89,
-    90,
-    91,
-    92,
-    93,
-    94,
-    95,
-    96,
-    97,
-    98,
-    99,
-    100,
-    101,
-    102,
-    103,
-    104,
-    105,
-    106,
-    107,
-    108,
+test("getAllFrequencies() returns all frequencies between 87 and 108", () => {
+  expect(getAllFrequencies()).toEqual([
+    87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104,
+    105, 106, 107, 108,
   ]);
 });
 
 test("getStations() returns all the available stations", () => {
-  const stations = getStations();
-  assert.deepStrictEqual(stations, getAvailableStations());
+  expect(getStations()).toEqual(getAvailableStations());
 });

mandatory/1-fix-functions.js

@@ -30,18 +30,6 @@ function greaterThan10(num) {
   }
 }
 
-function sortArray(letters) {
-  let sortedLetters = letters;
-
-  return sortedLetters;
-}
-
-function first5(numbers) {
-  let sliced;
-
-  return sliced;
-}
-
 function get3rdIndex(arr) {
   let index = 3;
   let element;
@@ -51,80 +39,47 @@ function get3rdIndex(arr) {
 
 /* ======= TESTS - DO NOT MODIFY ===== */
 
-const util = require("util");
-
-function test(test_name, actual, expected) {
-  let status;
-
-  let isEqual;
-  if (Array.isArray(expected)) {
-    isEqual = arraysEqual(actual, expected);
-  } else {
-    isEqual = actual === expected;
-  }
-
-  if (isEqual) {
-    status = "PASSED";
-  } else {
-    status = `FAILED: expected: ${util.inspect(
-      expected
-    )} but your function returned: ${util.inspect(actual)}`;
-  }
-
-  console.log(`${test_name}: ${status}`);
-}
-
-function arraysEqual(a, b) {
-  if (a === b) return true;
-  if (a == null || b == null) return false;
-  if (a.length != b.length) return false;
-
-  for (let i = 0; i < a.length; ++i) {
-    if (a[i] !== b[i]) return false;
-  }
-
-  return true;
-}
-
-test("mood function works for true", mood(true), "I am happy");
-test("mood function works for false", mood(false), "I am not happy");
-test(
-  "greaterThanTen function works for 11",
-  greaterThan10(11),
-  "num is greater than 10"
-);
-test(
-  "greaterThanTen function works for 10",
-  greaterThan10(10),
-  "num is not big enough"
-);
-test(
-  "greaterThanTen function works for 9",
-  greaterThan10(9),
-  "num is not big enough"
-);
-test("sortArray function works", sortArray(["a", "n", "c", "e", "z", "f"]), [
-  "a",
-  "c",
-  "e",
-  "f",
-  "n",
-  "z",
-]);
-
-let numbers = [1, 2, 3, 4, 5, 6, 7, 8];
-test("first5 function works", first5(numbers), [1, 2, 3, 4, 5]);
-if (!arraysEqual(numbers, [1, 2, 3, 4, 5, 6, 7, 8])) {
-  console.log("PROBLEM: first5 changed its input array - it shouldn't!");
-}
-
-test(
-  "get3rdIndex function works - case 1",
-  get3rdIndex(["fruit", "banana", "apple", "strawberry", "raspberry"]),
-  "strawberry"
-);
-test(
-  "get3rdIndex function works - case 2",
-  get3rdIndex([11, 37, 62, 18, 19, 3, 30]),
-  18
-);
+test("mood function works for true", () => {
+  expect(mood(true)).toEqual("I am happy");
+});
+
+test("mood function works for false", () => {
+  expect(mood(false)).toEqual("I am not happy");
+});
+
+test("greaterThanTen function works for value greater than 10", () => {
+  expect(greaterThan10(11)).toEqual("num is greater than 10");
+});
+
+test("greaterThanTen function works for value much greater than 10", () => {
+  expect(greaterThan10(96)).toEqual("num is greater than 10");
+});
+
+test("greaterThanTen function works for value less than 10", () => {
+  expect(greaterThan10(9)).toEqual("num is not big enough");
+});
+
+test("greaterThanTen function works for value equal to 10", () => {
+  expect(greaterThan10(10)).toEqual("num is not big enough");
+});
+
+test("get3rdIndex function works with strings", () => {
+  const strings = ["fruit", "banana", "apple", "strawberry", "raspberry"];
+  const copyOfOriginal = strings.slice();
+  expect(get3rdIndex(strings)).toEqual("strawberry");
+  // Make sure get3rdIndex didn't change its input array.
+  expect(strings).toEqual(copyOfOriginal);
+});
+
+test("get3rdIndex function works with numbers", () => {
+  const numbers = [11, 37, 62, 18, 19, 3, 30];
+  const copyOfOriginal = numbers.slice();
+  expect(get3rdIndex(numbers)).toEqual(18);
+  // Make sure get3rdIndex didn't change its input array.
+  expect(numbers).toEqual(copyOfOriginal);
+});
+
+test("get3rdIndex returns undefined if not enough elements", () => {
+  const numbers = [5, 10];
+  expect(get3rdIndex(numbers)).toBeUndefined();
+});