test: add test task delays and callbacks

Added test delays (iteration and full scan) and full scan
iteration callbacks.

Author: LeonidVas

test.lua

@@ -217,6 +217,17 @@ local function init_box()
         if_not_exists = true
     })
     truncate(f.id)
+
+    local g = box.schema.create_space('delays_test', {
+        engine = space_type,
+        if_not_exists = true
+    })
+    g:create_index('first', {
+        type = index_type,
+        parts = {1, 'NUM'},
+        if_not_exists = true
+    })
+    truncate(g.id)
 end
 
 local space_id = 'origin'
@@ -234,8 +245,9 @@ init_box()
 -- 6. default drop function test
 -- 7. restart test
 -- 8. complex key test
+-- 9. delays and scan callbacks test
 -- ========================================================================= --
-test:plan(8)
+test:plan(9)
 
 test:test('simple expires test',  function(test)
     test:plan(4)
@@ -540,4 +552,71 @@ test:test("complex key test", function(test)
     expirationd.kill_task("test")
 end)
 
+test:test('delays and scan callbacks test', function(test)
+    test:plan(4)
+
+    -- Prepare the space.
+    local tuples_count = 10
+    local time = fiber.time()
+    local space_name = 'delays_test'
+    local expire_delta = 10
+
+    for i = 1, tuples_count do
+        box.space[space_name]:insert{i, time + expire_delta}
+    end
+
+    -- To check all delays (iteration and full scan), two full scan
+    -- iterations will be performed.
+    local first_iteration_done = false
+    local task_name = 'delays_task'
+    local cond = fiber.cond()
+    local start_time = 0
+    local complete_time = 0
+
+    local iteration_delay = 1
+    local full_scan_delay = 2
+
+    expirationd.start(
+        task_name,
+        space_name,
+        check_tuple_expire_by_timestamp,
+        {
+            args = {
+                field_no = 2
+            },
+            tuples_per_iteration = 10,
+            iteration_delay = iteration_delay,
+            full_scan_delay = full_scan_delay,
+            on_full_scan_start = function(task)
+                start_time = fiber.time()
+                if first_iteration_done then
+                    -- Check the full scan delay with an accuracy
+                    -- of 0.1 seconds.
+                    test:ok(math.abs(start_time - complete_time -
+                        full_scan_delay) < 0.1, 'test full scan delay')
+                end
+            end,
+            on_full_scan_success = function(task)
+                -- Must be called twice.
+                test:ok(true, 'test success callback invoke')
+            end,
+            on_full_scan_complete = function(task)
+                complete_time = fiber.time()
+                if first_iteration_done then
+                    cond:signal()
+                else
+                    -- Check the iteration delay with an accuracy
+                    -- of 0.1 seconds.
+                    test:ok(math.abs(complete_time - start_time -
+                        iteration_delay) < 0.1, 'test iteration delay')
+                    first_iteration_done = true
+                end
+            end
+        }
+    )
+
+    cond:wait()
+    expirationd.kill_task(task_name)
+end)
+
 os.exit(test:check() and 0 or 1)