Fix typing issues in handler arguments and introduce generic type

These issues became apparent because `typescript@next` correctly types `Function#bind` instead of returning `any`.

packages/apollo-server-cloudflare/src/cloudflareApollo.ts

@@ -1,5 +1,6 @@
 import {
   GraphQLOptions,
+  ServerOptionsFunction,
   HttpQueryError,
   runHttpQuery,
 } from 'apollo-server-core';
@@ -11,7 +12,11 @@ import { Request, Response, URL } from 'apollo-server-env';
 // - simple, fast and secure
 //
 
-export function graphqlCloudflare(options: GraphQLOptions) {
+export type CloudflareOptionsFunction = ServerOptionsFunction<[Request]>;
+
+export function graphqlCloudflare(
+  options: GraphQLOptions | CloudflareOptionsFunction,
+) {
   if (!options) {
     throw new Error('Apollo Server requires options.');
   }

packages/apollo-server-core/src/graphqlOptions.ts

@@ -55,13 +55,13 @@ export interface PersistedQueryOptions {
 
 export default GraphQLServerOptions;
 
-export async function resolveGraphqlOptions(
+export async function resolveGraphqlOptions<HandlerArguments extends any[]>(
   options:
     | GraphQLServerOptions
     | ((
-        ...args: Array<any>
+        ...args: HandlerArguments
       ) => Promise<GraphQLServerOptions> | GraphQLServerOptions),
-  ...args: Array<any>
+  ...args: HandlerArguments
 ): Promise<GraphQLServerOptions> {
   if (typeof options === 'function') {
     return await options(...args);

packages/apollo-server-core/src/runHttpQuery.ts

@@ -17,7 +17,7 @@ import {
 } from './requestPipeline';
 import { CacheControlExtensionOptions } from 'apollo-cache-control';
 
-export interface HttpQueryRequest {
+export interface HttpQueryRequest<HandlerArguments extends any[]> {
   method: string;
   // query is either the POST body or the GET query string map.  In the GET
   // case, all values are strings and need to be parsed as JSON; in the POST
@@ -27,7 +27,7 @@ export interface HttpQueryRequest {
   query: Record<string, any> | Array<Record<string, any>>;
   options:
     | GraphQLOptions
-    | ((...args: Array<any>) => Promise<GraphQLOptions> | GraphQLOptions);
+    | ((...args: HandlerArguments) => Promise<GraphQLOptions> | GraphQLOptions);
   request: Pick<Request, 'url' | 'method' | 'headers'>;
 }
 
@@ -90,9 +90,9 @@ function throwHttpGraphQLError<E extends Error>(
   );
 }
 
-export async function runHttpQuery(
-  handlerArguments: Array<any>,
-  request: HttpQueryRequest,
+export async function runHttpQuery<HandlerArguments extends any[]>(
+  handlerArguments: HandlerArguments,
+  request: HttpQueryRequest<HandlerArguments>,
 ): Promise<HttpQueryResponse> {
   let options: GraphQLOptions;
   const debugDefault =
@@ -178,7 +178,7 @@ export async function processHTTPRequest<TContext>(
     context: TContext;
     cache: NonNullable<GraphQLOptions<TContext>['cache']>;
   },
-  httpRequest: HttpQueryRequest,
+  httpRequest: HttpQueryRequest<any>,
 ): Promise<HttpQueryResponse> {
   let requestPayload;
 

packages/apollo-server-core/src/types.ts

@@ -24,6 +24,12 @@ export type ContextFunction<T = any> = (
   context: Context<T>,
 ) => Promise<Context<T>>;
 
+type ValueOrPromise<T> = T | Promise<T>;
+
+export type ServerOptionsFunction<HandlerArguments extends any[]> = (
+  ...args: HandlerArguments
+) => ValueOrPromise<GraphQLOptions>;
+
 export interface SubscriptionServerOptions {
   path: string;
   keepAlive?: number;

packages/apollo-server-core/tsconfig.test.json

@@ -1,9 +0,0 @@
-{
-  "extends": "../../tsconfig.test.base",
-  "include": ["src/**/__tests__", "src/**/__mocks__"],
-  "references": [
-    { "path": "./tsconfig.json" },
-    { "path": "./tsconfig.requestPipelineAPI.json" },
-    { "path": "../apollo-server-integration-testsuite" }
-  ]
-}

packages/apollo-server-express/src/expressApollo.ts

@@ -1,16 +1,15 @@
 import express from 'express';
 import {
   GraphQLOptions,
+  ServerOptionsFunction,
   HttpQueryError,
   runHttpQuery,
   convertNodeHttpToRequest,
 } from 'apollo-server-core';
 
-export interface ExpressGraphQLOptionsFunction {
-  (req?: express.Request, res?: express.Response):
-    | GraphQLOptions
-    | Promise<GraphQLOptions>;
-}
+export type ExpressGraphQLOptionsFunction = ServerOptionsFunction<
+  [express.Request, express.Response]
+>;
 
 // Design principles:
 // - there is just one way allowed: POST request with JSON body. Nothing else.

packages/apollo-server-hapi/src/hapiApollo.ts

@@ -1,7 +1,8 @@
 import Boom from 'boom';
-import { Server, Request, RouteOptions } from 'hapi';
+import { Server, Request, RouteOptions, ResponseToolkit } from 'hapi';
 import {
   GraphQLOptions,
+  ServerOptionsFunction,
   runHttpQuery,
   convertNodeHttpToRequest,
 } from 'apollo-server-core';
@@ -16,9 +17,9 @@ export interface IPlugin {
   register: IRegister;
 }
 
-export interface HapiOptionsFunction {
-  (request?: Request): GraphQLOptions | Promise<GraphQLOptions>;
-}
+export type HapiOptionsFunction = ServerOptionsFunction<
+  [Request, ResponseToolkit]
+>;
 
 export interface HapiPluginOptions {
   path: string;

packages/apollo-server-koa/src/koaApollo.ts

@@ -1,14 +1,13 @@
 import Koa from 'koa';
 import {
   GraphQLOptions,
+  ServerOptionsFunction,
   HttpQueryError,
   runHttpQuery,
   convertNodeHttpToRequest,
 } from 'apollo-server-core';
 
-export interface KoaGraphQLOptionsFunction {
-  (ctx: Koa.Context): GraphQLOptions | Promise<GraphQLOptions>;
-}
+export type KoaGraphQLOptionsFunction = ServerOptionsFunction<[Koa.Context]>;
 
 export interface KoaHandler {
   (ctx: Koa.Context, next): void;

packages/apollo-server-lambda/src/lambdaApollo.ts

@@ -1,16 +1,15 @@
 import lambda from 'aws-lambda';
 import {
   GraphQLOptions,
+  ServerOptionsFunction,
   HttpQueryError,
   runHttpQuery,
 } from 'apollo-server-core';
 import { Headers } from 'apollo-server-env';
 
-export interface LambdaGraphQLOptionsFunction {
-  (event: lambda.APIGatewayProxyEvent, context: lambda.Context):
-    | GraphQLOptions
-    | Promise<GraphQLOptions>;
-}
+export type LambdaGraphQLOptionsFunction = ServerOptionsFunction<
+  [lambda.APIGatewayProxyEvent, lambda.Context]
+>;
 
 export function graphqlLambda(
   options: GraphQLOptions | LambdaGraphQLOptionsFunction,

packages/apollo-server-micro/src/microApollo.ts

@@ -1,18 +1,20 @@
 import {
   GraphQLOptions,
+  ServerOptionsFunction,
   runHttpQuery,
   convertNodeHttpToRequest,
 } from 'apollo-server-core';
 import { send, json, RequestHandler } from 'micro';
 import url from 'url';
-import { IncomingMessage, ServerResponse } from 'http';
+import { ServerResponse } from 'http';
 
 import { MicroRequest } from './types';
 
 // Allowed Micro Apollo Server options.
-export interface MicroGraphQLOptionsFunction {
-  (req?: IncomingMessage): GraphQLOptions | Promise<GraphQLOptions>;
-}
+
+export type MicroGraphQLOptionsFunction = ServerOptionsFunction<
+  [MicroRequest, ServerResponse]
+>;
 
 // Utility function used to set multiple headers on a response object.
 function setHeaders(res: ServerResponse, headers: Object): void {