From d42f95e71cb2132f38debee327788bcc487ec8d7 Mon Sep 17 00:00:00 2001
From: Zack Schuster <email@zackschuster.com>
Date: Wed, 27 May 2020 05:31:36 -0700
Subject: [PATCH] smtp/error: convert makeSMTPError to static method of
 exported SMTPError class

---
 smtp/error.ts    | 46 +++++++++++++++++++++++++++++-----------------
 smtp/response.ts | 10 +++++-----
 smtp/smtp.ts     | 16 ++++++++--------
 3 files changed, 42 insertions(+), 30 deletions(-)

diff --git a/smtp/error.ts b/smtp/error.ts
index a56c414..ad7ee45 100644
--- a/smtp/error.ts
+++ b/smtp/error.ts
@@ -15,31 +15,43 @@ export const SMTPErrorStates = {
 	CONNECTIONAUTH: 10,
 } as const;
 
-class SMTPError extends Error {
+export class SMTPError extends Error {
 	public code: number | null = null;
 	public smtp: unknown = null;
 	public previous: Error | null = null;
 
-	constructor(message: string) {
+	/**
+	 * @protected
+	 * @param {string} message error message
+	 */
+	protected constructor(message: string) {
 		super(message);
 	}
-}
 
-export function makeSMTPError(
-	message: string,
-	code: number,
-	error?: Error | null,
-	smtp?: unknown
-) {
-	const msg = error?.message ? `${message} (${error.message})` : message;
-	const err = new SMTPError(msg);
+	/**
+	 *
+	 * @param {string} message error message
+	 * @param {number} code smtp error state
+	 * @param {Error | null} error previous error
+	 * @param {unknown} smtp arbitrary data
+	 * @returns {SMTPError} error
+	 */
+	public static create(
+		message: string,
+		code: number,
+		error?: Error | null,
+		smtp?: unknown
+	) {
+		const msg = error?.message ? `${message} (${error.message})` : message;
+		const err = new SMTPError(msg);
 
-	err.code = code;
-	err.smtp = smtp;
+		err.code = code;
+		err.smtp = smtp;
 
-	if (error) {
-		err.previous = error;
+		if (error) {
+			err.previous = error;
+		}
+
+		return err;
 	}
-
-	return err;
 }
diff --git a/smtp/response.ts b/smtp/response.ts
index 9bd229c..4f4539c 100644
--- a/smtp/response.ts
+++ b/smtp/response.ts
@@ -1,4 +1,4 @@
-import { makeSMTPError, SMTPErrorStates } from './error';
+import { SMTPError, SMTPErrorStates } from './error';
 import type { Socket } from 'net';
 import type { TLSSocket } from 'tls';
 
@@ -42,7 +42,7 @@ export class SMTPResponse {
 		const error = (err: Error) => {
 			stream.emit(
 				'response',
-				makeSMTPError(
+				SMTPError.create(
 					'connection encountered an error',
 					SMTPErrorStates.ERROR,
 					err
@@ -54,7 +54,7 @@ export class SMTPResponse {
 			stream.end();
 			stream.emit(
 				'response',
-				makeSMTPError(
+				SMTPError.create(
 					'timedout while connecting to smtp server',
 					SMTPErrorStates.TIMEDOUT,
 					err
@@ -72,7 +72,7 @@ export class SMTPResponse {
 		const close = (err: Error) => {
 			stream.emit(
 				'response',
-				makeSMTPError(
+				SMTPError.create(
 					'connection has closed',
 					SMTPErrorStates.CONNECTIONCLOSED,
 					err
@@ -83,7 +83,7 @@ export class SMTPResponse {
 		const end = (err: Error) => {
 			stream.emit(
 				'response',
-				makeSMTPError(
+				SMTPError.create(
 					'connection has ended',
 					SMTPErrorStates.CONNECTIONENDED,
 					err
diff --git a/smtp/smtp.ts b/smtp/smtp.ts
index ab1f3dd..6fafd40 100644
--- a/smtp/smtp.ts
+++ b/smtp/smtp.ts
@@ -4,8 +4,8 @@ import { hostname } from 'os';
 import { connect, createSecureContext, TLSSocket } from 'tls';
 import { EventEmitter } from 'events';
 
+import { SMTPError, SMTPErrorStates } from './error';
 import { SMTPResponse } from './response';
-import { makeSMTPError, SMTPErrorStates } from './error';
 
 /**
  * @readonly
@@ -251,7 +251,7 @@ export class SMTPConnection extends EventEmitter {
 					this.close(true);
 					caller(
 						callback,
-						makeSMTPError(
+						SMTPError.create(
 							'could not establish an ssl connection',
 							SMTPErrorStates.CONNECTIONAUTH
 						)
@@ -274,7 +274,7 @@ export class SMTPConnection extends EventEmitter {
 				this.log(err);
 				caller(
 					callback,
-					makeSMTPError(
+					SMTPError.create(
 						'could not connect',
 						SMTPErrorStates.COULDNOTCONNECT,
 						err
@@ -304,7 +304,7 @@ export class SMTPConnection extends EventEmitter {
 				this.quit(() => {
 					caller(
 						callback,
-						makeSMTPError(
+						SMTPError.create(
 							'bad response on connection',
 							SMTPErrorStates.BADRESPONSE,
 							err,
@@ -360,7 +360,7 @@ export class SMTPConnection extends EventEmitter {
 			this.close(true);
 			caller(
 				callback,
-				makeSMTPError(
+				SMTPError.create(
 					'no connection has been established',
 					SMTPErrorStates.NOCONNECTION
 				)
@@ -402,7 +402,7 @@ export class SMTPConnection extends EventEmitter {
 					}'${suffix}`;
 					caller(
 						callback,
-						makeSMTPError(
+						SMTPError.create(
 							errorMessage,
 							SMTPErrorStates.BADRESPONSE,
 							null,
@@ -763,7 +763,7 @@ export class SMTPConnection extends EventEmitter {
 				this.close(); // if auth is bad, close the connection, it won't get better by itself
 				caller(
 					callback,
-					makeSMTPError(
+					SMTPError.create(
 						'authorization.failed',
 						SMTPErrorStates.AUTHFAILED,
 						err,
@@ -855,7 +855,7 @@ export class SMTPConnection extends EventEmitter {
 					break;
 				default:
 					const msg = 'no form of authorization supported';
-					const err = makeSMTPError(
+					const err = SMTPError.create(
 						msg,
 						SMTPErrorStates.AUTHNOTSUPPORTED,
 						null,