Initialize unit testing and code coverage

* add: vitest configs

* added vitest scripts to package

* test coverage of src code

* initial unit testing

* added new testing workflows

* comments added, overlapping tests removed

* decouple env, tests

---------

Co-authored-by: Kevin Dang <kevinthedang_1@outlook.com>

tests/queue.test.ts

@@ -0,0 +1,62 @@
+import { describe, expect, it } from 'vitest'
+import { Queue } from '../src/queues/queue'
+
+/**
+ * Queue test suite, tests the Queue class
+ * 
+ * @param name name of the test suite
+ * @param fn function holding tests to run
+ */
+describe('#queue', () => {
+    let queue= new Queue<string>()
+
+    // test for queue creation
+    it('creates a new queue', () => {
+        expect(queue).not.toBeNull()
+    })
+
+    // test for queue capacity creation
+    it('adds specific capacity to the queue', () => {
+        queue = new Queue<string>(2)
+        expect(queue).not.toBeNull()
+    })
+
+    // test for enqueue success, size update
+    it('adds items to the queue', () => {
+        queue.enqueue('hello')
+        expect(queue.size()).toBe(1)
+    })
+
+    // test for multiple enqueue success, size update
+    it('adds multiple items to the queue', () => {
+        queue.enqueue('world')
+        expect(queue.size()).toBe(2)
+    })
+
+    // test for enqueue failure upon capacity overflow
+    it('throws an error when the queue is full', () => {
+        expect(() => queue.enqueue('!')).toThrowError()
+    })
+
+    // test for getItems success
+    it('returns all items in the queue', () => {
+        expect(queue.getItems()).toEqual(['hello', 'world'])
+    })
+
+    // test for pop success, size update
+    it('removes an item from the front of the queue', () => {
+        queue.pop()
+        expect(queue.size() && queue.getItems()[0]).toBe(1 && 'hello')
+    })
+
+    // test for dequeue success, size update
+    it('removes an item from the back of the queue', () => {
+        queue.dequeue()
+        expect(queue.size() && queue.getItems()[0]).toBe(0 && 'world')
+    })
+
+    // test for getItems success with nothing in the list
+    it('returns an empty array when the queue is empty', () => {
+        expect(queue.getItems()).toEqual([])
+    })
+})