chore: Add distant federation server mock (#7115)

Encapsulates the federation server counterpart & makes the test more configurable.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7115
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: Michael Jerger <michael.jerger@meissa-gmbh.de>
Co-committed-by: Michael Jerger <michael.jerger@meissa-gmbh.de>

modules/test/distant_federation_server_mock.go

@@ -0,0 +1,117 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package test
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+type FederationServerMockPerson struct {
+	ID     int64
+	Name   string
+	PubKey string
+}
+type FederationServerMockRepository struct {
+	ID int64
+}
+type FederationServerMock struct {
+	Persons      []FederationServerMockPerson
+	Repositories []FederationServerMockRepository
+	LastPost     string
+}
+
+func NewFederationServerMockPerson(id int64, name string) FederationServerMockPerson {
+	return FederationServerMockPerson{
+		ID:   id,
+		Name: name,
+		PubKey: `"-----BEGIN PUBLIC KEY-----\nMIIBojANBgkqhkiG9w0BAQEFAAOCAY8AMIIBigKCAYEA18H5s7N6ItZUAh9tneII\nIuZdTTa3cZlLa/9ejWAHTkcp3WLW+/zbsumlMrWYfBy2/yTm56qasWt38iY4D6ul\n` +
+			`CPiwhAqX3REvVq8tM79a2CEqZn9ka6vuXoDgBg/sBf/BUWqf7orkjUXwk/U0Egjf\nk5jcurF4vqf1u+rlAHH37dvSBaDjNj6Qnj4OP12bjfaY/yvs7+jue/eNXFHjzN4E\n` +
+			`T2H4B/yeKTJ4UuAwTlLaNbZJul2baLlHelJPAsxiYaziVuV5P+IGWckY6RSerRaZ\nAkc4mmGGtjAyfN9aewe+lNVfwS7ElFx546PlLgdQgjmeSwLX8FWxbPE5A/PmaXCs\n` +
+			`nx+nou+3dD7NluULLtdd7K+2x02trObKXCAzmi5/Dc+yKTzpFqEz+hLNCz7TImP/\ncK//NV9Q+X67J9O27baH9R9ZF4zMw8rv2Pg0WLSw1z7lLXwlgIsDapeMCsrxkVO4\n` +
+			`LXX5AQ1xQNtlssnVoUBqBrvZsX2jUUKUocvZqMGuE4hfAgMBAAE=\n-----END PUBLIC KEY-----\n"`,
+	}
+}
+
+func NewFederationServerMockRepository(id int64) FederationServerMockRepository {
+	return FederationServerMockRepository{
+		ID: id,
+	}
+}
+
+func (p FederationServerMockPerson) marshal(host string) string {
+	return fmt.Sprintf(`{"@context":["https://www.w3.org/ns/activitystreams","https://w3id.org/security/v1"],`+
+		`"id":"http://%[1]v/api/activitypub/user-id/%[2]v",`+
+		`"type":"Person",`+
+		`"icon":{"type":"Image","mediaType":"image/png","url":"http://%[1]v/avatars/1bb05d9a5f6675ed0272af9ea193063c"},`+
+		`"url":"http://%[1]v/%[2]v",`+
+		`"inbox":"http://%[1]v/api/activitypub/user-id/%[2]v/inbox",`+
+		`"outbox":"http://%[1]v/api/activitypub/user-id/%[2]v/outbox",`+
+		`"preferredUsername":"%[3]v",`+
+		`"publicKey":{"id":"http://%[1]v/api/activitypub/user-id/%[2]v#main-key",`+
+		`"owner":"http://%[1]v/api/activitypub/user-id/%[2]v",`+
+		`"publicKeyPem":%[4]v}}`, host, p.ID, p.Name, p.PubKey)
+}
+
+func NewFederationServerMock() *FederationServerMock {
+	return &FederationServerMock{
+		Persons: []FederationServerMockPerson{
+			NewFederationServerMockPerson(15, "stargoose1"),
+			NewFederationServerMockPerson(30, "stargoose2"),
+		},
+		Repositories: []FederationServerMockRepository{
+			NewFederationServerMockRepository(1),
+		},
+		LastPost: "",
+	}
+}
+
+func (mock *FederationServerMock) DistantServer(t *testing.T) *httptest.Server {
+	federatedRoutes := http.NewServeMux()
+	federatedRoutes.HandleFunc("/.well-known/nodeinfo",
+		func(res http.ResponseWriter, req *http.Request) {
+			// curl -H "Accept: application/json" https://federated-repo.prod.meissa.de/.well-known/nodeinfo
+			// TODO: as soon as content-type will become important:  content-type: application/json;charset=utf-8
+			fmt.Fprintf(res, `{"links":[{"href":"http://%s/api/v1/nodeinfo","rel":"http://nodeinfo.diaspora.software/ns/schema/2.1"}]}`, req.Host)
+		})
+	federatedRoutes.HandleFunc("/api/v1/nodeinfo",
+		func(res http.ResponseWriter, req *http.Request) {
+			// curl -H "Accept: application/json" https://federated-repo.prod.meissa.de/api/v1/nodeinfo
+			fmt.Fprint(res, `{"version":"2.1","software":{"name":"forgejo","version":"1.20.0+dev-3183-g976d79044",`+
+				`"repository":"https://codeberg.org/forgejo/forgejo.git","homepage":"https://forgejo.org/"},`+
+				`"protocols":["activitypub"],"services":{"inbound":[],"outbound":["rss2.0"]},`+
+				`"openRegistrations":true,"usage":{"users":{"total":14,"activeHalfyear":2}},"metadata":{}}`)
+		})
+	for _, person := range mock.Persons {
+		federatedRoutes.HandleFunc(fmt.Sprintf("/api/v1/activitypub/user-id/%v", person.ID),
+			func(res http.ResponseWriter, req *http.Request) {
+				// curl -H "Accept: application/json" https://federated-repo.prod.meissa.de/api/v1/activitypub/user-id/2
+				fmt.Fprint(res, person.marshal(req.Host))
+			})
+	}
+	for _, repository := range mock.Repositories {
+		federatedRoutes.HandleFunc(fmt.Sprintf("/api/v1/activitypub/repository-id/%v/inbox/", repository.ID),
+			func(res http.ResponseWriter, req *http.Request) {
+				if req.Method != "POST" {
+					t.Errorf("POST expected at: %q", req.URL.EscapedPath())
+				}
+				buf := new(strings.Builder)
+				_, err := io.Copy(buf, req.Body)
+				if err != nil {
+					t.Errorf("Error reading body: %q", err)
+				}
+				mock.LastPost = buf.String()
+			})
+	}
+	federatedRoutes.HandleFunc("/",
+		func(res http.ResponseWriter, req *http.Request) {
+			t.Errorf("Unhandled request: %q", req.URL.EscapedPath())
+		})
+	federatedSrv := httptest.NewServer(federatedRoutes)
+	return federatedSrv
+}