I am doing a lot of manual exploratory testing of microservices after a feature story has been delivered. To do that, I need to simulate different responses from a gRPC API. So I would like to start a docker image with my microservice, and point it at a gRPC API that I can control and simulate different types of responses to test different sad-path scenarios.
How can I create mocks of gRPC APIs?
You can use an API simulation/mocking tool. Currently the only tool on that list that supports gRPC is Traffic Parrot.
Here is a video demo of how you can use the tool to record and replay gRPC messages.
We have recently added a tutorial on how to mock gRPC responses over the wire given a proto file.
You can also find information on how to record and replay over the wire in the documentation.
There are multiple tools available on GitHub. You can find related repositories using the corresponding grpc-mock topic link.
Another possible solution is to use a cloud solution such as mock.qa. Mock.qa is a cloud service (SaaS) that provides a production-ready gRPC mocking server and supports both gRPC and gRPC-web protocols.
For example, the Greeter service with the following .proto file:
syntax = "proto3";
package demo.greet;
// The greeting service definition.
service Greeter {
// Sends a greeting
rpc SayHello (HelloRequest) returns (HelloReply);
}
// The request message containing the user's name.
message HelloRequest {
string name = 1;
}
// The response message containing the greetings
message HelloReply {
string message = 1;
}
can be mocked using the following mock.qa configuration file:
---
fileVersion: v1
serverName: Greet
protoFile: "/greet.proto"
# Incoming request matching is done in the order of definition,
# sequentially, from the first one to the last one,
# once match is found, the processing stops
calls:
# First, we try to match a call to Joe
- method: SayHello
request:
body:
Name: "Joe"
response:
body:
Message: Hello Joe!
status: OK
# Then, we try to match a call to Kelly
- method: SayHello
request:
body:
Name: "Kelly"
response:
body:
Message: Hello Kelly!
status: OK
# And if no match, fall back to NotFound
- method: SayHello
# "request" section is optional and may absent
# - if "request" section is absent
# then any call of the method is matched
response:
statusCode: NOT_FOUND
statusDetails: Name not found