testland/grpc-mock
Wraps gRPC server-mocking patterns for client-side tests: Go bufconn (in-memory net.Listener via google.golang.org/grpc/test/bufconn) + mockgen-generated interface mocks, Python pytest-grpc fixtures + unittest.mock patching of stubs, JVM grpc-mock library / in-process gRPC server (InProcessServerBuilder), Node @grpc/grpc-js fake server with NewServer-on-port-0. Also carries the interceptor-layer test patterns (Go / Java / grpc-js auth, retry, logging, error-mapping, chained ordering via a spy handler) in references/interceptors.md. Use when writing client-side tests that need a controllable gRPC server response (success cases, error cases, timeouts, single-response error injection) without spinning up a real backend, or when testing a gRPC interceptor. For multi-message streaming-sequence tests (server-streaming, bidi), use grpc-streaming-test-author instead. Distinct from grpcurl-cli (ad-hoc CLI invocation against a real server) and ghz-load (perf against a real server).
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grpc-js-interceptors.mdreferences/
grpc-js client interceptor tests
@grpc/grpc-js exposes client interceptors as a channel option. The
package README confirms "Client Interceptors" as a supported feature at
github.com/grpc/grpc-node/tree/master/packages/grpc-js.
An interceptor is a function (options, nextCall) => InterceptingCall.
Client interceptor - auth-header injection
Test an auth-header injector by building an InterceptingCall with a
RequesterBuilder that captures the outbound metadata:
import * as grpc from "@grpc/grpc-js";
import { InterceptingCall, InterceptorOptions, NextCall } from "@grpc/grpc-js";
function authInterceptor(token: string) {
return (options: InterceptorOptions, nextCall: NextCall): InterceptingCall => {
return new InterceptingCall(nextCall(options), {
start(metadata, listener, next) {
metadata.add("authorization", `Bearer ${token}`);
next(metadata, listener);
},
});
};
}
// Test using a spy on the nextCall layer
test("authInterceptor injects Authorization header", () => {
let capturedMetadata: grpc.Metadata | undefined;
const fakeNext: NextCall = (_options) =>
new InterceptingCall(null as any, {
start(metadata, _listener, _next) {
capturedMetadata = metadata;
},
});
const interceptorFn = authInterceptor("my-token");
const call = interceptorFn({} as InterceptorOptions, fakeNext);
call.start(new grpc.Metadata(), {} as grpc.Listener);
expect(capturedMetadata?.get("authorization")).toEqual(["Bearer my-token"]);
});Register on a channel:
const client = new UserServiceClient(address, credentials, {
interceptors: [authInterceptor("my-token")],
});