test: helpers.retry()

test/functional/helpers.lua

@@ -243,6 +243,19 @@ local function connect(file_or_address)
   return Session.new(stream)
 end
 
+-- Calls fn() until it returns without error, up to `max` times.
+local function retry(fn, max)
+  local retries = max and (max - 1) or 2
+  for _ = 1, retries do
+    local success = pcall(fn)
+    if success then
+      return
+    end
+  end
+  -- pcall() is not used for the final attempt so failure can bubble up.
+  fn()
+end
+
 local function clear(...)
   local args = {unpack(nvim_argv)}
   local new_args
@@ -530,6 +543,7 @@ return function(after_each)
     prepend_argv = prepend_argv,
     clear = clear,
     connect = connect,
+    retry = retry,
     spawn = spawn,
     dedent = dedent,
     source = source,

test/functional/legacy/061_undo_tree_spec.lua

@@ -98,15 +98,7 @@ describe('undo tree:', function()
         expect_line('123456abc')
       end
 
-      -- Retry up to 3 times. pcall() is _not_ used for the final attempt, so
-      -- that failure messages can bubble up.
-      for _ = 1, 2 do
-        local success = pcall(test_earlier_later)
-        if success then
-          return
-        end
-      end
-      test_earlier_later()
+      helpers.retry(test_earlier_later)
     end)
 
     it('file-write specifications', function()