diff --git a/chat_stream_test.go b/chat_stream_test.go
new file mode 100644
index 000000000..b385e7bed
--- /dev/null
+++ b/chat_stream_test.go
@@ -0,0 +1,148 @@
+package openai_test
+
+import (
+	. "github.com/sashabaranov/go-openai"
+	"github.com/sashabaranov/go-openai/internal/test"
+
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestCreateChatCompletionStream(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/event-stream")
+
+		// Send test responses
+		dataBytes := []byte{}
+		dataBytes = append(dataBytes, []byte("event: message\n")...)
+		//nolint:lll
+		data := `{"id":"1","object":"completion","created":1598069254,"model":"gpt-3.5-turbo","choices":[{"index":0,"delta":{"content":"response1"},"finish_reason":"max_tokens"}]}`
+		dataBytes = append(dataBytes, []byte("data: "+data+"\n\n")...)
+
+		dataBytes = append(dataBytes, []byte("event: message\n")...)
+		//nolint:lll
+		data = `{"id":"2","object":"completion","created":1598069255,"model":"gpt-3.5-turbo","choices":[{"index":0,"delta":{"content":"response2"},"finish_reason":"max_tokens"}]}`
+		dataBytes = append(dataBytes, []byte("data: "+data+"\n\n")...)
+
+		dataBytes = append(dataBytes, []byte("event: done\n")...)
+		dataBytes = append(dataBytes, []byte("data: [DONE]\n\n")...)
+
+		_, err := w.Write(dataBytes)
+		if err != nil {
+			t.Errorf("Write error: %s", err)
+		}
+	}))
+	defer server.Close()
+
+	// Client portion of the test
+	config := DefaultConfig(test.GetTestToken())
+	config.BaseURL = server.URL + "/v1"
+	config.HTTPClient.Transport = &tokenRoundTripper{
+		test.GetTestToken(),
+		http.DefaultTransport,
+	}
+
+	client := NewClientWithConfig(config)
+	ctx := context.Background()
+
+	request := ChatCompletionRequest{
+		MaxTokens: 5,
+		Model:     GPT3Dot5Turbo,
+		Messages: []ChatCompletionMessage{
+			{
+				Role:    ChatMessageRoleUser,
+				Content: "Hello!",
+			},
+		},
+		Stream: true,
+	}
+
+	stream, err := client.CreateChatCompletionStream(ctx, request)
+	if err != nil {
+		t.Errorf("CreateCompletionStream returned error: %v", err)
+	}
+	defer stream.Close()
+
+	expectedResponses := []ChatCompletionStreamResponse{
+		{
+			ID:      "1",
+			Object:  "completion",
+			Created: 1598069254,
+			Model:   GPT3Dot5Turbo,
+			Choices: []ChatCompletionStreamChoice{
+				{
+					Delta: ChatCompletionStreamChoiceDelta{
+						Content: "response1",
+					},
+					FinishReason: "max_tokens",
+				},
+			},
+		},
+		{
+			ID:      "2",
+			Object:  "completion",
+			Created: 1598069255,
+			Model:   GPT3Dot5Turbo,
+			Choices: []ChatCompletionStreamChoice{
+				{
+					Delta: ChatCompletionStreamChoiceDelta{
+						Content: "response2",
+					},
+					FinishReason: "max_tokens",
+				},
+			},
+		},
+	}
+
+	for ix, expectedResponse := range expectedResponses {
+		b, _ := json.Marshal(expectedResponse)
+		t.Logf("%d: %s", ix, string(b))
+
+		receivedResponse, streamErr := stream.Recv()
+		if streamErr != nil {
+			t.Errorf("stream.Recv() failed: %v", streamErr)
+		}
+		if !compareChatResponses(expectedResponse, receivedResponse) {
+			t.Errorf("Stream response %v is %v, expected %v", ix, receivedResponse, expectedResponse)
+		}
+	}
+
+	_, streamErr := stream.Recv()
+	if !errors.Is(streamErr, io.EOF) {
+		t.Errorf("stream.Recv() did not return EOF in the end: %v", streamErr)
+	}
+}
+
+// Helper funcs.
+func compareChatResponses(r1, r2 ChatCompletionStreamResponse) bool {
+	if r1.ID != r2.ID || r1.Object != r2.Object || r1.Created != r2.Created || r1.Model != r2.Model {
+		return false
+	}
+	if len(r1.Choices) != len(r2.Choices) {
+		return false
+	}
+	for i := range r1.Choices {
+		if !compareChatStreamResponseChoices(r1.Choices[i], r2.Choices[i]) {
+			return false
+		}
+	}
+	return true
+}
+
+func compareChatStreamResponseChoices(c1, c2 ChatCompletionStreamChoice) bool {
+	if c1.Index != c2.Index {
+		return false
+	}
+	if c1.Delta.Content != c2.Delta.Content {
+		return false
+	}
+	if c1.FinishReason != c2.FinishReason {
+		return false
+	}
+	return true
+}
diff --git a/chat_test.go b/chat_test.go
new file mode 100644
index 000000000..5c03ebf7b
--- /dev/null
+++ b/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
+}