package server
import (
"bytes"
"encoding/json"
"reflect"
"testing"
"github.com/modelcontextprotocol/go-sdk/mcp"
)
// recursively scan a value for *mcp.Prompt pointers
func collectPrompts(v reflect.Value, seen map[uintptr]bool) []*mcp.Prompt {
var out []*mcp.Prompt
if !v.IsValid() {
return out
}
// unwrap pointers and interfaces
for v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface {
if v.IsNil() {
return out
}
ptr := v.Pointer()
if seen[ptr] {
return out
}
seen[ptr] = true
v = v.Elem()
}
switch v.Kind() {
case reflect.Struct:
// If this is an mcp.Prompt value
if v.Type() == reflect.TypeOf(mcp.Prompt{}) {
if v.CanAddr() {
p := v.Addr().Interface().(*mcp.Prompt)
out = append(out, p)
}
return out
}
// scan exported fields only to avoid panics on unexported field Interface()
for i := 0; i < v.NumField(); i++ {
f := v.Field(i)
if !f.IsValid() {
continue
}
// skip unexported fields we cannot Interface
if !f.CanInterface() {
continue
}
out = append(out, collectPrompts(f, seen)...)
}
case reflect.Slice, reflect.Array:
for i := 0; i < v.Len(); i++ {
out = append(out, collectPrompts(v.Index(i), seen)...)
}
case reflect.Map:
for _, k := range v.MapKeys() {
out = append(out, collectPrompts(v.MapIndex(k), seen)...)
}
}
return out
}
func TestPromptsHaveNoNullSlices(t *testing.T) {
// Create a server instance and register prompts
srv := mcp.NewServer(&mcp.Implementation{Name: "test", Version: "v0"}, nil)
s := &MCPServer{server: srv, db: nil}
s.setupPrompts()
// use RegisteredPrompts cache populated by safeAddPrompt
prompts := s.RegisteredPrompts
if len(prompts) == 0 {
t.Fatalf("no prompts registered via safeAddPrompt")
}
for _, p := range prompts {
b, err := json.Marshal(p)
if err != nil {
t.Fatalf("failed to marshal prompt %v: %v", p, err)
}
if bytes.Contains(b, []byte(": null")) {
t.Errorf("prompt %q JSON contains null slice: %s", p.Name, string(b))
}
}
}
