Add support for FEP-2c59 (#38239)

spec/services/activitypub/fetch_remote_actor_service_spec.rb

@@ -133,5 +133,97 @@ RSpec.describe ActivityPub::FetchRemoteActorService do
         expect(subject.call('https://fake.address/@foo', prefetched_body: actor.to_json)).to be_nil
       end
     end
+
+    context 'when the actor uses the webfinger propery from FEP-2c59' do
+      before do
+        actor[:webfinger] = acct
+      end
+
+      context 'when URI and WebFinger share the same host' do
+        let(:acct) { 'alice@example.com' }
+        let!(:webfinger) { { subject: "acct:#{acct}", links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/activity+json' }] } }
+
+        before do
+          stub_request(:get, 'https://example.com/alice').to_return(body: actor.to_json, headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, "https://example.com/.well-known/webfinger?resource=acct:#{acct}").to_return(body: webfinger.to_json, headers: { 'Content-Type': 'application/jrd+json' })
+        end
+
+        it 'fetches resource and looks up webfinger and sets values' do
+          account
+
+          expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+          expect(a_request(:get, "https://example.com/.well-known/webfinger?resource=acct:#{acct}")).to have_been_made.once
+
+          expect(account.username).to eq 'alice'
+          expect(account.domain).to eq 'example.com'
+        end
+
+        it_behaves_like 'sets profile data'
+      end
+
+      context 'when WebFinger returns a different URI' do
+        let(:acct) { 'alice@example.com' }
+        let!(:webfinger) { { subject: "acct:#{acct}", links: [{ rel: 'self', href: 'https://example.com/bob', type: 'application/activity+json' }] } }
+
+        before do
+          stub_request(:get, 'https://example.com/alice').to_return(body: actor.to_json, headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, "https://example.com/.well-known/webfinger?resource=acct:#{acct}").to_return(body: webfinger.to_json, headers: { 'Content-Type': 'application/jrd+json' })
+        end
+
+        it 'fetches resource and looks up webfinger and does not create account' do
+          expect(account).to be_nil
+
+          expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+          expect(a_request(:get, "https://example.com/.well-known/webfinger?resource=acct:#{acct}")).to have_been_made.once
+        end
+      end
+
+      context 'when WebFinger is at another domain' do
+        let(:acct) { 'alice@iscool.af' }
+        let!(:webfinger) { { subject: "acct:#{acct}", links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/activity+json' }] } }
+
+        before do
+          stub_request(:get, 'https://example.com/alice').to_return(body: actor.to_json, headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, "https://iscool.af/.well-known/webfinger?resource=acct:#{acct}").to_return(body: webfinger.to_json, headers: { 'Content-Type': 'application/jrd+json' })
+        end
+
+        it 'fetches resource and looks up webfinger and follows redirect and sets values' do
+          account
+
+          expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+          expect(a_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com')).to_not have_been_made
+          expect(a_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af')).to have_been_made.once
+
+          expect(account.username).to eq 'alice'
+          expect(account.domain).to eq 'iscool.af'
+        end
+
+        it_behaves_like 'sets profile data'
+      end
+
+      context 'when WebFinger is at another domain and redirects back' do
+        let(:acct) { 'alice@iscool.af' }
+        let!(:webfinger) { { subject: 'acct:alice@example.com', links: [{ rel: 'self', href: 'https://example.com/alice', type: 'application/activity+json' }] } }
+
+        before do
+          stub_request(:get, 'https://example.com/alice').to_return(body: actor.to_json, headers: { 'Content-Type': 'application/activity+json' })
+          stub_request(:get, "https://iscool.af/.well-known/webfinger?resource=acct:#{acct}").to_return(body: webfinger.to_json, headers: { 'Content-Type': 'application/jrd+json' })
+          stub_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com').to_return(body: webfinger.to_json, headers: { 'Content-Type': 'application/jrd+json' })
+        end
+
+        it 'fetches resource and looks up webfinger and follows redirect and sets values' do
+          account
+
+          expect(a_request(:get, 'https://example.com/alice')).to have_been_made.once
+          expect(a_request(:get, 'https://iscool.af/.well-known/webfinger?resource=acct:alice@iscool.af')).to have_been_made.once
+          expect(a_request(:get, 'https://example.com/.well-known/webfinger?resource=acct:alice@example.com')).to have_been_made
+
+          expect(account.username).to eq 'alice'
+          expect(account.domain).to eq 'example.com'
+        end
+
+        it_behaves_like 'sets profile data'
+      end
+    end
   end
 end