Throw error object on HTTP error

Fixes grpc-ecosystem#15

generator/template.go

@@ -99,7 +99,10 @@ export function fetchReq<I, O>(path: string, init?: InitReq): Promise<O> {
 
   const url = pathPrefix ? ` + "`${pathPrefix}${path}`" + ` : path
 
-  return fetch(url, req).then(r => r.json()) as Promise<O>
+  return fetch(url, req).then(r => r.json().then((body: O) => {
+    if (!r.ok) { throw body; }
+    return body;
+  })) as Promise<O>
 }
 
 // NotifyStreamEntityArrival is a callback that will be called on streaming entity arrival

integration_tests/integration_test.ts

@@ -19,6 +19,16 @@ describe("test grpc-gateway-ts communication", () => {
     expect(result.result).to.equal(200)
   })
 
+  it("failing unary request", async () => {
+    try {
+      await CounterService.FailingIncrement({ counter: 199 }, { pathPrefix: "http://localhost:8081" }); 
+      expect.fail("expected call to throw");
+    } catch (e) {
+      expect(e).to.have.property("message", "this increment does not work")
+      expect(e).to.have.property("code", 14);
+    }
+  })
+
   it('streaming request', async () => {
     const response = [] as number[]
     await CounterService.StreamingIncrements({ counter: 1 }, (resp) => response.push(resp.result), { pathPrefix: "http://localhost:8081" })

integration_tests/service.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"time"
 
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/types/known/emptypb"
 )
 
@@ -21,6 +23,10 @@ func (r *RealCounterService) Increment(c context.Context, req *UnaryRequest) (*U
 	}, nil
 }
 
+func (r *RealCounterService) FailingIncrement(c context.Context, req *UnaryRequest) (*UnaryResponse, error) {
+	return nil, status.Errorf(codes.Unavailable, "this increment does not work")
+}
+
 func (r *RealCounterService) StreamingIncrements(req *StreamingRequest, service CounterService_StreamingIncrementsServer) error {
 	times := 5
 	counter := req.Counter