Get rid of next! in App.use()

src/App.spec.ts

@@ -14,7 +14,7 @@ import { WebClientOptions, WebClient } from '@slack/web-api';
 // TODO: swap out rewiremock for proxyquire to see if it saves execution time
 // Utility functions
 const noop = (() => Promise.resolve(undefined));
-const noopMiddleware = async ({ next }: { next: NextFn; }) => { await next!(); };
+const noopMiddleware = async ({ next }: { next: NextFn; }) => { await next(); };
 const noopAuthorize = (() => Promise.resolve({}));
 
 // Dummies (values that have no real behavior but pass through the system opaquely)
@@ -347,8 +347,8 @@ describe('App', () => {
  // Arrange
  app.use(fakeFirstMiddleware);
  app.use(async ({ next }) => {
- await next!();
- await next!();
+ await next();
+ await next();
  });
  app.use(fakeSecondMiddleware);
  app.error(fakeErrorHandler);
@@ -367,7 +367,7 @@ describe('App', () => {
  await delay(100);
  changed = true;
 
- await next!();
+ await next();
  });
 
  await fakeReceiver.sendEvent(dummyReceiverEvent);
@@ -381,7 +381,7 @@ describe('App', () => {
 
  app.use(async ({ next }) => {
  try {
- await next!();
+ await next();
  } catch (err) {
  caughtError = err;
  }
@@ -713,7 +713,7 @@ describe('App', () => {
 
  app.use(async ({ next }) => {
  await ackFn();
- await next!();
+ await next();
  });
  app.shortcut({ callback_id: 'message_action_callback_id' }, async ({ }) => { await shortcutFn(); });
  app.shortcut(
@@ -857,7 +857,7 @@ describe('App', () => {
  });
  app.use(async ({ logger, body, next }) => {
  logger.info(body);
- await next!();
+ await next();
  });
 
  app.event('app_home_opened', async ({ logger, event }) => {
@@ -905,7 +905,7 @@ describe('App', () => {
  });
  app.use(async ({ logger, body, next }) => {
  logger.info(body);
- await next!();
+ await next();
  });
 
  app.event('app_home_opened', async ({ logger, event }) => {
@@ -971,7 +971,7 @@ describe('App', () => {
  });
  app.use(async ({ client, next }) => {
  await client.auth.test();
- await next!();
+ await next();
  });
  const clients: WebClient[] = [];
  app.event('app_home_opened', async ({ client }) => {

src/App.ts

@@ -49,6 +49,7 @@ import {
  RespondArguments,
 } from './types';
 import { IncomingEventType, getTypeAndConversation, assertNever } from './helpers';
+import { NonListenerMiddlewareArgs, NonListenerMiddleware } from './types/middleware';
 import {
  CodedError,
  asCodedError,
@@ -275,8 +276,18 @@ export default class App {
  *
  * @param m global middleware function
  */
- public use(m: Middleware<AnyMiddlewareArgs>): this {
- this.middleware.push(m);
+ public use(m: NonListenerMiddleware): this {
+ const middleware: Middleware<AnyMiddlewareArgs> = (args) => {
+ const _args: NonListenerMiddlewareArgs = {
+ context: args.context,
+ logger: args.logger,
+ client: args.client,
+ next: args.next!,
+ ...args,
+ };
+ return m(_args);
+ };
+ this.middleware.push(middleware);
  return this;
  }
 

src/conversation-store.ts

@@ -1,6 +1,7 @@
-import { Middleware, AnyMiddlewareArgs } from './types';
+import { Middleware } from './types';
 import { Logger } from '@slack/logger';
 import { getTypeAndConversation } from './helpers';
+import { NonListenerMiddlewareArgs } from './types/middleware';
 
 /**
  * Storage backend used by the conversation context middleware
@@ -54,7 +55,7 @@ export class MemoryStore<ConversationState = any> implements ConversationStore<C
 export function conversationContext<ConversationState = any>(
  store: ConversationStore<ConversationState>,
  logger: Logger,
-): Middleware<AnyMiddlewareArgs> {
+): Middleware<NonListenerMiddlewareArgs> {
  return async (args) => {
  const { body, context, next } = args;
  const { conversationId } = getTypeAndConversation(body as any);
@@ -74,7 +75,7 @@ export function conversationContext<ConversationState = any>(
  } else {
  logger.debug('No conversation ID for incoming event');
  // TODO: remove the non-null assertion operator
- await next!();
+ await next();
  }
  };
 }

src/middleware/builtin.ts

@@ -23,6 +23,7 @@ import {
 } from '../types';
 import { ActionConstraints, ViewConstraints, ShortcutConstraints } from '../App';
 import { ContextMissingPropertyError } from '../errors';
+import { NonListenerMiddlewareArgs } from '../types/middleware';
 
 /**
  * Middleware that filters out any event that isn't an action
@@ -263,7 +264,7 @@ export function matchEventType(type: string): Middleware<SlackEventMiddlewareArg
  };
 }
 
-export function ignoreSelf(): Middleware<AnyMiddlewareArgs> {
+export function ignoreSelf(): Middleware<NonListenerMiddlewareArgs> {
  return async (args) => {
  // When context does not have a botId in it, then this middleware cannot perform its job. Bail immediately.
  if (args.context.botId === undefined) {
@@ -384,7 +385,7 @@ function isViewBody(
 }
 
 function isEventArgs(
- args: AnyMiddlewareArgs,
-): args is SlackEventMiddlewareArgs {
+ args: NonListenerMiddlewareArgs,
+): args is NonListenerMiddlewareArgs & SlackEventMiddlewareArgs {
  return (args as SlackEventMiddlewareArgs).event !== undefined;
 }

src/types/middleware.ts

@@ -27,6 +27,20 @@ export interface Middleware<Args> {
  (args: Args & AllMiddlewareArgs): Promise<void>;
 }
 
+interface NextForSure {
+ body: any;
+ context: Context;
+ logger: Logger;
+ client: WebClient;
+ next: NextFn;
+}
+
+export type NonListenerMiddlewareArgs = AnyMiddlewareArgs & NextForSure;
+
+export interface NonListenerMiddleware {
+ (args: NonListenerMiddlewareArgs): Promise<void>;
+}
+
 export interface Context extends StringIndexed {
 }