test: fix flakiness of replication/qsync_basic

The async transactions should always wait for LSN from the master after
switch to replica.

Closes tarantool/tarantool-qa#274

NO_CHANGELOG=testing
NO_DOC=testing

test/replication/qsync_basic.result

@@ -162,10 +162,13 @@ box.space.sync:select{}
  | ...
 
 -- Check consistency on replica.
-test_run:cmd('switch replica')
+test_run:switch('replica')
  | ---
  | - true
  | ...
+test_run:wait_lsn('replica', 'default')
+ | ---
+ | ...
 box.space.sync:select{}
  | ---
  | - - [1]
@@ -256,6 +259,9 @@ test_run:switch('replica')
  | ---
  | - true
  | ...
+test_run:wait_lsn('replica', 'default')
+ | ---
+ | ...
 box.space.test:select{5}
  | ---
  | - - [5]
@@ -293,6 +299,9 @@ test_run:switch('replica')
  | ---
  | - true
  | ...
+test_run:wait_lsn('replica', 'default')
+ | ---
+ | ...
 box.space.test:select{6}
  | ---
  | - []
@@ -355,6 +364,9 @@ test_run:switch('replica')
  | ---
  | - true
  | ...
+test_run:wait_lsn('replica', 'default')
+ | ---
+ | ...
 box.space.sync:select{8}
  | ---
  | - - [8]
@@ -409,6 +421,9 @@ test_run:switch('replica')
  | ---
  | - true
  | ...
+test_run:wait_lsn('replica', 'default')
+ | ---
+ | ...
 box.space.sync:select{9}
  | ---
  | - []
@@ -459,6 +474,9 @@ test_run:switch('replica')
  | ---
  | - true
  | ...
+test_run:wait_lsn('replica', 'default')
+ | ---
+ | ...
 box.space.sync:select{10}
  | ---
  | - - [10]
@@ -496,6 +514,9 @@ test_run:switch('replica')
  | ---
  | - true
  | ...
+test_run:wait_lsn('replica', 'default')
+ | ---
+ | ...
 box.space.sync:select{7}
  | ---
  | - - [7]
@@ -544,6 +565,9 @@ test_run:switch('replica')
  | ---
  | - true
  | ...
+test_run:wait_lsn('replica', 'default')
+ | ---
+ | ...
 box.space.sync:select{11}
  | ---
  | - []

test/replication/qsync_basic.test.lua

@@ -65,7 +65,8 @@ box.space.sync:insert{3}
 box.space.sync:select{}
 
 -- Check consistency on replica.
-test_run:cmd('switch replica')
+test_run:switch('replica')
+test_run:wait_lsn('replica', 'default')
 box.space.sync:select{}
 
 -- Check consistency in recovered data.
@@ -105,6 +106,7 @@ f:status()
 s:select{5}
 box.space.sync:select{5}
 test_run:switch('replica')
+test_run:wait_lsn('replica', 'default')
 box.space.test:select{5}
 box.space.sync:select{5}
 -- Ensure sync rollback will affect all pending async transactions
@@ -116,6 +118,7 @@ f:status()
 s:select{6}
 box.space.sync:select{6}
 test_run:switch('replica')
+test_run:wait_lsn('replica', 'default')
 box.space.test:select{6}
 box.space.sync:select{6}
 
@@ -141,6 +144,7 @@ box.space.locallocal:select{8}
 box.space.test:select{8}
 
 test_run:switch('replica')
+test_run:wait_lsn('replica', 'default')
 box.space.sync:select{8}
 box.space.locallocal:select{8}
 box.space.test:select{8}
@@ -160,6 +164,7 @@ box.space.sync:select{9}
 box.space.locallocal:select{9}
 box.space.test:select{9}
 test_run:switch('replica')
+test_run:wait_lsn('replica', 'default')
 box.space.sync:select{9}
 box.space.locallocal:select{9}
 box.space.test:select{9}
@@ -183,6 +188,7 @@ box.space.sync:select{10}
 box.space.locallocal:select{10}
 
 test_run:switch('replica')
+test_run:wait_lsn('replica', 'default')
 box.space.sync:select{10}
 box.space.locallocal:select{10}
 
@@ -196,6 +202,7 @@ box.space.sync:replace{7}
 newlsn = box.info.lsn
 assert(newlsn >= oldlsn + 2)
 test_run:switch('replica')
+test_run:wait_lsn('replica', 'default')
 box.space.sync:select{7}
 
 --
@@ -214,6 +221,7 @@ test_run:wait_cond(function() return f:status() == 'dead' end)
 ok, err
 box.space.sync:select{11}
 test_run:switch('replica')
+test_run:wait_lsn('replica', 'default')
 box.space.sync:select{11}
 
 -- Test it is possible to early ACK a transaction with a new quorum.