go-sdk/mcp/elicitation_test.go

// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"errors"
	"strings"
	"testing"
	"testing/synctest"

	"github.com/google/jsonschema-go/jsonschema"
	"github.com/modelcontextprotocol/go-sdk/internal/jsonrpc2"
	"github.com/modelcontextprotocol/go-sdk/jsonrpc"
)

// TODO: migrate other elicitation tests here.

func TestElicitationURLMode(t *testing.T) {
	ctx := context.Background()
	clientErr := errors.New("client failed to elicit")

	testCases := []struct {
		name             string
		handler          func(context.Context, *ElicitRequest) (*ElicitResult, error)
		params           *ElicitParams
		wantResultAction string
		wantErrMsg       string
		wantErrCode      int64
	}{
		{
			name: "success",
			handler: func(ctx context.Context, req *ElicitRequest) (*ElicitResult, error) {
				return &ElicitResult{Action: "accept"}, nil
			},
			params: &ElicitParams{
				Mode:    "url",
				Message: "Please provide information via URL",
				URL:     "https://example.com/form",
			},
			wantResultAction: "accept",
		},
		{
			name: "decline",
			handler: func(ctx context.Context, req *ElicitRequest) (*ElicitResult, error) {
				return &ElicitResult{Action: "decline"}, nil
			},
			params: &ElicitParams{
				Mode:    "url",
				Message: "Please provide information via URL",
				URL:     "https://example.com/form",
			},
			wantResultAction: "decline",
		},
		{
			name: "client error",
			handler: func(ctx context.Context, req *ElicitRequest) (*ElicitResult, error) {
				return nil, clientErr
			},
			params: &ElicitParams{
				Mode:    "url",
				Message: "This should fail",
				URL:     "https://example.com/form",
			},
			wantErrMsg: clientErr.Error(),
		},
		{
			name: "missing url",
			handler: func(ctx context.Context, req *ElicitRequest) (*ElicitResult, error) {
				return &ElicitResult{Action: "accept"}, nil
			},
			params: &ElicitParams{
				Mode:    "url",
				Message: "URL is missing",
			},
			wantErrMsg:  "URL must be set for URL elicitation",
			wantErrCode: jsonrpc.CodeInvalidParams,
		},
		{
			name: "schema not allowed",
			handler: func(ctx context.Context, req *ElicitRequest) (*ElicitResult, error) {
				return &ElicitResult{Action: "accept"}, nil
			},
			params: &ElicitParams{
				Mode:    "url",
				Message: "Schema is not allowed",
				URL:     "https://example.com/form",
				RequestedSchema: &jsonschema.Schema{
					Type: "object",
				},
			},
			wantErrMsg:  "requestedSchema must not be set for URL elicitation",
			wantErrCode: jsonrpc.CodeInvalidParams,
		},
	}
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			ct, st := NewInMemoryTransports()
			s := NewServer(testImpl, nil)
			ss, err := s.Connect(ctx, st, nil)
			if err != nil {
				t.Fatal(err)
			}
			defer ss.Close()

			c := NewClient(testImpl, &ClientOptions{
				Capabilities: &ClientCapabilities{
					Roots:   RootCapabilities{ListChanged: true},
					RootsV2: &RootCapabilities{ListChanged: true},
					Elicitation: &ElicitationCapabilities{
						URL: &URLElicitationCapabilities{},
					},
				},
				ElicitationHandler: tc.handler,
			})
			cs, err := c.Connect(ctx, ct, &ClientSessionOptions{ProtocolVersion: protocolVersion20251125})
			if err != nil {
				t.Fatal(err)
			}
			defer cs.Close()

			result, err := ss.Elicit(ctx, tc.params)

			if tc.wantErrMsg != "" {
				if err == nil || !strings.Contains(err.Error(), tc.wantErrMsg) {
					t.Fatalf("Elicit(...): got error %v, want containing %q", err, tc.wantErrMsg)
				}
				if tc.wantErrCode != 0 {
					if code := errorCode(err); code != tc.wantErrCode {
						t.Errorf("Elicit(...): got error code %d, want %d", code, tc.wantErrCode)
					}
				}
			} else {
				if err != nil {
					t.Fatalf("Elicit failed: %v", err)
				}
				if result.Action != tc.wantResultAction {
					t.Errorf("Elicit(...): got action %q, want %q", result.Action, tc.wantResultAction)
				}
			}
		})
	}
}

func TestElicitationCompleteNotification(t *testing.T) {
	synctest.Test(t, func(t *testing.T) {
		ctx := context.Background()

		var elicitationCompleteCh = make(chan *ElicitationCompleteParams, 1)

		c := NewClient(testImpl, &ClientOptions{
			Capabilities: &ClientCapabilities{
				Roots:   RootCapabilities{ListChanged: true},
				RootsV2: &RootCapabilities{ListChanged: true},
				Elicitation: &ElicitationCapabilities{
					URL: &URLElicitationCapabilities{},
				},
			},
			ElicitationHandler: func(context.Context, *ElicitRequest) (*ElicitResult, error) {
				return &ElicitResult{Action: "accept"}, nil
			},
			ElicitationCompleteHandler: func(_ context.Context, req *ElicitationCompleteNotificationRequest) {
				elicitationCompleteCh <- req.Params
			},
		})

		ct, st := NewInMemoryTransports()
		s := NewServer(testImpl, nil)
		ss, err := s.Connect(ctx, st, nil)
		if err != nil {
			t.Fatal(err)
		}
		defer ss.Close()
		cs, err := c.Connect(ctx, ct, &ClientSessionOptions{ProtocolVersion: protocolVersion20251125})
		if err != nil {
			t.Fatal(err)
		}
		defer cs.Close()

		// 1. Server initiates a URL elicitation
		elicitID := "testElicitationID-123"
		resp, err := ss.Elicit(ctx, &ElicitParams{
			Mode:          "url",
			Message:       "Please complete this form: ",
			URL:           "https://example.com/form?id=" + elicitID,
			ElicitationID: elicitID,
		})
		if err != nil {
			t.Fatalf("Elicit failed: %v", err)
		}
		if resp.Action != "accept" {
			t.Fatalf("Elicit action is %q, want %q", resp.Action, "accept")
		}

		// 2. Server sends elicitation complete notification (simulating out-of-band completion)
		err = ss.NotifyElicitationComplete(ctx, &ElicitationCompleteParams{
			ElicitationID: elicitID,
		})
		if err != nil {
			t.Fatalf("failed to send elicitation complete notification: %v", err)
		}

		// 3. Client should receive the notification
		gotParams := <-elicitationCompleteCh
		if gotParams.ElicitationID != elicitID {
			t.Errorf("elicitationComplete notification ID mismatch: got %q, want %q", gotParams.ElicitationID, elicitID)
		}
	})
}

func TestNotifyElicitationCompleteInvalidParams(t *testing.T) {
	ctx := context.Background()

	ct, st := NewInMemoryTransports()
	s := NewServer(testImpl, nil)
	ss, err := s.Connect(ctx, st, nil)
	if err != nil {
		t.Fatal(err)
	}
	defer ss.Close()
	c := NewClient(testImpl, nil)
	cs, err := c.Connect(ctx, ct, nil)
	if err != nil {
		t.Fatal(err)
	}
	defer cs.Close()

	// An empty elicitation ID cannot be matched to a pending elicitation by the
	// client, so it is rejected rather than sent.
	for _, tc := range []struct {
		name   string
		params *ElicitationCompleteParams
	}{
		{"nil params", nil},
		{"empty ID", &ElicitationCompleteParams{}},
	} {
		t.Run(tc.name, func(t *testing.T) {
			err := ss.NotifyElicitationComplete(ctx, tc.params)
			if !errors.Is(err, jsonrpc2.ErrInvalidParams) {
				t.Errorf("NotifyElicitationComplete(%v) = %v, want %v", tc.params, err, jsonrpc2.ErrInvalidParams)
			}
		})
	}
}

func TestElicitationNoValidationWithoutAccept(t *testing.T) {
	ctx := context.Background()

	schema := &jsonschema.Schema{
		Type: "object",
		Properties: map[string]*jsonschema.Schema{
			"test": {Type: "string"},
		},
		Required: []string{"test"},
	}

	testCases := []struct {
		name       string
		action     string
		content    map[string]any
		wantAction string
	}{
		{
			name:       "cancel action",
			action:     "cancel",
			content:    nil, // Empty content should be ignored
			wantAction: "cancel",
		},
		{
			name:       "decline action",
			action:     "decline",
			content:    map[string]any{}, // Empty content should be ignored
			wantAction: "decline",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			ct, st := NewInMemoryTransports()
			s := NewServer(testImpl, nil)
			ss, err := s.Connect(ctx, st, nil)
			if err != nil {
				t.Fatal(err)
			}
			defer ss.Close()

			c := NewClient(testImpl, &ClientOptions{
				ElicitationHandler: func(context.Context, *ElicitRequest) (*ElicitResult, error) {
					return &ElicitResult{Action: tc.action, Content: tc.content}, nil
				},
			})
			cs, err := c.Connect(ctx, ct, &ClientSessionOptions{ProtocolVersion: protocolVersion20251125})
			if err != nil {
				t.Fatal(err)
			}
			defer cs.Close()

			res, err := ss.Elicit(ctx, &ElicitParams{
				Message:         "Test bug",
				RequestedSchema: schema,
			})

			if err != nil {
				t.Fatalf("Elicit failed: %v", err)
			}

			if res.Action != tc.wantAction {
				t.Errorf("Expected action %q, got %q", tc.wantAction, res.Action)
			}
		})
	}
}