summercms/modules/pier/prompt_ceiling_test.go

package pier_test

import (
	"context"
	"errors"
	"slices"
	"strings"
	"testing"
	"time"

	"git.golem15.com/golem15/summercms/modules/pact"
	"github.com/modelcontextprotocol/go-sdk/mcp"
)

// promptNames lists the prompt names a session sees, sorted.
func promptNames(t *testing.T, ctx context.Context, cs *mcp.ClientSession) []string {
	t.Helper()
	list, err := cs.ListPrompts(ctx, nil)
	if err != nil {
		t.Fatalf("prompts/list: %v", err)
	}
	var out []string
	for _, p := range list.Prompts {
		out = append(out, p.Name)
	}
	slices.Sort(out)
	return out
}

// TestPromptWriteCeiling pins plan 06's prompt ceiling (C-IN-01, P-28): a
// prompt declaring Writes is listed for a read and write grant and hidden
// from a read-only grant (and cannot be fetched by it), while a prompt
// without Writes is listed for both.
func TestPromptWriteCeiling(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	draft := summarizePrompt()
	draft.Name = "draft"
	draft.Writes = true
	in := startInstance(t, newApp(t, appSpec{guards: []pact.MCPGuard{&acmeGuard{}}}),
		acmePlugin{tools: []pact.MCPTool{echoTool()}, prompts: []pact.MCPPrompt{summarizePrompt(), draft}})
	t.Cleanup(in.pier().StopReaper)

	for _, c := range []struct {
		name  string
		token string
		want  []string
	}{
		{"read and write grant", "oas_at_test", []string{"acme_draft", "acme_summarize"}},
		{"read-only grant", "oas_at_read", []string{"acme_summarize"}},
	} {
		t.Run(c.name, func(t *testing.T) {
			for _, version := range []string{"", "newest"} {
				cs := sdkClient(t, ctx, in.url(), c.token, clientOpts{version: version})
				if got := promptNames(t, ctx, cs); !slices.Equal(got, c.want) {
					t.Fatalf("version %q: prompts = %v, want %v", version, got, c.want)
				}
				_, err := cs.GetPrompt(ctx, &mcp.GetPromptParams{Name: "acme_draft", Arguments: map[string]string{"topic": "x"}})
				if allowed := slices.Contains(c.want, "acme_draft"); (err == nil) != allowed {
					t.Fatalf("version %q: get acme_draft err = %v, allowed %v", version, err, allowed)
				}
			}
		})
	}
}

// TestPromptRenderError pins RA-WR-05: a prompt whose Render fails answers a
// fixed JSON-RPC error on both paths; the cause (here a database error
// naming its host and user) is logged server-side and never reaches the
// client.
func TestPromptRenderError(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	const cause = `failed to connect to host=db.internal user=summer database=app: dial tcp 10.0.0.5:5432`
	broken := summarizePrompt()
	broken.Name = "broken"
	broken.Render = func(context.Context, map[string]string) ([]pact.MCPPromptMessage, error) {
		return nil, errors.New(cause)
	}
	in := startInstance(t, newApp(t, appSpec{guards: []pact.MCPGuard{&acmeGuard{}}}),
		acmePlugin{tools: []pact.MCPTool{echoTool()}, prompts: []pact.MCPPrompt{broken}})
	t.Cleanup(in.pier().StopReaper)
	logs := captureLogs(t)

	for _, version := range []string{"", "newest"} {
		cs := sdkClient(t, ctx, in.url(), "oas_at_test", clientOpts{version: version})
		_, err := cs.GetPrompt(ctx, &mcp.GetPromptParams{Name: "acme_broken", Arguments: map[string]string{"topic": "x"}})
		if err == nil {
			t.Fatalf("version %q: a failing Render answered no error", version)
		}
		if strings.Contains(err.Error(), "db.internal") || strings.Contains(err.Error(), "10.0.0.5") {
			t.Fatalf("version %q: the Render cause reached the client: %v", version, err)
		}
		if !strings.Contains(err.Error(), "pier: the prompt could not be rendered") {
			t.Fatalf("version %q: error = %v, want the fixed text", version, err)
		}
	}
	if !strings.Contains(logs.String(), "db.internal") {
		t.Fatalf("the Render cause was not logged: %s", logs.String())
	}
}