Testing: mock the client

Because mistral.Client is just an interface, it's possible to mock it. Here, I'll give you an example with gomock, but you can use any mocking framework.

First, install the library:

go install go.uber.org/mock/mockgen@latest

Gomock works with code generation. Start by creating an gen.go file at your project's root directory:

touch gen.go

Then, describe in this file what code you want to generate and where. Here's an example:

package main_test

import _ "go.uber.org/mock/gomock"

//go:generate mockgen -package mocks -destination mocks/client.go github.com/thomas-marquis/mistral-client/mistral Client

Run the command go generate ./... to generate the mock's code. A mocks/client.go file will be created.

Eventually, you can use this mock in your tests:

package my_test

import (
    "context"
    "reflect"
    "testing"

    "github.com/golang/mock/gomock"
    "github.com/thomas-marquis/mistral-client/mistral"
    "<your_project_package_id>/mocks"
)

var (
    ctxType = reflect.TypeOf((*context.Context)(nil)).Elem()
)

func TestSomething(t *testing.T) {
    mockCtrl := gomock.NewController(t)

    mockClient := mocks.NewMockClient(mockCtrl)
    mockClient.EXPECT().
        ChatCompletion(
            gomock.AssignableToTypeOf(ctxType),
            gomock.Eq(&mistralclient.ChatCompletionRequest{
                CompletionConfig: mistralclient.CompletionConfig{
                    ResponseFormat: &mistralclient.ResponseFormat{Type: "text"},
                },
                Model:    "mistral-small-latest",
                Messages: messages,
            }),
        ).
        Return(&mistral.ChatCompletionResponse{
            Choices: []mistralclient.ChatCompletionChoice{
                {Message: mistralclient.NewAssistantMessageFromString("Hello simple human being!")},
            },
        }, nil)

    // Use mockClient in your tests
}