Fix flakiness due to create_room_synced (#702)

When we create a room, it's possible for a subsequent /sync to receive subset of
the intial events in that room. This was making some tests [1] flaky when
running in worker mode.

AFAICT there's nothing in the spec which forbids this behaviour. By way of a
workaround, we send a test message in the new room and wait for it to turn up
over /sync.

However, a corollary is that we can't rely on the /sync to contain all the
events in the room. Solution to that is to sync again in tests that actually
care about the sync body.

[1]: notably 'A message sent after an initial sync appears in the timeline of
an incremental sync.'

tests/10apidoc/30room-create.pl

@@ -161,11 +161,17 @@
    do => sub {
       my ( $user ) = @_;
 
+      my $room_id;
+
       matrix_create_room_synced(
          $user,
          room_version => '2',
       )->then( sub {
-         my ( $room_id, undef, $sync_body ) = @_;
+         ( $room_id ) = @_;
+
+         matrix_sync( $user );
+      })->then( sub {
+         my ( $sync_body ) = @_;
 
          log_if_fail "sync body", $sync_body;
 
@@ -188,7 +194,7 @@
    do => sub {
       my ( $user ) = @_;
 
-      matrix_create_room_synced(
+      matrix_create_room(
          $user,
          room_version => 1,
       )->main::expect_http_400()
@@ -207,7 +213,7 @@
    do => sub {
       my ( $user ) = @_;
 
-      matrix_create_room_synced(
+      matrix_create_room(
          $user,
          room_version => "agjkyhdsghkjackljkj",
       )->main::expect_http_400()
@@ -225,14 +231,20 @@
    do => sub {
       my ( $user ) = @_;
 
+      my $room_id;
+
       matrix_create_room_synced(
          $user,
          creation_content => {
             test => "azerty",
             room_version => "test",
          },
       )->then( sub {
-         my ( $room_id, undef, $sync_body ) = @_;
+         ( $room_id ) = @_;
+
+         matrix_sync( $user );
+      })->then( sub {
+         my ( $sync_body ) = @_;
 
          log_if_fail "sync body", $sync_body;
 
@@ -377,31 +389,45 @@ sub room_alias_fixture
 =head2 matrix_create_room_synced
 
     matrix_create_room_synced( $creator, %params )->then( sub {
-        my ( $room_id, $room_alias, $sync_body ) = @_;
+        my ( $room_id ) = @_;
     });
 
 Creates a new room, and waits for it to appear in the /sync response.
 
 The parameters are passed through to C<matrix_create_room>.
 
-The resultant future completes with three values: the room_id from the
-/createRoom response; the room_alias from the /createRoom response (which is
-non-standard and should not be relied upon); the /sync response.
+The resultant future completes with the room_id.
 
 =cut
 
 sub matrix_create_room_synced
 {
    my ( $user, %params ) = @_;
 
-   matrix_do_and_wait_for_sync( $user,
-      do => sub {
-         matrix_create_room( $user, %params );
-      },
-      check => sub {
-         my ( $sync_body, $room_id ) = @_;
-         return 0 if not exists $sync_body->{rooms}{join}{$room_id};
-         return $sync_body;
-      },
-   );
+   # we want to make sure we have all of the room-creation events before we return.
+   # The easiest way to do that is to send a sentinel message in the room and wait for
+   # that to turn up.
+   matrix_create_room( $user, %params )->then( sub {
+      my ( $room_id ) = @_;
+
+      matrix_do_and_wait_for_sync( $user,
+         do => sub {
+            my $uri = "/r0/rooms/$room_id/send/m.room.test";
+
+            do_request_json_for(
+               $user,
+               method => "POST",
+               uri    => $uri,
+               content => {},
+            );
+         },
+         check => sub {
+            my ( $sync_body, $send_body ) = @_;
+            my $event_id = $send_body->{event_id};
+            return sync_timeline_contains( $sync_body, $room_id, sub {
+               $_[0]->{event_id} eq $event_id
+            });
+         },
+      )->then_done( $room_id );
+   });
 }

tests/32room-versions.pl

@@ -8,11 +8,17 @@
       check => sub {
          my ( $user ) = @_;
 
+         my $room_id;
+
          matrix_create_room_synced(
             $user,
             room_version => $version,
          )->then( sub {
-            my ( $room_id, undef, $sync_body ) = @_;
+            ( $room_id ) = @_;
+
+            matrix_sync( $user );
+         })->then( sub {
+            my ( $sync_body ) = @_;
 
             log_if_fail "sync body", $sync_body;
 
@@ -42,14 +48,16 @@
          check => sub {
             my ( $user, $joiner, $room_alias_name ) = @_;
 
-            my ( $room_id, $room_alias, $event_id );
+            my ( $room_id, $event_id );
+
+            my $room_alias = sprintf( '#%s:%s', $room_alias_name, $user->server_name );
 
             matrix_create_room_synced(
                $user,
                room_version    => $version,
                room_alias_name => $room_alias_name,
             )->then( sub {
-               ( $room_id, $room_alias ) = @_;
+               ( $room_id ) = @_;
 
                matrix_join_room_synced( $joiner, $room_alias );
             })->then( sub {