Improve code quality and add decrypt status return value

tests/encrypt.test.ts

@@ -1,20 +1,17 @@
+import { decrypt } from '../src/decrypt'
 import { encrypt } from '../src/encrypt'
 
-test('Test buffers are supported by encrypt function.', () => {
+test('Test nonce generation by public encrypt function.', () => {
   // Given
   const message = Buffer.from('Hello, World! This is a test message.')
   const associatedData = Buffer.from('Some associated data.')
-  const nonce = Buffer.from('\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f')
   const key = Buffer.from('\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f')
 
   // When
-  const result = encrypt(message, associatedData, nonce, key)
+  const ciphertext = encrypt(message, associatedData, key)
+  const plaintext = decrypt(ciphertext, associatedData, key)
 
   // Then
-  const expectedResult = Buffer.from([
-    225, 53, 3, 212, 22, 112, 246, 194, 61, 171, 230, 187, 157, 102, 32, 76, 62, 65,
-    25, 202, 255, 201, 206, 49, 60, 58, 82, 216, 72, 116, 106, 129, 162, 142, 69, 40,
-    167, 88, 94, 195, 174, 217, 242, 149, 224, 125, 196, 237, 172, 165, 116, 119, 128
-  ])
-  expect(result).toMatchObject(expectedResult)
+  expect(plaintext.success).toBe(true)
+  expect(plaintext.plaintext).toMatchObject(message)
 })