Add tests for strongly typed function wrappers

Author: garethgeorge

src/function_registry.ts

@@ -18,7 +18,7 @@ import {
   HandlerFunction,
   TypedHandlerFunction,
   InvocationFormat,
-  JsonInvocationSerializer,
+  JsonInvocationFormat,
 } from './functions';
 import {SignatureType} from './types';
 
@@ -75,7 +75,7 @@ export const isValidFunctionName = (functionName: string): boolean => {
 export const getRegisteredFunction = (
   functionName: string
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-): RegisteredFunction<any> | undefined => {
+): RegisteredFunction<any, any> | undefined => {
   return registrationContainer.get(functionName);
 };
 
@@ -103,15 +103,19 @@ export const cloudEvent = <T = unknown>(
 };
 
 
-
+/**
+ * Register a function that handles strongly typed invocations.
+ * @param functionName - the name of the function 
+ * @param handler - the function to trigger.
+ */
 export const typed = <T, U>(
   functionName: string,
   handler: TypedHandlerFunction<T, U>['handler'] | TypedHandlerFunction<T, U>
 ): void => {
   if (handler instanceof Function) {
     handler = {
       handler,
-      format: new JsonInvocationSerializer<T, U>(),
+      format: new JsonInvocationFormat<T, U>(),
     }
   }
   register(functionName, 'typed', handler);

src/function_wrappers.ts

@@ -27,7 +27,6 @@ import {
   CloudEventFunctionWithCallback,
   HandlerFunction,
   TypedHandlerFunction,
-  InvocationFormat,
   InvocationRequest,
   InvocationResponse
 } from './functions';
@@ -106,18 +105,25 @@ const parseBackgroundEvent = (req: Request): {data: {}; context: Context} => {
 const wrapHttpFunction = (execute: HttpFunction): RequestHandler => {
   return (req: Request, res: Response) => {
     const d = domain.create();
-    // Catch unhandled errors originating from this request.
-    d.on('error', err => {
+    const errorHandler = (err: Error) => {
       if (res.locals.functionExecutionFinished) {
         console.error(`Exception from a finished function: ${err}`);
       } else {
         res.locals.functionExecutionFinished = true;
-        sendCrashResponse({err, res});
+        sendCrashResponse({ err, res });
       }
-    });
+    };
+
+    // Catch unhandled errors originating from this request.
+    d.on('error', errorHandler);
+
     d.run(() => {
       process.nextTick(() => {
-        execute(req, res);
+        const ret = execute(req, res);
+        // Catch rejected promises if the function is async.
+        if (ret instanceof Promise) {
+          ret.catch(errorHandler);
+        }
       });
     });
   };
@@ -216,45 +222,41 @@ const wrapTypedFunction = (
   }
 
   class InvocationResponseImpl implements InvocationResponse {
-    constructor(private req: Response) { }
+    constructor(private res: Response) { }
 
     setHeader(key: string, value: string): void {
-      throw new Error('Method not implemented.');
+      this.res.set(key, value);
     }
     write(data: string | Buffer): void {
-      this.req.write(data);
+      this.res.write(data);
     }
     end(data: string | Buffer): void {
-      this.req.end(data);
+      this.res.end(data);
     }
   }
 
-  const handler: HttpFunction = async (req: Request, res: Response) => {
+  const typedHandlerWrapper: HttpFunction = async (req: Request, res: Response) => {
     let reqTyped: any;
     try {
       reqTyped = typedFunction.format.deserializeRequest(new InvocationRequestImpl(req));
-      if (reqTyped instanceof Promise) {
-        reqTyped = await reqTyped;
-      }
     } catch (err) {
+      console.log(err);
       sendCrashResponse({
         err, res,
         statusOverride: 400 // 400 Bad Request
       });
+      return;
     }
 
     let resTyped: any = typedFunction.handler(reqTyped);
     if (resTyped instanceof Promise) {
       resTyped = await resTyped;
     }
 
-    const maybePromise = typedFunction.format.serializeResponse(new InvocationResponseImpl(res), resTyped);
-    if (maybePromise instanceof Promise) {
-      await maybePromise;
-    }
+    typedFunction.format.serializeResponse(new InvocationResponseImpl(res), resTyped);
   }
 
-  return wrapHttpFunction(handler);
+  return wrapHttpFunction(typedHandlerWrapper);
 }
 
 /**
@@ -272,19 +274,21 @@ export const wrapUserFunction = <T = unknown>(
       return wrapHttpFunction(userFunction as HttpFunction);
     case 'event':
       // Callback style if user function has more than 2 arguments.
-      if (userFunction!.length > 2) {
+      if (userFunction instanceof Function && userFunction!.length > 2) {
         return wrapEventFunctionWithCallback(
           userFunction as EventFunctionWithCallback
         );
       }
       return wrapEventFunction(userFunction as EventFunction);
     case 'cloudevent':
-      if (userFunction!.length > 1) {
+      if (userFunction instanceof Function && userFunction!.length > 1) {
         // Callback style if user function has more than 1 argument.
         return wrapCloudEventFunctionWithCallback(
           userFunction as CloudEventFunctionWithCallback
         );
       }
       return wrapCloudEventFunction(userFunction as CloudEventFunction);
+    case 'typed':
+      return wrapTypedFunction(userFunction as TypedHandlerFunction);
   }
 };

src/functions.ts

@@ -152,7 +152,9 @@ export type Context = CloudFunctionsContext | CloudEvent<unknown>;
  * Invocation request interface describes the properties of an invocation.
  */
 export interface InvocationRequest {
+  /** Returns the request body as either a string or a Buffer if the body is binary. */
   body(): string | Buffer;
+  /** Header returns the value of the specified header */
   header(header: string): string | undefined;
 }
 
@@ -161,14 +163,20 @@ export interface InvocationRequest {
  * an invocation response.
  */
 export interface InvocationResponse {
+  /** Sets a header on the response. */
   setHeader(key: string, value: string): void;
+  /** Writes a chunk of data to the response. */
   write(data: string | Buffer): void;
+  /** Ends the response, must be called once at the end of writing. */
   end(data: string | Buffer): void;
 }
 
+/**
+ * The contract for a request deserializer and response serializer.
+ */
 export interface InvocationFormat<T, U> {
   /**
-   * 
+   *
    * @param request the request body as raw bytes
    * @param headers the headers received on the HTTP request as a map
    */
@@ -178,20 +186,30 @@ export interface InvocationFormat<T, U> {
    * @param response
    * @param responseHeaders mutable object providing headers that will be set on the response
    */
-  serializeResponse(responseWriter: InvocationResponse, response: U): void | Promise<void>;
+  serializeResponse(
+    responseWriter: InvocationResponse,
+    response: U
+  ): void | Promise<void>;
 }
 
-export class JsonInvocationSerializer<T, U> implements InvocationFormat<T, U> {
+/**
+ * Default invocation format for JSON requests.
+ */
+export class JsonInvocationFormat<T, U> implements InvocationFormat<T, U> {
   deserializeRequest(request: InvocationRequest): T {
-    if (!(typeof request.body === 'string')) {
-      throw new Error('Request Content-Type or encoding unsupported');
+    let body = request.body();
+    if (typeof body !== 'string') {
+      throw new Error("Unsupported Content-Type, expected application/json");
+    }
+    try {
+      return JSON.parse(body);
+    } catch (e) {
+      throw new Error("Failed to parse malformatted JSON in request: " + (e as SyntaxError).message)
     }
-    if
-    return JSON.parse(request.body);
   }
 
   serializeResponse(responseWriter: InvocationResponse, response: U): void {
     responseWriter.setHeader('content-type', 'application/json');
     responseWriter.end(JSON.stringify(response));
   }
-}
+}

src/index.ts

@@ -20,4 +20,4 @@ export * from './functions';
 /**
  * @public
  */
-export {http, cloudEvent} from './function_registry';
+export {http, cloudEvent, typed} from './function_registry';

src/server.ts

@@ -85,9 +85,20 @@ export function getServer(
   };
 
   // Apply middleware
-  app.use(bodyParser.json(cloudEventsBodySavingOptions));
-  app.use(bodyParser.json(defaultBodySavingOptions));
-  app.use(bodyParser.text(defaultBodySavingOptions));
+  if (functionSignatureType === 'typed') {
+    app.use(bodyParser.text({
+      limit: requestLimit,
+      type: '*/json',
+    }))
+    app.use(bodyParser.text({
+      limit: requestLimit,
+      type: 'text/*',
+    }))
+  } else {
+    app.use(bodyParser.json(cloudEventsBodySavingOptions));
+    app.use(bodyParser.json(defaultBodySavingOptions));
+    app.use(bodyParser.text(defaultBodySavingOptions));
+  }
   app.use(bodyParser.urlencoded(urlEncodedOptions));
   // The parser will process ALL content types so MUST come last.
   // Subsequent parsers will be skipped when one is matched.