[fuchsia] Adds a test for clock change (#19993)

This is a Fuchsia-only shell test, confirming that when the timezone
setting is changed on the realm via Fuchsia's FIDL interface
`fuchsia.settings.Intl`, the Dart isolate running in that realm receives
the change and starts reporting the appropriate timestamp.

We already have a [similar test][tst] that verifies the timezones in the
dart VM matches the local timezone at start, but there was no test that
also verified timezone changes.

[tst]: https://github.com/flutter/engine/blob/master/shell/common/shell_unittests.cc#L1166

See issue #61284

ci/licenses_golden/licenses_flutter

@@ -624,6 +624,7 @@ FILE: ../../../flutter/shell/common/serialization_callbacks.h
 FILE: ../../../flutter/shell/common/shell.cc
 FILE: ../../../flutter/shell/common/shell.h
 FILE: ../../../flutter/shell/common/shell_benchmarks.cc
+FILE: ../../../flutter/shell/common/shell_fuchsia_unittests.cc
 FILE: ../../../flutter/shell/common/shell_io_manager.cc
 FILE: ../../../flutter/shell/common/shell_io_manager.h
 FILE: ../../../flutter/shell/common/shell_test.cc

shell/common/BUILD.gn

@@ -263,5 +263,16 @@ if (enable_unittests) {
       "//flutter/shell/version",
       "//third_party/googletest:gmock",
     ]
+
+    if (is_fuchsia) {
+      sources += [ "shell_fuchsia_unittests.cc" ]
+
+      deps += [
+        "$fuchsia_sdk_root/fidl:fuchsia.intl",
+        "$fuchsia_sdk_root/fidl:fuchsia.settings",
+        "$fuchsia_sdk_root/pkg:fidl_cpp",
+        "$fuchsia_sdk_root/pkg:sys_cpp",
+      ]
+    }
   }
 }

shell/common/fixtures/shell_test.dart

@@ -141,12 +141,29 @@ List<int> getFixtureImage() native 'GetFixtureImage';
 
 void notifyLocalTime(String string) native 'NotifyLocalTime';
 
-@pragma('vm:entry-point')
-void localtimesMatch() {
+void waitFixture() native 'WaitFixture';
+
+// Return local date-time as a string, to an hour resolution.  So, "2020-07-23
+// 14:03:22" will become "2020-07-23 14".
+String localTimeAsString() {
   final now = DateTime.now().toLocal();
   // This is: "$y-$m-$d $h:$min:$sec.$ms$us";
   final timeStr = now.toString();
   // Forward only "$y-$m-$d $h" for timestamp comparison.  Not using DateTime
   // formatting since package:intl is not available.
-  notifyLocalTime(timeStr.split(":")[0]);
+  return timeStr.split(":")[0];
+}
+
+@pragma('vm:entry-point')
+void localtimesMatch() {
+  notifyLocalTime(localTimeAsString());
+}
+
+@pragma('vm:entry-point')
+void timezonesChange() {
+  notifyLocalTime(localTimeAsString());
+  waitFixture();
+  notifyLocalTime(localTimeAsString());
+  waitFixture();
+  notifyLocalTime(localTimeAsString());
 }

shell/common/shell_fuchsia_unittests.cc

+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// A fuchsia-specific shell test.
+//
+// This test is only supposed to be ran on Fuchsia OS, as it exercises
+// Fuchsia-specific functionality for which no equivalent exists elsewhere.
+
+#define FML_USED_ON_EMBEDDER
+
+#include <time.h>
+#include <unistd.h>
+
+#include <memory>
+
+#include <fuchsia/intl/cpp/fidl.h>
+#include <fuchsia/settings/cpp/fidl.h>
+#include <lib/sys/cpp/component_context.h>
+
+#include "flutter/fml/synchronization/count_down_latch.h"
+#include "flutter/runtime/dart_vm.h"
+#include "flutter/shell/common/shell_test.h"
+
+namespace flutter {
+namespace testing {
+
+using fuchsia::intl::TimeZoneId;
+using fuchsia::settings::Intl_Set_Result;
+using fuchsia::settings::IntlSettings;
+
+class FuchsiaShellTest : public ShellTest {
+ protected:
+  FuchsiaShellTest()
+      : ctx_(sys::ComponentContext::CreateAndServeOutgoingDirectory()),
+        intl_() {
+    ctx_->svc()->Connect(intl_.NewRequest());
+  }
+
+  ~FuchsiaShellTest() {
+    // Restore the time zoe that matche that of the test harness.  This is
+    // the default.
+    const std::string local_timezone = GetLocalTimezone();
+    SetTimezone(local_timezone);
+    AssertTimezone(local_timezone, GetSettings());
+  }
+
+  // Gets the international settings from this Fuchsia realm.
+  IntlSettings GetSettings() {
+    IntlSettings settings;
+    zx_status_t status = intl_->Watch2(&settings);
+    EXPECT_EQ(status, ZX_OK);
+    return settings;
+  }
+
+  // Sets the timezone of this Fuchsia realm to `timezone_name`.
+  void SetTimezone(const std::string& timezone_name) {
+    fuchsia::settings::IntlSettings settings;
+    settings.set_time_zone_id(TimeZoneId{.id = timezone_name});
+    Intl_Set_Result result;
+    zx_status_t status = intl_->Set(std::move(settings), &result);
+    ASSERT_EQ(status, ZX_OK);
+  }
+
+  std::string GetLocalTimezone() {
+    const time_t timestamp = time(nullptr);
+    const struct tm* local_time = localtime(&timestamp);
+    EXPECT_NE(local_time, nullptr)
+        << "Could not get local time: errno=" << errno << ": "
+        << strerror(errno);
+    return std::string(local_time->tm_zone);
+  }
+
+  // Checks that the timezone name in the `settings` matches what is `expected`.
+  void AssertTimezone(const std::string& expected,
+                      const IntlSettings& settings) {
+    ASSERT_EQ(expected, settings.time_zone_id().id);
+  }
+
+  std::unique_ptr<sys::ComponentContext> ctx_;
+  fuchsia::settings::IntlSyncPtr intl_;
+
+  fuchsia::settings::IntlSettings save_settings_;
+};
+
+static bool ValidateShell(Shell* shell) {
+  if (!shell) {
+    return false;
+  }
+
+  if (!shell->IsSetup()) {
+    return false;
+  }
+
+  ShellTest::PlatformViewNotifyCreated(shell);
+
+  {
+    fml::AutoResetWaitableEvent latch;
+    fml::TaskRunner::RunNowOrPostTask(
+        shell->GetTaskRunners().GetPlatformTaskRunner(), [shell, &latch]() {
+          shell->GetPlatformView()->NotifyDestroyed();
+          latch.Signal();
+        });
+    latch.Wait();
+  }
+
+  return true;
+}
+
+// Verifies that changing the Fuchsia settings timezone through the FIDL
+// settings interface results in a change of the reported local time in the
+// isolate.
+//
+// The test is as follows:
+//
+// - Set an initial timezone, then get a timestamp from the isolate rounded down
+//   to the nearest hour.  The assumption is as long as this test doesn't run
+//   very near the whole hour, which should be very unlikely, the nearest hour
+//   will vary depending on the time zone.
+// - Set a different timezone.  Get a timestamp from the isolate again and
+//   confirm that this time around the timestamps are different.
+// - Set the initial timezone again, and get the timestamp.  This time, the
+//   timestamp rounded down to whole hour should match the timestamp we got
+//   in the initial step.
+TEST_F(FuchsiaShellTest, LocaltimesVaryOnTimezoneChanges) {
+  // Start with a set timezone.   System timezone will be restored at test
+  // teardown.
+  SetTimezone("Europe/Amsterdam");
+  AssertTimezone("Europe/Amsterdam", GetSettings());
+
+  // See fixtures/shell_test.dart, the callback NotifyLocalTime is declared
+  // there.
+  fml::AutoResetWaitableEvent latch;
+  std::string dart_isolate_time_str;
+  AddNativeCallback("NotifyLocalTime", CREATE_NATIVE_ENTRY([&](auto args) {
+                      dart_isolate_time_str =
+                          tonic::DartConverter<std::string>::FromDart(
+                              Dart_GetNativeArgument(args, 0));
+                      latch.Signal();
+                    }));
+
+  fml::AutoResetWaitableEvent fixture_latch;
+  AddNativeCallback("WaitFixture", CREATE_NATIVE_ENTRY([&](auto args) {
+                      // Wait for the test fixture to advance.
+                      fixture_latch.Wait();
+                    }));
+
+  auto settings = CreateSettingsForFixture();
+  auto configuration = RunConfiguration::InferFromSettings(settings);
+  configuration.SetEntrypoint("timezonesChange");
+
+  std::unique_ptr<Shell> shell = CreateShell(settings);
+  ASSERT_NE(shell.get(), nullptr);
+  ASSERT_TRUE(ValidateShell(shell.get()));
+  RunEngine(shell.get(), std::move(configuration));
+  latch.Wait();
+
+  // Save the first reported local time.
+  const std::string initial_dart_isolate_time_str = dart_isolate_time_str;
+
+  SetTimezone("America/New_York");
+  AssertTimezone("America/New_York", GetSettings());
+
+  // Allow the dart program to advance.
+  fixture_latch.Signal();
+  // Wait until the isolate processes the timezone update.
+  latch.Wait();
+
+  const std::string modified_dart_isolate_time_str = dart_isolate_time_str;
+
+  ASSERT_NE(initial_dart_isolate_time_str, modified_dart_isolate_time_str)
+      << "Local time clocks in Europe/Amsterdam and America/New_York "
+      << "should never be the same but this test says they are; time zone "
+      << "handling in the dart VM is likely broken.";
+
+  // Set the timezone back to the original one we started from, and verify
+  // that the timestamp (to the resolution of 1 hour) match.
+  SetTimezone("Europe/Amsterdam");
+  AssertTimezone("Europe/Amsterdam", GetSettings());
+
+  // Allow the dart program to advance.
+  fixture_latch.Signal();
+  // Wait until the isolate processes the timezone update.
+  latch.Wait();
+
+  const std::string final_dart_isolate_time_str = dart_isolate_time_str;
+
+  ASSERT_EQ(initial_dart_isolate_time_str, final_dart_isolate_time_str)
+      << "Local time in Europe/Amsterdam rounded down to nearest hour read "
+         "twice"
+      << "should be the same but this test says they are not; time zone "
+      << "handling in the dart VM is likely broken.";
+
+  DestroyShell(std::move(shell));
+}
+
+}  // namespace testing
+}  // namespace flutter

testing/fuchsia/meta/fuchsia_test.cmx

@@ -11,13 +11,14 @@
     ],
     "services": [
       "fuchsia.accessibility.semantics.SemanticsManager",
-      "fuchsia.process.Launcher",
       "fuchsia.deprecatedtimezone.Timezone",
+      "fuchsia.logger.LogSink",
       "fuchsia.netstack.Netstack",
+      "fuchsia.process.Launcher",
+      "fuchsia.settings.Intl",
       "fuchsia.sysmem.Allocator",
-      "fuchsia.vulkan.loader.Loader",
-      "fuchsia.logger.LogSink",
       "fuchsia.tracing.provider.Registry",
+      "fuchsia.vulkan.loader.Loader",
       "fuchsia.intl.PropertyProvider"
     ]
   }