test: add tests for expirationd.stats()

Closes #77

test/unit/expirationd_stats_test.lua

@@ -0,0 +1,84 @@
+local expirationd = require("expirationd")
+local fiber = require("fiber")
+local t = require("luatest")
+local g = t.group("stats")
+
+local helpers = require("test.helper")
+
+g.before_all(function()
+    helpers.init_spaces(g)
+end)
+
+g.after_each(function()
+    helpers.truncate_spaces(g)
+end)
+
+function g.test_stats_basic()
+    local task = expirationd.start("stats_basic", g.tree.id, helpers.is_expired_true)
+    local stats = expirationd.stats("stats_basic")
+    t.assert_equals(stats, {
+        checked_count = 0,
+        expired_count = 0,
+        restarts = 1,
+        working_time = 0,
+    })
+    task:kill()
+end
+
+function g.test_stats_expired_count()
+    helpers.iteration_result = {}
+    g.hash:insert({1, "a"})
+    g.hash:insert({2, "b"})
+    g.hash:insert({3, "c"})
+
+    local task = expirationd.start("stats_expired_count", g.hash.id, helpers.is_expired_debug)
+    helpers.retrying({}, function()
+        t.assert_equals(helpers.iteration_result, {
+            {3, "c"},
+            {2, "b"},
+            {1, "a"}
+        })
+    end)
+    local stats = expirationd.stats("stats_expired_count")
+    t.assert_equals(stats, {
+        checked_count = 3,
+        expired_count = 3,
+        restarts = 1,
+        working_time = 0,
+    })
+    task:kill()
+end
+
+function g.test_stats_restarts()
+    local task = expirationd.start("stats_restarts", g.tree.id, helpers.is_expired_true)
+    task:restart()
+    task:restart()
+    local stats = expirationd.stats("stats_restarts")
+    t.assert_equals(stats, {
+        checked_count = 0,
+        expired_count = 0,
+        restarts = 3,
+        working_time = 0,
+    })
+    task:kill()
+end
+
+function g.test_stats_working_time()
+    local task = expirationd.start("stats_working_time", g.tree.id, helpers.is_expired_true)
+    local running_time = 1
+    local threshold = 0.3
+
+    local start_time = fiber.clock()
+    fiber.sleep(running_time)
+    local duration = fiber.clock() - start_time
+
+    local stats = expirationd.stats("stats_working_time")
+    t.assert_almost_equals(stats.working_time, duration, threshold)
+    stats.working_time = nil
+    t.assert_equals(stats, {
+        checked_count = 0,
+        expired_count = 0,
+        restarts = 1,
+    })
+    task:kill()
+end