Fixed flaky tests

The tests previously tested assertions against the replica after
executing changes in the source without waiting for the
replication to converge.

t/pt-table-sync/char_chunking.t

@@ -37,13 +37,7 @@ $sb->create_dbs($source_dbh, ['test']);
 $sb->load_file('source', "t/lib/samples/char-chunking/ascii.sql", "test");
 $source_dbh->do('alter table test.ascii drop column `i`');
 
-wait_until(
-   sub {
-      my $row;
-      eval {$row = $replica_dbh->selectall_arrayref("select * from test.ascii");};
-      return 1 if $row && @$row > 100;
-   },
-);
+$sb->wait_for_replicas();
 
 $replica_dbh->do('delete from test.ascii where c like "Zesus%"');
 

t/pt-table-sync/issue_218.t

@@ -40,6 +40,8 @@ $sb->wipe_clean($replica_dbh);
 $sb->create_dbs($source_dbh, [qw(issue218)]);
 $sb->use('source', '-e "CREATE TABLE issue218.t1 (i INT)"');
 $sb->use('source', '-e "INSERT INTO issue218.t1 VALUES (NULL)"');
+$sb->wait_for_replicas();
+
 qx($trunk/bin/pt-table-sync --no-check-replica --print --database issue218 h=127.1,P=12345,u=msandbox,p=msandbox P=12346);
 ok(!$?, 'Issue 218: NULL values compare as equal');
 

t/pt-table-sync/pt-1256.t

@@ -74,6 +74,8 @@ like(
    "PT-1256 Set the correct charset"
 );
 
+$sb->wait_for_replicas();
+
 SKIP: {
    my $vp = VersionParser->new($source_dbh);
    if ($vp->cmp('8.0') > -1 && $vp->cmp('8.0.14') < 0 && $vp->flavor() !~ m/maria/i) {
@@ -91,6 +93,8 @@ SKIP: {
     $output = `$trunk/bin/pt-table-sync --execute --lock-and-rename h=127.1,P=12345,u=msandbox,p=msandbox,D=test,t=t1 t=t2 2>&1`;
     $output = `/tmp/12345/use -e 'show create table test.t2'`;
     like($output, qr/COMMENT='test1'/, '--lock-and-rename worked');
+
+    $sb->wait_for_replicas();
 
     #4
     $row = $replica1_dbh->selectrow_hashref("SELECT f2 FROM test.t2 WHERE id = 1");