Verify userid after connecting to WebSocket

Listen for the 'whoyouare' reply to the 'whoami' request sent after the
WebSocket connects and log a warning if the userid does not match the
logged-in user for any reason.

src/sidebar/streamer.js

@@ -123,6 +123,11 @@ function Streamer($rootScope, annotationMapper, annotationUI, auth,
         handleAnnotationNotification(message);
       } else if (message.type === 'session-change') {
         handleSessionChangeNotification(message);
+      } else if (message.type === 'whoyouare') {
+        var userid = annotationUI.getState().session.userid;
+        if (message.userid !== userid) {
+          console.warn('WebSocket user ID "%s" does not match logged-in ID "%s"', message.userid, userid);
+        }
       } else {
         console.warn('received unsupported notification', message.type);
       }

src/sidebar/test/streamer-test.js

@@ -115,6 +115,11 @@ describe('Streamer', function () {
     fakeAnnotationUI = {
       annotationExists: sinon.stub().returns(false),
       isSidebar: sinon.stub().returns(true),
+      getState: sinon.stub().returns({
+        session: {
+          userid: 'jim@hypothes.is',
+        },
+      }),
     };
 
     fakeGroups = {
@@ -415,6 +420,60 @@ describe('Streamer', function () {
     });
   });
 
+  describe('whoyouare notifications', function () {
+    beforeEach(function () {
+      sinon.stub(console, 'warn');
+    });
+
+    afterEach(function () {
+      console.warn.restore();
+    });
+
+    unroll('does nothing if the userid matches the logged-in userid', function (testCase) {
+      fakeAnnotationUI.getState.returns({
+        session: {
+          userid: testCase.userid,
+        },
+      });
+      createDefaultStreamer();
+      return activeStreamer.connect().then(function () {
+        fakeWebSocket.notify({
+          type: 'whoyouare',
+          userid: testCase.websocketUserid,
+        });
+        assert.notCalled(console.warn);
+      });
+    }, [{
+      userid: 'acct:mr_bond@hypothes.is',
+      websocketUserid: 'acct:mr_bond@hypothes.is',
+    },{
+      userid: null,
+      websocketUserid: null,
+    }]);
+
+    unroll('logs a warning if the userid does not match the logged-in userid', function (testCase) {
+      fakeAnnotationUI.getState.returns({
+        session: {
+          userid: testCase.userid,
+        },
+      });
+      createDefaultStreamer();
+      return activeStreamer.connect().then(function () {
+        fakeWebSocket.notify({
+          type: 'whoyouare',
+          userid: testCase.websocketUserid,
+        });
+        assert.called(console.warn);
+      });
+    }, [{
+      userid: 'acct:mr_bond@hypothes.is',
+      websocketUserid: 'acct:the_spanish_inquisition@hypothes.is',
+    }, {
+      userid: null,
+      websocketUserid: 'acct:the_spanish_inquisition@hypothes.is',
+    }]);
+  });
+
   describe('reconnections', function () {
     it('resends configuration messages when a reconnection occurs', function () {
       createDefaultStreamer();