feat(Grpc-Web): Add & export GrpcWebError type (#593)

* feat(Grpc-Web): Add & export GrpcWebError type

* refactor(GrpcWebError): Convert interface to a concrete error class

* refactor(GrpcWebError): Drop unneeded `Object.setPrototypeOf(this, GrpcWebError.prototype);` as ES5 is deprecated

integration/grpc-web-no-streaming-observable/example.ts

@@ -405,7 +405,8 @@ export class GrpcWebImpl {
         debug: this.options.debug,
         onEnd: (next) => {
           if (next.status !== 0) {
-            observer.error({ code: next.status, message: next.statusMessage });
+            const err = new GrpcWebError(next.statusMessage, next.status, next.trailers);
+            observer.error(err);
           } else {
             observer.next(next.message as any);
             observer.complete();
@@ -436,3 +437,9 @@ export type Exact<P, I extends P> = P extends Builtin
 function isSet(value: any): boolean {
   return value !== null && value !== undefined;
 }
+
+export class GrpcWebError extends Error {
+  constructor(message: string, public code: grpc.Code, public metadata: grpc.Metadata) {
+    super(message);
+  }
+}

integration/grpc-web-no-streaming/example.ts

@@ -405,9 +405,7 @@ export class GrpcWebImpl {
           if (response.status === grpc.Code.OK) {
             resolve(response.message);
           } else {
-            const err = new Error(response.statusMessage) as any;
-            err.code = response.status;
-            err.metadata = response.trailers;
+            const err = new GrpcWebError(response.statusMessage, response.status, response.trailers);
             reject(err);
           }
         },
@@ -436,3 +434,9 @@ export type Exact<P, I extends P> = P extends Builtin
 function isSet(value: any): boolean {
   return value !== null && value !== undefined;
 }
+
+export class GrpcWebError extends Error {
+  constructor(message: string, public code: grpc.Code, public metadata: grpc.Metadata) {
+    super(message);
+  }
+}

integration/grpc-web/client-ts.ts

@@ -35,8 +35,8 @@ async function main() {
   }
 
   const obs = client.ActiveUserSettingsStream({});
-  await obs.forEach(value => {
-    console.log("Got", value);
+  await obs.forEach((value) => {
+    console.log('Got', value);
   });
 }
 

integration/grpc-web/example-test.ts

@@ -1,5 +1,6 @@
-import { DashStateClientImpl } from './example';
+import { DashStateClientImpl, GrpcWebError, GrpcWebImpl } from './example';
 import { EMPTY } from 'rxjs';
+import { NodeHttpTransport } from '@improbable-eng/grpc-web-node-http-transport';
 
 describe('grpc-web', () => {
   it('at least compiles', () => {
@@ -27,7 +28,26 @@ describe('grpc-web', () => {
       invoke: jest.fn(),
     };
     const client = new DashStateClientImpl(rpc);
-    const call = () => client.ChangeUserSettingsStream(EMPTY)
-    expect(call).toThrowError("ts-proto does not yet support client streaming!")
+    const call = () => client.ChangeUserSettingsStream(EMPTY);
+    expect(call).toThrowError('ts-proto does not yet support client streaming!');
+  });
+
+  it('throws error of type GrpcWebError', async () => {
+    const client = new DashStateClientImpl(
+      new GrpcWebImpl('', {
+        transport: NodeHttpTransport(),
+      })
+    );
+
+    try {
+      await client.UserSettings({});
+    } catch (e) {
+      expect(e).toBeInstanceOf(GrpcWebError);
+
+      if (e instanceof GrpcWebError) {
+        expect(e.code).toBeDefined();
+        expect(e.metadata).toBeDefined();
+      }
+    }
   });
 });

integration/grpc-web/example.ts

@@ -845,9 +845,7 @@ export class GrpcWebImpl {
           if (response.status === grpc.Code.OK) {
             resolve(response.message);
           } else {
-            const err = new Error(response.statusMessage) as any;
-            err.code = response.status;
-            err.metadata = response.trailers;
+            const err = new GrpcWebError(response.statusMessage, response.status, response.trailers);
             reject(err);
           }
         },
@@ -916,3 +914,9 @@ export type Exact<P, I extends P> = P extends Builtin
 function isSet(value: any): boolean {
   return value !== null && value !== undefined;
 }
+
+export class GrpcWebError extends Error {
+  constructor(message: string, public code: grpc.Code, public metadata: grpc.Metadata) {
+    super(message);
+  }
+}

src/generate-grpc-web.ts

@@ -214,7 +214,7 @@ function generateGrpcWebImpl(ctx: Context, returnObservable: boolean, hasStreami
   if (returnObservable) {
     chunks.push(createObservableUnaryMethod(ctx));
   } else {
-    chunks.push(createPromiseUnaryMethod());
+    chunks.push(createPromiseUnaryMethod(ctx));
   }
 
   if (hasStreamingMethods) {
@@ -225,7 +225,7 @@ function generateGrpcWebImpl(ctx: Context, returnObservable: boolean, hasStreami
   return joinCode(chunks, { trim: false });
 }
 
-function createPromiseUnaryMethod(): Code {
+function createPromiseUnaryMethod(ctx: Context): Code {
   return code`
     unary<T extends UnaryMethodDefinitionish>(
       methodDesc: T,
@@ -248,9 +248,7 @@ function createPromiseUnaryMethod(): Code {
             if (response.status === grpc.Code.OK) {
               resolve(response.message);
             } else {
-              const err = new Error(response.statusMessage) as any;
-              err.code = response.status;
-              err.metadata = response.trailers;
+              const err = new ${ctx.utils.GrpcWebError}(response.statusMessage, response.status, response.trailers);
               reject(err);
             }
           },
@@ -281,7 +279,8 @@ function createObservableUnaryMethod(ctx: Context): Code {
           debug: this.options.debug,
           onEnd: (next) => {
             if (next.status !== 0) {
-              observer.error({ code: next.status, message: next.statusMessage });
+              const err = new ${ctx.utils.GrpcWebError}(next.statusMessage, next.status, next.trailers);
+              observer.error(err);
             } else {
               observer.next(next.message as any);
               observer.complete();

src/main.ts

@@ -316,7 +316,8 @@ export type Utils = ReturnType<typeof makeDeepPartial> &
   ReturnType<typeof makeByteUtils> &
   ReturnType<typeof makeLongUtils> &
   ReturnType<typeof makeComparisonUtils> &
-  ReturnType<typeof makeNiceGrpcServerStreamingMethodResult>;
+  ReturnType<typeof makeNiceGrpcServerStreamingMethodResult> &
+  ReturnType<typeof makeGrpcWebErrorClass>;
 
 /** These are runtime utility methods used by the generated code. */
 export function makeUtils(options: Options): Utils {
@@ -330,6 +331,7 @@ export function makeUtils(options: Options): Utils {
     ...longs,
     ...makeComparisonUtils(),
     ...makeNiceGrpcServerStreamingMethodResult(),
+    ...makeGrpcWebErrorClass(),
   };
 }
 
@@ -671,6 +673,21 @@ function makeNiceGrpcServerStreamingMethodResult() {
   return { NiceGrpcServerStreamingMethodResult };
 }
 
+function makeGrpcWebErrorClass() {
+  const GrpcWebError = conditionalOutput(
+    'GrpcWebError',
+    code`
+      export class GrpcWebError extends Error {
+        constructor(message: string, public code: grpc.Code, public metadata: grpc.Metadata) {
+          super(message);
+        }
+      }
+    `
+  );
+
+  return { GrpcWebError };
+}
+
 // Create the interface with properties
 function generateInterfaceDeclaration(
   ctx: Context,