Fix broken implementation AssistantModify implementation (sashabaranov#685)

* add custom marshaller, documentation and isolate tests

* fix linter

Author: qhenkart

Diff for: assistant.go

@@ -2,6 +2,7 @@ package openai
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/url"
@@ -21,7 +22,7 @@ type Assistant struct {
 	Description  *string         `json:"description,omitempty"`
 	Model        string          `json:"model"`
 	Instructions *string         `json:"instructions,omitempty"`
-	Tools        []AssistantTool `json:"tools,omitempty"`
+	Tools        []AssistantTool `json:"tools"`
 	FileIDs      []string        `json:"file_ids,omitempty"`
 	Metadata     map[string]any  `json:"metadata,omitempty"`
 
@@ -41,16 +42,41 @@ type AssistantTool struct {
 	Function *FunctionDefinition `json:"function,omitempty"`
 }
 
+// AssistantRequest provides the assistant request parameters.
+// When modifying the tools the API functions as the following:
+// If Tools is undefined, no changes are made to the Assistant's tools.
+// If Tools is empty slice it will effectively delete all of the Assistant's tools.
+// If Tools is populated, it will replace all of the existing Assistant's tools with the provided tools.
 type AssistantRequest struct {
 	Model        string          `json:"model"`
 	Name         *string         `json:"name,omitempty"`
 	Description  *string         `json:"description,omitempty"`
 	Instructions *string         `json:"instructions,omitempty"`
-	Tools        []AssistantTool `json:"tools"`
+	Tools        []AssistantTool `json:"-"`
 	FileIDs      []string        `json:"file_ids,omitempty"`
 	Metadata     map[string]any  `json:"metadata,omitempty"`
 }
 
+// MarshalJSON provides a custom marshaller for the assistant request to handle the API use cases
+// If Tools is nil, the field is omitted from the JSON.
+// If Tools is an empty slice, it's included in the JSON as an empty array ([]).
+// If Tools is populated, it's included in the JSON with the elements.
+func (a AssistantRequest) MarshalJSON() ([]byte, error) {
+	type Alias AssistantRequest
+	assistantAlias := &struct {
+		Tools *[]AssistantTool `json:"tools,omitempty"`
+		*Alias
+	}{
+		Alias: (*Alias)(&a),
+	}
+
+	if a.Tools != nil {
+		assistantAlias.Tools = &a.Tools
+	}
+
+	return json.Marshal(assistantAlias)
+}
+
 // AssistantsList is a list of assistants.
 type AssistantsList struct {
 	Assistants []Assistant `json:"data"`

Diff for: assistant_test.go

@@ -96,7 +96,7 @@ When asked a question, write and run Python code to answer the question.`
 				})
 				fmt.Fprintln(w, string(resBytes))
 			case http.MethodPost:
-				var request openai.AssistantRequest
+				var request openai.Assistant
 				err := json.NewDecoder(r.Body).Decode(&request)
 				checks.NoError(t, err, "Decode error")
 
@@ -163,44 +163,97 @@ When asked a question, write and run Python code to answer the question.`
 
 	ctx := context.Background()
 
-	_, err := client.CreateAssistant(ctx, openai.AssistantRequest{
-		Name:         &assistantName,
-		Description:  &assistantDescription,
-		Model:        openai.GPT4TurboPreview,
-		Instructions: &assistantInstructions,
+	t.Run("create_assistant", func(t *testing.T) {
+		_, err := client.CreateAssistant(ctx, openai.AssistantRequest{
+			Name:         &assistantName,
+			Description:  &assistantDescription,
+			Model:        openai.GPT4TurboPreview,
+			Instructions: &assistantInstructions,
+		})
+		checks.NoError(t, err, "CreateAssistant error")
 	})
-	checks.NoError(t, err, "CreateAssistant error")
 
-	_, err = client.RetrieveAssistant(ctx, assistantID)
-	checks.NoError(t, err, "RetrieveAssistant error")
+	t.Run("retrieve_assistant", func(t *testing.T) {
+		_, err := client.RetrieveAssistant(ctx, assistantID)
+		checks.NoError(t, err, "RetrieveAssistant error")
+	})
 
-	_, err = client.ModifyAssistant(ctx, assistantID, openai.AssistantRequest{
-		Name:         &assistantName,
-		Description:  &assistantDescription,
-		Model:        openai.GPT4TurboPreview,
-		Instructions: &assistantInstructions,
+	t.Run("delete_assistant", func(t *testing.T) {
+		_, err := client.DeleteAssistant(ctx, assistantID)
+		checks.NoError(t, err, "DeleteAssistant error")
 	})
-	checks.NoError(t, err, "ModifyAssistant error")
 
-	_, err = client.DeleteAssistant(ctx, assistantID)
-	checks.NoError(t, err, "DeleteAssistant error")
+	t.Run("list_assistant", func(t *testing.T) {
+		_, err := client.ListAssistants(ctx, &limit, &order, &after, &before)
+		checks.NoError(t, err, "ListAssistants error")
+	})
 
-	_, err = client.ListAssistants(ctx, &limit, &order, &after, &before)
-	checks.NoError(t, err, "ListAssistants error")
+	t.Run("create_assistant_file", func(t *testing.T) {
+		_, err := client.CreateAssistantFile(ctx, assistantID, openai.AssistantFileRequest{
+			FileID: assistantFileID,
+		})
+		checks.NoError(t, err, "CreateAssistantFile error")
+	})
 
-	_, err = client.CreateAssistantFile(ctx, assistantID, openai.AssistantFileRequest{
-		FileID: assistantFileID,
+	t.Run("list_assistant_files", func(t *testing.T) {
+		_, err := client.ListAssistantFiles(ctx, assistantID, &limit, &order, &after, &before)
+		checks.NoError(t, err, "ListAssistantFiles error")
 	})
-	checks.NoError(t, err, "CreateAssistantFile error")
 
-	_, err = client.ListAssistantFiles(ctx, assistantID, &limit, &order, &after, &before)
-	checks.NoError(t, err, "ListAssistantFiles error")
+	t.Run("retrieve_assistant_file", func(t *testing.T) {
+		_, err := client.RetrieveAssistantFile(ctx, assistantID, assistantFileID)
+		checks.NoError(t, err, "RetrieveAssistantFile error")
+	})
 
-	_, err = client.RetrieveAssistantFile(ctx, assistantID, assistantFileID)
-	checks.NoError(t, err, "RetrieveAssistantFile error")
+	t.Run("delete_assistant_file", func(t *testing.T) {
+		err := client.DeleteAssistantFile(ctx, assistantID, assistantFileID)
+		checks.NoError(t, err, "DeleteAssistantFile error")
+	})
 
-	err = client.DeleteAssistantFile(ctx, assistantID, assistantFileID)
-	checks.NoError(t, err, "DeleteAssistantFile error")
+	t.Run("modify_assistant_no_tools", func(t *testing.T) {
+		assistant, err := client.ModifyAssistant(ctx, assistantID, openai.AssistantRequest{
+			Name:         &assistantName,
+			Description:  &assistantDescription,
+			Model:        openai.GPT4TurboPreview,
+			Instructions: &assistantInstructions,
+		})
+		checks.NoError(t, err, "ModifyAssistant error")
+
+		if assistant.Tools != nil {
+			t.Errorf("expected nil got %v", assistant.Tools)
+		}
+	})
+
+	t.Run("modify_assistant_with_tools", func(t *testing.T) {
+		assistant, err := client.ModifyAssistant(ctx, assistantID, openai.AssistantRequest{
+			Name:         &assistantName,
+			Description:  &assistantDescription,
+			Model:        openai.GPT4TurboPreview,
+			Instructions: &assistantInstructions,
+			Tools:        []openai.AssistantTool{{Type: openai.AssistantToolTypeFunction}},
+		})
+		checks.NoError(t, err, "ModifyAssistant error")
+
+		if assistant.Tools == nil || len(assistant.Tools) != 1 {
+			t.Errorf("expected a slice got %v", assistant.Tools)
+		}
+	})
+
+	t.Run("modify_assistant_empty_tools", func(t *testing.T) {
+		assistant, err := client.ModifyAssistant(ctx, assistantID, openai.AssistantRequest{
+			Name:         &assistantName,
+			Description:  &assistantDescription,
+			Model:        openai.GPT4TurboPreview,
+			Instructions: &assistantInstructions,
+			Tools:        make([]openai.AssistantTool, 0),
+		})
+
+		checks.NoError(t, err, "ModifyAssistant error")
+
+		if assistant.Tools == nil {
+			t.Errorf("expected a slice got %v", assistant.Tools)
+		}
+	})
 }
 
 func TestAzureAssistant(t *testing.T) {