@improbable-eng/grpc-web-fake-transport

Fake Transport for use with @improbable-eng/grpc-web.

Usage

FakeTransportBuilder builds a Transport that can be configured to send preset headers, messages, and trailers for testing.

By default the Transport that FakeTranportBuilder.build() generates will trigger all of the specified response behaviours (.withHeaders(metadata), .withMessages([msgOne, msgTwo]), .withTrailers(metadata)) when the client has finished sending.

This is usually the desired flow as all of the response behaviour is triggered only after the client has finished sending as would most commonly occur in production usage.

However, in the case of bi-directional or other complex usage it can be helpful to use .withManualTrigger() to disable automatic sending of messages or headers/trailers and trigger the sending manually using sendHeaders(), sendMessages() and sendTrailers().

With Service Stubs generated by ts-protoc-gen

import { FakeTransportBuilder } from '@improbable-eng/grpc-web-fake-transport';

const fakeTransport = new FakeTransportBuilder()
  .withMessages([ new PingResponse() ])
  .build();

const client = new PingServiceClient("https://example.com", {
  transport: fakeTransport
});

client.DoPing(/* ... */);

With grpc-web

import { grpc } from '@improbable-eng/grpc-web';
import { FakeTransportBuilder } from '@improbable-eng/grpc-web-fake-transport';

const fakeTransport = new FakeTransportBuilder()
  .withMessages([ new PingResponse() ])
  .build();

grpc.invoke(PingService.DoPing, {
  host: "https://example.com",
  transport: fakeTransport,
  /* ... */
});

With withManualTrigger()

import { grpc } from '@improbable-eng/grpc-web';
import { FakeTransportBuilder } from '@improbable-eng/grpc-web-fake-transport';

const fakeTransport = new FakeTransportBuilder()
  .withManualTrigger()
  .withHeaders(new grpc.Metadata({ headerKey: "value" }))
  .withMessages([ new PingResponse() ])
  .withTrailers(new grpc.Metadata({ trailerKey: "value" }))
  .build();

grpc.invoke(PingService.DoPing, {
  host: "https://example.com",
  transport: fakeTransport,
  /* ... */
});

// Manually trigger the response behaviours
fakeTransport.sendHeaders();
fakeTransport.sendMessages();
fakeTransport.sendTrailers();

Alternatively replace the Default Transport when initialising your tests:

import { grpc } from "@improbable-eng/grpc-web";
import { NodeHttpTransport } from "@improbable-eng/grpc-web-fake-transport";

// Do this first, before you make any grpc requests!
grpc.setDefaultTransport(fakeTransport);