From b3a8706c2f809bc2d09b182c262de3b9509584fa Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Mon, 27 Jan 2020 13:23:09 -0800
Subject: [PATCH] Fabric: Basic tests for MountingTelemetry

Summary:
Some tests which will be useful for the next diff.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: mdvacca

Differential Revision: D19482255

fbshipit-source-id: 3384662477f750620a37acc4a277a55c2dbd8d0e
---
 .../mounting/tests/MountingTelemetryTest.cpp  | 90 +++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 ReactCommon/fabric/mounting/tests/MountingTelemetryTest.cpp

diff --git a/ReactCommon/fabric/mounting/tests/MountingTelemetryTest.cpp b/ReactCommon/fabric/mounting/tests/MountingTelemetryTest.cpp
new file mode 100644
index 00000000000..391e1d088e8
--- /dev/null
+++ b/ReactCommon/fabric/mounting/tests/MountingTelemetryTest.cpp
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <chrono>
+#include <thread>
+
+#include <gtest/gtest.h>
+
+#include <react/mounting/MountingTelemetry.h>
+
+using namespace facebook::react;
+
+#define EXPECT_EQ_WITH_THRESHOLD(a, b, threshold) \
+  EXPECT_TRUE((a >= b - threshold) && (a <= b + threshold))
+
+TEST(MountingTelemetryTest, normalUseCase) {
+  auto threshold = int64_t{30};
+  auto telemetry = MountingTelemetry{};
+
+  telemetry.willCommit();
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  telemetry.willLayout();
+  std::this_thread::sleep_for(std::chrono::milliseconds(200));
+  telemetry.didLayout();
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  telemetry.didCommit();
+
+  std::this_thread::sleep_for(std::chrono::milliseconds(300));
+
+  telemetry.willMount();
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  telemetry.didMount();
+
+  auto commitDuration =
+      telemetry.getCommitEndTime() - telemetry.getCommitStartTime();
+  auto layoutDuration =
+      telemetry.getLayoutEndTime() - telemetry.getLayoutStartTime();
+  auto mountDuration =
+      telemetry.getMountEndTime() - telemetry.getMountStartTime();
+
+  EXPECT_EQ_WITH_THRESHOLD(commitDuration, 400, threshold);
+  EXPECT_EQ_WITH_THRESHOLD(layoutDuration, 200, threshold);
+  EXPECT_EQ_WITH_THRESHOLD(mountDuration, 100, threshold);
+}
+
+TEST(MountingTelemetryTest, abnormalUseCases) {
+  // Calling `did` before `will` should crash.
+  EXPECT_DEATH_IF_SUPPORTED(
+      {
+        auto telemetry = MountingTelemetry{};
+        telemetry.didDiff();
+      },
+      "diffStartTime_");
+
+  EXPECT_DEATH_IF_SUPPORTED(
+      {
+        auto telemetry = MountingTelemetry{};
+        telemetry.didCommit();
+      },
+      "commitStartTime_");
+
+  EXPECT_DEATH_IF_SUPPORTED(
+      {
+        auto telemetry = MountingTelemetry{};
+        telemetry.didMount();
+      },
+      "mountStartTime_");
+
+  // Getting `start` *or* `end` timepoints before a pair of `will` and `did`
+  // should crash.
+  EXPECT_DEATH_IF_SUPPORTED(
+      {
+        auto telemetry = MountingTelemetry{};
+        telemetry.willCommit();
+        telemetry.getCommitStartTime();
+      },
+      "commitEndTime_");
+
+  EXPECT_DEATH_IF_SUPPORTED(
+      {
+        auto telemetry = MountingTelemetry{};
+        telemetry.willCommit();
+        telemetry.getCommitEndTime();
+      },
+      "commitEndTime_");
+}