// 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_test
import (
"encoding/json"
"fmt"
"testing"
"github.com/google/go-cmp/cmp"
"github.com/modelcontextprotocol/go-sdk/mcp"
)
func TestContent(t *testing.T) {
tests := []struct {
in mcp.Content
want string // json serialization
}{
{
&mcp.TextContent{Text: "hello"},
`{"type":"text","text":"hello"}`,
},
{
&mcp.TextContent{Text: ""},
`{"type":"text","text":""}`,
},
{
&mcp.TextContent{},
`{"type":"text","text":""}`,
},
{
&mcp.TextContent{
Text: "hello",
Meta: mcp.Meta{"key": "value"},
Annotations: &mcp.Annotations{Priority: 1.0},
},
`{"type":"text","text":"hello","_meta":{"key":"value"},"annotations":{"priority":1}}`,
},
{
&mcp.ImageContent{
Data: []byte("a1b2c3"),
MIMEType: "image/png",
},
`{"type":"image","mimeType":"image/png","data":"YTFiMmMz"}`,
},
{
&mcp.ImageContent{MIMEType: "image/png", Data: []byte{}},
`{"type":"image","mimeType":"image/png","data":""}`,
},
{
&mcp.ImageContent{Data: []byte("test")},
`{"type":"image","mimeType":"","data":"dGVzdA=="}`,
},
{
&mcp.ImageContent{
Data: []byte("a1b2c3"),
MIMEType: "image/png",
Meta: mcp.Meta{"key": "value"},
Annotations: &mcp.Annotations{Priority: 1.0},
},
`{"type":"image","mimeType":"image/png","data":"YTFiMmMz","_meta":{"key":"value"},"annotations":{"priority":1}}`,
},
{
&mcp.AudioContent{
Data: []byte("a1b2c3"),
MIMEType: "audio/wav",
},
`{"type":"audio","mimeType":"audio/wav","data":"YTFiMmMz"}`,
},
{
&mcp.AudioContent{MIMEType: "audio/wav", Data: []byte{}},
`{"type":"audio","mimeType":"audio/wav","data":""}`,
},
{
&mcp.AudioContent{Data: []byte("test")},
`{"type":"audio","mimeType":"","data":"dGVzdA=="}`,
},
{
&mcp.AudioContent{
Data: []byte("a1b2c3"),
MIMEType: "audio/wav",
Meta: mcp.Meta{"key": "value"},
Annotations: &mcp.Annotations{Priority: 1.0},
},
`{"type":"audio","mimeType":"audio/wav","data":"YTFiMmMz","_meta":{"key":"value"},"annotations":{"priority":1}}`,
},
{
&mcp.EmbeddedResource{
Resource: &mcp.ResourceContents{URI: "file://foo", MIMEType: "text", Text: "abc"},
},
`{"type":"resource","resource":{"uri":"file://foo","mimeType":"text","text":"abc"}}`,
},
{
&mcp.EmbeddedResource{
Resource: &mcp.ResourceContents{URI: "file://foo", MIMEType: "image/png", Blob: []byte("a1b2c3")},
},
`{"type":"resource","resource":{"uri":"file://foo","mimeType":"image/png","blob":"YTFiMmMz"}}`,
},
{
&mcp.EmbeddedResource{
Resource: &mcp.ResourceContents{URI: "file://foo", MIMEType: "text", Text: "abc"},
Meta: mcp.Meta{"key": "value"},
Annotations: &mcp.Annotations{Priority: 1.0},
},
`{"type":"resource","resource":{"uri":"file://foo","mimeType":"text","text":"abc"},"_meta":{"key":"value"},"annotations":{"priority":1}}`,
},
{
&mcp.ResourceLink{
URI: "file:///path/to/file.txt",
Name: "file.txt",
},
`{"type":"resource_link","uri":"file:///path/to/file.txt","name":"file.txt"}`,
},
{
&mcp.ResourceLink{
URI: "https://example.com/resource",
Name: "Example Resource",
Title: "A comprehensive example resource",
Description: "This resource demonstrates all fields",
MIMEType: "text/plain",
Meta: mcp.Meta{"custom": "metadata"},
Icons: []mcp.Icon{{Source: "foobar", MIMEType: "image/png", Sizes: []string{"48x48"}, Theme: mcp.IconThemeLight}},
},
`{"type":"resource_link","mimeType":"text/plain","uri":"https://example.com/resource","name":"Example Resource","title":"A comprehensive example resource","description":"This resource demonstrates all fields","_meta":{"custom":"metadata"},"icons":[{"src":"foobar","mimeType":"image/png","sizes":["48x48"],"theme":"light"}]}`,
},
}
for _, test := range tests {
got, err := json.Marshal(test.in)
if err != nil {
t.Fatal(err)
}
if diff := cmp.Diff(test.want, string(got)); diff != "" {
t.Errorf("json.Marshal(%v) mismatch (-want +got):\n%s", test.in, diff)
}
result := fmt.Sprintf(`{"content":[%s]}`, string(got))
var out mcp.CallToolResult
if err := json.Unmarshal([]byte(result), &out); err != nil {
t.Fatal(err)
}
if diff := cmp.Diff(test.in, out.Content[0]); diff != "" {
t.Errorf("json.Unmarshal(%q) mismatch (-want +got):\n%s", string(got), diff)
}
}
}
func TestEmbeddedResource(t *testing.T) {
for _, tt := range []struct {
rc *mcp.ResourceContents
want string // marshaled JSON
}{
{
&mcp.ResourceContents{URI: "u", Text: "t"},
`{"uri":"u","text":"t"}`,
},
{
&mcp.ResourceContents{URI: "u", MIMEType: "m", Text: "t", Meta: mcp.Meta{"key": "value"}},
`{"uri":"u","mimeType":"m","text":"t","_meta":{"key":"value"}}`,
},
{
&mcp.ResourceContents{URI: "u"},
`{"uri":"u"}`,
},
{
&mcp.ResourceContents{URI: "u", Blob: []byte{}},
`{"uri":"u","blob":""}`,
},
{
&mcp.ResourceContents{URI: "u", Blob: []byte{1}},
`{"uri":"u","blob":"AQ=="}`,
},
{
&mcp.ResourceContents{URI: "u", MIMEType: "m", Blob: []byte{1}, Meta: mcp.Meta{"key": "value"}},
`{"uri":"u","mimeType":"m","blob":"AQ==","_meta":{"key":"value"}}`,
},
} {
data, err := json.Marshal(tt.rc)
if err != nil {
t.Fatal(err)
}
if got := string(data); got != tt.want {
t.Errorf("%#v:\ngot %s\nwant %s", tt.rc, got, tt.want)
}
urc := new(mcp.ResourceContents)
if err := json.Unmarshal(data, urc); err != nil {
t.Fatal(err)
}
// Since Blob is omitempty, the empty slice changes to nil.
if diff := cmp.Diff(tt.rc, urc); diff != "" {
t.Errorf("mismatch (-want, +got):\n%s", diff)
}
}
}
// TestContentUnmarshal tests that unmarshaling JSON into various Content types
// works correctly, including when the Content fields are initially nil.
func TestContentUnmarshal(t *testing.T) {
valInt64 := int64(24)
tests := []struct {
name string
json string
content mcp.Content
expectContent mcp.Content
}{
{
name: "ResourceLink",
json: `{"type":"resource_link","mimeType":"text/plain","uri":"https://example.com/resource","name":"Example Resource","title":"A comprehensive example resource","description":"This resource demonstrates all fields","_meta":{"custom":"metadata"},"icons":[{"src":"foobar","mimeType":"image/png","sizes":["48x48"],"theme":"light"}], "size":24,"annotations":{"audience":["user","assistant"],"lastModified":"2025-01-12T15:00:58Z","priority":0.5}}`,
content: &mcp.ResourceLink{},
expectContent: &mcp.ResourceLink{
URI: "https://example.com/resource",
Name: "Example Resource",
Title: "A comprehensive example resource",
Description: "This resource demonstrates all fields",
MIMEType: "text/plain",
// Meta: mcp.Meta{"custom": "metadata"},
Size: &valInt64,
Annotations: &mcp.Annotations{Audience: []mcp.Role{"user", "assistant"}, LastModified: "2025-01-12T15:00:58Z", Priority: 0.5},
Icons: []mcp.Icon{{Source: "foobar", MIMEType: "image/png", Sizes: []string{"48x48"}, Theme: mcp.IconThemeLight}},
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
// Test that unmarshaling doesn't panic on nil Content fields
defer func() {
if r := recover(); r != nil {
t.Errorf("UnmarshalJSON panicked: %v", r)
}
}()
err := json.Unmarshal([]byte(tt.json), tt.content)
if err != nil {
t.Errorf("UnmarshalJSON failed: %v", err)
}
// Verify that the Content field was properly populated
if cmp.Diff(tt.expectContent, tt.content) != "" {
t.Errorf("Content is not equal: %v", cmp.Diff(tt.expectContent, tt.content))
}
})
}
}