add chatgpt logic tests (#135)

* add chatgpt logic tests

* lint

chat_test.go

@@ -0,0 +1,132 @@
+package openai_test
+
+import (
+	. "github.com/sashabaranov/go-openai"
+	"github.com/sashabaranov/go-openai/internal/test"
+
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestChatCompletionsWrongModel(t *testing.T) {
+	config := DefaultConfig("whatever")
+	config.BaseURL = "http://localhost/v1"
+	client := NewClientWithConfig(config)
+	ctx := context.Background()
+
+	req := ChatCompletionRequest{
+		MaxTokens: 5,
+		Model:     "ada",
+		Messages: []ChatCompletionMessage{
+			{
+				Role:    ChatMessageRoleUser,
+				Content: "Hello!",
+			},
+		},
+	}
+	_, err := client.CreateChatCompletion(ctx, req)
+	if !errors.Is(err, ErrChatCompletionInvalidModel) {
+		t.Fatalf("CreateChatCompletion should return wrong model error, but returned: %v", err)
+	}
+}
+
+// TestCompletions Tests the completions endpoint of the API using the mocked server.
+func TestChatCompletions(t *testing.T) {
+	server := test.NewTestServer()
+	server.RegisterHandler("/v1/chat/completions", handleChatCompletionEndpoint)
+	// create the test server
+	var err error
+	ts := server.OpenAITestServer()
+	ts.Start()
+	defer ts.Close()
+
+	config := DefaultConfig(test.GetTestToken())
+	config.BaseURL = ts.URL + "/v1"
+	client := NewClientWithConfig(config)
+	ctx := context.Background()
+
+	req := ChatCompletionRequest{
+		MaxTokens: 5,
+		Model:     GPT3Dot5Turbo,
+		Messages: []ChatCompletionMessage{
+			{
+				Role:    ChatMessageRoleUser,
+				Content: "Hello!",
+			},
+		},
+	}
+	_, err = client.CreateChatCompletion(ctx, req)
+	if err != nil {
+		t.Fatalf("CreateChatCompletion error: %v", err)
+	}
+}
+
+// handleChatCompletionEndpoint Handles the ChatGPT completion endpoint by the test server.
+func handleChatCompletionEndpoint(w http.ResponseWriter, r *http.Request) {
+	var err error
+	var resBytes []byte
+
+	// completions only accepts POST requests
+	if r.Method != "POST" {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+	}
+	var completionReq ChatCompletionRequest
+	if completionReq, err = getChatCompletionBody(r); err != nil {
+		http.Error(w, "could not read request", http.StatusInternalServerError)
+		return
+	}
+	res := ChatCompletionResponse{
+		ID:      strconv.Itoa(int(time.Now().Unix())),
+		Object:  "test-object",
+		Created: time.Now().Unix(),
+		// would be nice to validate Model during testing, but
+		// this may not be possible with how much upkeep
+		// would be required / wouldn't make much sense
+		Model: completionReq.Model,
+	}
+	// create completions
+	for i := 0; i < completionReq.N; i++ {
+		// generate a random string of length completionReq.Length
+		completionStr := strings.Repeat("a", completionReq.MaxTokens)
+
+		res.Choices = append(res.Choices, ChatCompletionChoice{
+			Message: ChatCompletionMessage{
+				Role:    ChatMessageRoleAssistant,
+				Content: completionStr,
+			},
+			Index: i,
+		})
+	}
+	inputTokens := numTokens(completionReq.Messages[0].Content) * completionReq.N
+	completionTokens := completionReq.MaxTokens * completionReq.N
+	res.Usage = Usage{
+		PromptTokens:     inputTokens,
+		CompletionTokens: completionTokens,
+		TotalTokens:      inputTokens + completionTokens,
+	}
+	resBytes, _ = json.Marshal(res)
+	fmt.Fprintln(w, string(resBytes))
+}
+
+// getChatCompletionBody Returns the body of the request to create a completion.
+func getChatCompletionBody(r *http.Request) (ChatCompletionRequest, error) {
+	completion := ChatCompletionRequest{}
+	// read the request body
+	reqBody, err := io.ReadAll(r.Body)
+	if err != nil {
+		return ChatCompletionRequest{}, err
+	}
+	err = json.Unmarshal(reqBody, &completion)
+	if err != nil {
+		return ChatCompletionRequest{}, err
+	}
+	return completion, nil
+}