test: use wait_cond to check follow status

After setting timeouts in `box.cfg` and before making a `replace` needs
to wait for replicas in `follow` status. Then if `wait_follow()` found
not `follow` status it returns true. Which immediately causes an error.

Fixes #3734
Part of #2436, #3232

test/replication/misc.result

@@ -146,15 +146,24 @@ test_run:cmd("setopt delimiter ';'")
 ---
 - true
 ...
+function wait_follow(replicaA, replicaB)
+    return test_run:wait_cond(function()
+        return replicaA.status ~= 'follow' or replicaB.status ~= 'follow'
+    end, 0.01)
+end ;
+---
+...
 function test_timeout()
+    local replicaA = box.info.replication[1].upstream or box.info.replication[2].upstream
+    local replicaB = box.info.replication[3].upstream or box.info.replication[2].upstream
+    local follows = test_run:wait_cond(function()
+        return replicaA.status == 'follow' or replicaB.status == 'follow'
+    end, 0.1)
+    if not follows then error('replicas not in follow status') end
     for i = 0, 99 do 
         box.space.test_timeout:replace({1})
-        fiber.sleep(0.005)
-        local rinfo = box.info.replication
-        if rinfo[1].upstream and rinfo[1].upstream.status ~= 'follow' or
-           rinfo[2].upstream and rinfo[2].upstream.status ~= 'follow' or
-           rinfo[3].upstream and rinfo[3].upstream.status ~= 'follow' then
-            return error('Replication broken')
+        if wait_follow(replicaA, replicaB) then
+            return error(box.info.replication)
         end
     end
     return true

test/replication/misc.test.lua

@@ -53,15 +53,22 @@ fiber=require('fiber')
 box.cfg{replication_timeout = 0.01, replication_connect_timeout=0.01}
 _ = box.schema.space.create('test_timeout'):create_index('pk')
 test_run:cmd("setopt delimiter ';'")
+function wait_follow(replicaA, replicaB)
+    return test_run:wait_cond(function()
+        return replicaA.status ~= 'follow' or replicaB.status ~= 'follow'
+    end, 0.01)
+end ;
 function test_timeout()
+    local replicaA = box.info.replication[1].upstream or box.info.replication[2].upstream
+    local replicaB = box.info.replication[3].upstream or box.info.replication[2].upstream
+    local follows = test_run:wait_cond(function()
+        return replicaA.status == 'follow' or replicaB.status == 'follow'
+    end, 0.1)
+    if not follows then error('replicas not in follow status') end
     for i = 0, 99 do 
         box.space.test_timeout:replace({1})
-        fiber.sleep(0.005)
-        local rinfo = box.info.replication
-        if rinfo[1].upstream and rinfo[1].upstream.status ~= 'follow' or
-           rinfo[2].upstream and rinfo[2].upstream.status ~= 'follow' or
-           rinfo[3].upstream and rinfo[3].upstream.status ~= 'follow' then
-            return error('Replication broken')
+        if wait_follow(replicaA, replicaB) then
+            return error(box.info.replication)
         end
     end
     return true