cc cache: rewrite cache metrics test without Sleep

commit_hash:497182db302efe8a0dd897ed1a508f0018d00c5d

Author: Anton3

.mapping.json

@@ -1208,6 +1208,7 @@
   "core/src/cache/cache_config.cpp":"taxi/uservices/userver/core/src/cache/cache_config.cpp",
   "core/src/cache/cache_dependencies.cpp":"taxi/uservices/userver/core/src/cache/cache_dependencies.cpp",
   "core/src/cache/cache_dependencies.hpp":"taxi/uservices/userver/core/src/cache/cache_dependencies.hpp",
+  "core/src/cache/cache_metrics_initialization_test.cpp":"taxi/uservices/userver/core/src/cache/cache_metrics_initialization_test.cpp",
   "core/src/cache/cache_statistics.cpp":"taxi/uservices/userver/core/src/cache/cache_statistics.cpp",
   "core/src/cache/cache_update_trait.cpp":"taxi/uservices/userver/core/src/cache/cache_update_trait.cpp",
   "core/src/cache/cache_update_trait_impl.cpp":"taxi/uservices/userver/core/src/cache/cache_update_trait_impl.cpp",
@@ -1298,7 +1299,6 @@
   "core/src/clients/http/streamed_response.cpp":"taxi/uservices/userver/core/src/clients/http/streamed_response.cpp",
   "core/src/clients/http/testsuite.hpp":"taxi/uservices/userver/core/src/clients/http/testsuite.hpp",
   "core/src/clients/http/tracing_manager_test.cpp":"taxi/uservices/userver/core/src/clients/http/tracing_manager_test.cpp",
-  "core/src/components/cache_metrics_initialization_test.cpp":"taxi/uservices/userver/core/src/components/cache_metrics_initialization_test.cpp",
   "core/src/components/common_component_list.cpp":"taxi/uservices/userver/core/src/components/common_component_list.cpp",
   "core/src/components/common_component_list_test.cpp":"taxi/uservices/userver/core/src/components/common_component_list_test.cpp",
   "core/src/components/common_server_component_list.cpp":"taxi/uservices/userver/core/src/components/common_server_component_list.cpp",

…ts/cache_metrics_initialization_test.cpp …he/cache_metrics_initialization_test.cppcore/src/components/cache_metrics_initialization_test.cpp renamed to core/src/cache/cache_metrics_initialization_test.cpp core/src/components/cache_metrics_initialization_test.cpp renamed to core/src/cache/cache_metrics_initialization_test.cpp

@@ -10,6 +10,7 @@
 #include <userver/components/run.hpp>
 #include <userver/components/statistics_storage.hpp>
 #include <userver/engine/deadline.hpp>
+#include <userver/engine/single_consumer_event.hpp>
 #include <userver/engine/sleep.hpp>
 #include <userver/testsuite/testsuite_support.hpp>
 #include <userver/utest/utest.hpp>
@@ -19,6 +20,8 @@ USERVER_NAMESPACE_BEGIN
 
 namespace {
 
+engine::SingleConsumerEvent checked_metrics_before_update;
+
 const auto kStaticConfig = tests::MergeYaml(tests::kMinimalStaticConfig, R"(
 components_manager:
     components:
@@ -47,8 +50,9 @@ class ToyCache final : public components::CachingComponentBase<int> {
         const std::chrono::system_clock::time_point& /*now*/,
         cache::UpdateStatisticsScope& stats_scope
     ) override {
-        // Simulate a 3-second update.
-        engine::SleepFor(std::chrono::seconds(3));
+        // Wait until the checker component checks metrics at least once.
+        const bool wait_succeeded = checked_metrics_before_update.WaitForEventFor(utest::kMaxTestWaitTime);
+        EXPECT_TRUE(wait_succeeded) << "Timed out waiting for metrics checker";
 
         // Complete successfully with size 10.
         Set(10);
@@ -98,6 +102,9 @@ class MetricsChecker final : public components::ComponentBase {
                 cache_size_seen = true;
             }
 
+            // Signal to the cache that we checked the metrics state.
+            checked_metrics_before_update.Send();
+
             // If both metrics are set, we're done.
             if (cache_age_seen && cache_size_seen) {
                 break;
@@ -115,6 +122,8 @@ class CacheMetricsInitializationTest : public ComponentList {};
 }  // namespace
 
 TEST_F(CacheMetricsInitializationTest, MetricsNotWrittenBeforeInitialization) {
+    checked_metrics_before_update.Reset();
+
     components::RunOnce(
         components::InMemoryConfig{kStaticConfig},
         components::MinimalComponentList()