feat(logger): log internal server errors

src/Config.ts

@@ -0,0 +1,5 @@
+import { Logger } from "./logger";
+
+export class Config {
+    public logger: Logger = console;
+}

src/handler/APIGatewayProxyHandler.ts

@@ -8,7 +8,7 @@ import {
     ValidationError,
     UnauthorizedError,
 } from "../error";
-import { UnprocessableEntityError } from "../error/UnprocessableEntityError";
+import { UnprocessableEntityError } from "../error";
 import { ContentTypeHeader, CORSHeader, Header, Headers } from "../header";
 import {
     badRequest,
@@ -23,6 +23,7 @@ import {
     unprocessableEntity,
 } from "../response";
 import { BaseHandler, BaseHandlerArguments } from "./BaseHandler";
+import { config } from "../index";
 
 export interface APIGatewayProxyHandlerArguments extends BaseHandlerArguments {
     cors?: CORSHeader;
@@ -48,10 +49,15 @@ export class APIGatewayProxyHandler extends BaseHandler {
         if (err instanceof NotFoundError) {
             return notFound(err.details);
         }
+        config.logger.error({
+            name: err.name,
+            message: err.message,
+            stack: err.stack,
+        });
         return internalServerError();
     }
 
-    private corsHeader: Header;
+    private readonly corsHeader: Header;
 
     constructor(args?: APIGatewayProxyHandlerArguments) {
         super(args);

src/handler/BaseHandler.ts

@@ -37,10 +37,13 @@ import {
 import { Format } from "../format/Format";
 import * as inputFormat from "../format/InputFormat";
 import * as outputFormat from "../format/OutputFormat";
+import { Logger } from "../logger";
+import { config } from "../index";
 
 export interface BaseHandlerArguments {
     inputFormat?: Format;
     outputFormat?: Format;
+    logger?: Logger;
 }
 
 type Event =
@@ -84,9 +87,12 @@ export abstract class BaseHandler {
     protected inputFormat: Format;
     protected outputFormat: Format;
 
-    constructor(args?: BaseHandlerArguments) {
+    protected constructor(args?: BaseHandlerArguments) {
         this.inputFormat = args?.inputFormat ?? inputFormat.json;
         this.outputFormat = args?.outputFormat ?? outputFormat.json;
+        if (args?.logger) {
+            config.logger = args.logger;
+        }
     }
 
     public decorator(

src/index.ts

@@ -1,3 +1,5 @@
+import { Config } from "./Config";
+
 export * from "./decorator/format";
 export * from "./decorator/handler";
 export * from "./decorator/header";
@@ -6,6 +8,8 @@ export * from "./error";
 import * as input from "./format/InputFormat";
 import * as output from "./format/OutputFormat";
 
+export const config = new Config();
+
 export const format = {
     input,
     output,

src/logger.ts

@@ -0,0 +1,9 @@
+export type JSONType = { [key: string]: unknown };
+export type LoggerArgument = (JSONType | string | unknown)[];
+
+export interface Logger {
+    info(...args: LoggerArgument): void;
+    warn(...args: LoggerArgument): void;
+    error(...args: LoggerArgument): void;
+    debug(...args: LoggerArgument): void;
+}