-
Notifications
You must be signed in to change notification settings - Fork 0
/
round-linked-queue.test.js
118 lines (90 loc) · 3.79 KB
/
round-linked-queue.test.js
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
const chai = require("chai");
const expect = chai.expect;
const RoundQueue = require("./round-linked-queue");
describe("Round-Queue", () => {
describe("When creating an instance", () => {
it("Should properly set the maxLength property", () => {
const queueLength = 3;
const queue = new RoundQueue(queueLength);
expect(queue.maxLength).to.equal(queueLength);
});
it("Should initially set the length to zero", () => {
const queueLength = 3;
const queue = new RoundQueue(queueLength);
expect(queue.length).to.equal(0);
});
});
describe("When adding elements", () => {
it("Should add an element to an empty queue", () => {
const queue = new RoundQueue(3);
const originalLength = queue.length;
const elementToAdd = 1;
queue.add(elementToAdd);
// Element should've been added to the end of the queue
expect(queue.last).to.equal(elementToAdd);
// But since it is now the only element, it should also be the at beginning as well
expect(queue.first).to.equal(elementToAdd);
// Length should've been increased by 1
expect(queue.length).to.equal(originalLength + 1);
});
it("Should add an element to the end of a non-empty queue", () => {
const queue = new RoundQueue(3);
const previousElement = 1;
const elementToAdd = 2;
// Make the queue non-empty
queue.add(previousElement);
queue.add(elementToAdd);
// Element should've been added to the end of the queue
expect(queue.last).to.equal(elementToAdd, "last not properly set");
// But the first pointer must remain the first element added
expect(queue.first).to.equal(previousElement, "first not properly set");
// Length should've been increased by 2
expect(queue.length).to.equal(2, "length not properly set");
});
it("Should remove the first element and add the new element to the end of a full queue", () => {
const queue = new RoundQueue(3);
queue.add(1);
queue.add(2);
queue.add(3);
queue.add(4);
// Element should've been added to the end of the queue
expect(queue.last).to.equal(4, "last not properly set");
// The second element should've been shifted to the first position
expect(queue.first).to.equal(2, "first not properly set");
// Length should still be the same
expect(queue.length).to.equal(3, "length not properly set");
});
it("Should return the removed element from a full queue", () => {
const queue = new RoundQueue(3);
queue.add(1);
queue.add(2);
queue.add(3);
const result = queue.add(4);
expect(result).to.equal(1, "removed wrong element");
});
it("Should return undefined when the queue is not full", () => {
const queue = new RoundQueue(3);
const result = queue.add(1);
expect(result).to.equal(undefined, "should not return an element");
});
});
describe("When removing elements", () => {
it("Should remove the first element of a non-empty queue", () => {
const queue = new RoundQueue(3);
queue.add(1);
queue.add(2);
queue.add(3);
const lengthBefore = queue.length;
const result = queue.remove();
const lengthAfter = queue.length;
expect(lengthAfter).to.equal(lengthBefore - 1, "length should decrease by 1");
expect(result).to.equal(1, "first element should the one being removed");
expect(queue.first).to.equal(2, "should shift the second element to the head of the queue");
expect(queue.last).to.equal(3, "should not change the last element");
});
it("Should throw an error when the queue is empty", () => {
const queue = new RoundQueue(3);
expect(() => queue.remove()).to.throw("Cannot remove element from an empty queue");
});
});
});