Add unit test coverage for racing updaters (#2292)

It would be good to also add some coverage in
update_client::UrlFetcherDownloader; we can plan to do that in a
separate change.

b/309841211

Change-Id: I6505843004aafc920a1a7e84a6c61551dbbbb7a3

components/update_client/BUILD.gn

@@ -240,6 +240,7 @@ target(gtest_target_type, "cobalt_slot_management_test") {
     "//net:test_support",
     "//starboard/loader_app:app_key_files",
     "//starboard/loader_app:drain_file",
+    "//starboard/loader_app:drain_file_helper",
     "//starboard/loader_app:installation_manager",
     "//testing/gmock",
     "//testing/gtest",

components/update_client/cobalt_slot_management_test.cc

@@ -19,9 +19,11 @@
 
 #include "base/strings/string_util.h"
 #include "starboard/common/file.h"
+#include "starboard/common/time.h"
 #include "starboard/extension/free_space.h"
 #include "starboard/loader_app/app_key_files.h"
 #include "starboard/loader_app/drain_file.h"
+#include "starboard/loader_app/drain_file_helper.h"
 #include "starboard/loader_app/installation_manager.h"
 #include "starboard/loader_app/system_get_extension_shim.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -117,7 +119,7 @@ TEST_F(CobaltSlotManagementTest, SelectEmptySlot) {
                              base::CompareCase::SENSITIVE));
 }
 
-TEST_F(CobaltSlotManagementTest, SelectSlotBailOnDraining) {
+TEST_F(CobaltSlotManagementTest, SelectSlotBailsIfOtherAppIsDraining) {
   if (!storage_path_implemented_) {
     return;
   }
@@ -185,6 +187,31 @@ TEST_F(CobaltSlotManagementTest, ConfirmSlot) {
   ASSERT_EQ(IM_MAX_NUM_TRIES, ImGetInstallationNumTriesLeft(1));
 }
 
+// Tests the "racing updaters" scenario.
+TEST_F(CobaltSlotManagementTest, ConfirmSlotBailsIfOtherAppStartedDrainFirst) {
+  if (!storage_path_implemented_) {
+    return;
+  }
+
+  CobaltSlotManagement cobalt_slot_management;
+  std::string slot_path = storage_path_;
+  slot_path += kSbFileSepString;
+  slot_path += "installation_1";
+  ASSERT_TRUE(cobalt_slot_management.Init(api_));
+  base::FilePath dir;
+  ASSERT_TRUE(cobalt_slot_management.SelectSlot(&dir));
+
+  // In order to be higher ranked, the other app's drain file needs to be older
+  // but not expired.
+  int64_t current_time_us =
+      starboard::PosixTimeToWindowsTime(starboard::CurrentPosixTime());
+  starboard::loader_app::ScopedDrainFile racing_drain_file(
+      slot_path, kTestAppKey2,
+      current_time_us - (kDrainFileMaximumAgeUsec / 2));
+
+  ASSERT_FALSE(cobalt_slot_management.ConfirmSlot(dir));
+}
+
 TEST_F(CobaltSlotManagementTest, CleanupAllDrainFiles) {
   if (!storage_path_implemented_) {
     return;

starboard/loader_app/BUILD.gn

@@ -197,16 +197,28 @@ static_library("drain_file") {
   deps = [ "//starboard/common" ]
 }
 
-target(gtest_target_type, "drain_file_test") {
+static_library("drain_file_helper") {
   testonly = true
   sources = [
-    "//starboard/common/test_main.cc",
     "drain_file_helper.cc",
     "drain_file_helper.h",
+  ]
+  deps = [
+    ":drain_file",
+    "//starboard/common",
+    "//testing/gtest",
+  ]
+}
+
+target(gtest_target_type, "drain_file_test") {
+  testonly = true
+  sources = [
+    "//starboard/common/test_main.cc",
     "drain_file_test.cc",
   ]
   deps = [
     ":drain_file",
+    ":drain_file_helper",
     "//testing/gmock",
     "//testing/gtest",
   ]

starboard/loader_app/drain_file_test.cc

@@ -207,6 +207,16 @@ TEST_F(DrainFileTest, SunnyDayRankCorrectlyIgnoresExpired) {
   EXPECT_TRUE(SbFileDelete(early_and_expired.path().c_str()));
 }
 
+// Tests the "racing updaters" scenario.
+TEST_F(DrainFileTest, RankAndCheckWithFirstRankedFileFromOtherAppReturnsFalse) {
+  const int64_t timestamp = PosixTimeToWindowsTime(CurrentPosixTime());
+
+  ScopedDrainFile earlier(GetTempDir(), "a", timestamp);
+  ScopedDrainFile later(GetTempDir(), "b", timestamp + kDrainFileAgeUnitUsec);
+
+  EXPECT_FALSE(DrainFileRankAndCheck(GetTempDir(), "b"));
+}
+
 // All files in the directory should be cleared except for drain files with an
 // app key matching the provided app key.
 TEST_F(DrainFileTest, SunnyDayPrepareDirectory) {