Add sample test strategy

samples/README.md

@@ -24,6 +24,7 @@ In this case, the bot has commands to start a conversation, which then causes it
 ## samples/echoBot
 
 This bot is as basic as it gets - it simply repeats everything you say.
+The main_test.go file contains example code to demonstrate how to implement the gotgbot.BotClient interface for it to be used in tests.
 
 ## samples/echoMultiBot
 

samples/echoBot/main.go

@@ -14,6 +14,7 @@ import (
 )
 
 // This bot is as basic as it gets - it simply repeats everything you say.
+// The main_test.go file contains example code to demonstrate how to implement the gotgbot.BotClient interface for it to be used in tests.
 func main() {
 	// Get token from the environment variable
 	token := os.Getenv("TOKEN")

samples/echoBot/main_test.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"math/rand"
+	"testing"
+
+	"github.com/PaulSonOfLars/gotgbot/v2"
+	"github.com/PaulSonOfLars/gotgbot/v2/ext"
+)
+
+type RequestFunc func(ctx context.Context, token string, method string, params map[string]string, data map[string]gotgbot.FileReader, opts *gotgbot.RequestOpts) (json.RawMessage, error)
+
+// We define a TestBotClient which allows us to overwrite a single method on a per-test basis; meaning each test can verify specific behaviour.
+type TestBotClient struct {
+	RequestFunc RequestFunc
+}
+
+func (b TestBotClient) GetAPIURL(opts *gotgbot.RequestOpts) string {
+	// implement me if needed
+	panic("not implemented")
+}
+
+func (b TestBotClient) FileURL(token string, tgFilePath string, opts *gotgbot.RequestOpts) string {
+	// implement me if needed
+	panic("not implemented")
+}
+
+// Define wrapper around existing RequestWithContext method.
+func (b TestBotClient) RequestWithContext(ctx context.Context, token string, method string, params map[string]string, data map[string]gotgbot.FileReader, opts *gotgbot.RequestOpts) (json.RawMessage, error) {
+	if b.RequestFunc == nil {
+		panic("no requestfunc provided for test")
+	}
+	return b.RequestFunc(ctx, token, method, params, data, opts)
+}
+
+func NewBotClient(f RequestFunc) gotgbot.BotClient {
+	return TestBotClient{
+		RequestFunc: f,
+	}
+}
+
+func Test_echo(t *testing.T) {
+	const echoMessage = "Hello"
+	sendMessageCount := 0
+
+	b := testBot(func(ctx context.Context, token string, method string, params map[string]string, data map[string]gotgbot.FileReader, opts *gotgbot.RequestOpts) (json.RawMessage, error) {
+		if method != "sendMessage" {
+			t.Fatalf("Only expected API calls to sendMessage, got %s", method)
+		}
+
+		sentText := params["text"]
+		if sentText != echoMessage {
+			t.Errorf("expected text to be %s, got %s", echoMessage, sentText)
+		}
+
+		sendMessageCount++
+		return json.Marshal(gotgbot.Message{
+			MessageId: rand.Int63(),
+			Text:      sentText,
+		})
+	})
+
+	err := echo(b, ext.NewContext(b, testMessage(echoMessage), nil))
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func testBot(f RequestFunc) *gotgbot.Bot {
+	id := rand.Int63()
+
+	return &gotgbot.Bot{
+		Token: fmt.Sprintf("%d:TEST", id),
+		User: gotgbot.User{
+			Id:        id,
+			IsBot:     true,
+			FirstName: "Testing",
+			Username:  "TestBot",
+		},
+		BotClient: NewBotClient(f),
+	}
+}
+
+func testMessage(text string) *gotgbot.Update {
+	return &gotgbot.Update{
+		UpdateId: rand.Int63(),
+		Message: &gotgbot.Message{
+			MessageId: rand.Int63(),
+			Text:      text,
+			// populate other fields as needed
+		},
+	}
+
+}