### Setup Emulator and PM Serve

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/fuchsia/dart_runner/tests/startup_integration_test/dart_aot_runner/README.md

Initializes the Fuchsia environment by setting up the emulator and starting the package serving daemon.

```bash
fx set terminal.qemu-x64
ffx emu start --headless

fx serve
```

--------------------------------

### Setup and Run Tests

Source: https://github.com/flutter-team-archive/engine/blob/main/tools/compare_goldens/README.md

Install dependencies and run all Dart tests in the project. Ensure assertions are enabled for testing.

```sh
dart pub get
find . -name "*_test.dart" | xargs -n 1 dart --enable-asserts
```

--------------------------------

### Starting DDS and Serving DevTools

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/Using-the-Dart-Development-Service-(DDS)-and-Flutter-DevTools-with-a-custom-Flutter-Engine-Embedding.md

Example of running the `dart development-service` command with the required `--vm-service-uri` and the `--serve-devtools` flag. The output shows the connection URIs for DDS and DevTools.

```bash
$ dart development-service --vm-service-uri=http://127.0.0.1:59113/BBPoXnZUWFU=/ --serve-devtools
{"state":"started","ddsUri":"http://127.0.0.1:59123/tbrR0DzW2j8=/","devToolsUri":"http://127.0.0.1:59123/tbrR0DzW2j8=/devtools?uri=ws://127.0.0.1:59123/tbrR0DzW2j8=/ws","dtd":{"uri":"ws://127.0.0.1:59122/R1LbdlhtkUygRWNA"}}
```

--------------------------------

### Run Example App with Local Engine

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/android/README.md

Run an example application, such as the video_player example, using a locally built Flutter engine. This is useful for testing specific package integrations.

```shell
flutter run \
  --local-engine-host=$ENGINE/out/host_debug_unopt_arm64 \
  --local-engine=$ENGINE/out/android_debug_unopt_arm64
```

--------------------------------

### Example: Run 'embedder' Integration Test

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/fuchsia/flutter/tests/integration/README.md

An example demonstrating how to run the 'embedder' integration test suite with the `--no-lto` flag.

```shell
$ENGINE_DIR/flutter/tools/fuchsia/devshell/run_integration_test.sh embedder --no-lto
```

--------------------------------

### Start Fuchsia package server

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/fuchsia/flutter/tests/integration/touch-input/README.md

Starts a package server for Fuchsia, which is necessary for publishing and serving packages to the Fuchsia device or emulator. Navigate to your Fuchsia directory before running.

```shell
cd "$FUCHSIA_DIR"
fx serve
```

--------------------------------

### Start Fuchsia emulator

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/fuchsia/flutter/tests/integration/touch-input/README.md

Launches the Fuchsia emulator. This command is used to start a graphical instance of the Fuchsia operating system for testing.

```shell
ffx emu start
```

--------------------------------

### Get Help for run_tests.py

Source: https://github.com/flutter-team-archive/engine/blob/main/testing/ios/IosUnitTests/README.md

View available options and usage instructions for the `run_tests.py` script.

```sh
flutter/testing/run_tests.py --help
```

--------------------------------

### GLFW Example Embedder

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/Custom-Flutter-Engine-Embedders.md

This example embedder uses GLFW for window management and rendering, serving as a guide for custom embedder development.

```cc
examples/glfw/FlutterEmbedderGLFW.cc
```

--------------------------------

### Install FlameGraph Swift Tool

Source: https://github.com/flutter-team-archive/engine/blob/main/impeller/docs/ios_cpu_profile.md

Install the FlameGraph Swift command-line tool using Mint. This tool is used to convert captured profile data into HTML Flame Graphs.

```shell
mint install lennet/FlameGraph
```

--------------------------------

### Launching DevTools with VM Service URI

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/Using-the-Dart-Development-Service-(DDS)-and-Flutter-DevTools-with-a-custom-Flutter-Engine-Embedding.md

Demonstrates starting Flutter DevTools by providing the VM service URI as a positional argument. If DDS is not running, this command will start it automatically.

```bash
$ dart devtools http://127.0.0.1:59251/2LS6f3Kb2JI=/
Started the Dart Development Service (DDS) at http://127.0.0.1:59260/38XeuQpIHRE=/
Serving DevTools at http://127.0.0.1:9101.

          Hit ctrl-c to terminate the server.
```

--------------------------------

### Empty Build Configuration File

Source: https://github.com/flutter-team-archive/engine/blob/main/ci/builders/README.md

An example of an empty build configuration JSON file. Tests, generators, and archives can be omitted if they are empty.

```json
{
   "builds": [],
   "tests": [],
   "generators": {
       "tasks": []
   },
   "archives": [
   ]
}
```

--------------------------------

### Example CI Failure Output

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/embedder/fixtures/README.md

This is an example of what a test failure might look like on a CI environment, showing image mismatch errors.

```txt
[0;32m[ RUN      ] EmbedderTest.VerifyB143464703WithSoftwareBackend\n[ERROR:flutter/shell/platform/embedder/tests/embedder_unittests_util.cc(199)] Image did not match expectation.\nExpected:/b/s/w/ir/cache/builder/src/out/host_debug_unopt/gen/flutter/shell/platform/embedder/assets/expectation_verifyb143464703_soft_noxform.png\nGot:/b/s/w/ir/cache/builder/src/out/host_debug_unopt/gen/flutter/shell/platform/embedder/assets/actual_verifyb143464703_soft_noxform.png\n\n../../flutter/shell/platform/embedder/tests/embedder_unittests.cc:1335: Failure\nValue of: ImageMatchesFixture("verifyb143464703_soft_noxform.png", rendered_scene)\n  Actual: false\nExpected: true\n[  FAILED  ] EmbedderTest.VerifyB143464703WithSoftwareBackend (8077 ms)\n[----------] 1 test from EmbedderTest (8080 ms total)\n\n[----------] Global test environment tear-down\n[==========] 1 test from 1 test suite ran. (8080 ms total)\n[  PASSED  ] 0 tests.\n[  FAILED  ] 1 test, listed below:\n[  FAILED  ] EmbedderTest.VerifyB143464703WithSoftwareBackend\n\n 1 FAILED TEST\n[13/296] EmbedderTest.VerifyB143464703WithSoftwareBackend returned/aborted with exit code 1 (8226 ms)\n[14/296] EmbedderTest.VerifyB143464703WithSoftwareBackend (8484 ms)\n[INFO:test_timeout_listener.cc(76)] Test timeout of 300 seconds per test case will be enforced.\nNote: Google Test filter = EmbedderTest.VerifyB143464703WithSoftwareBackend\n[==========] Running 1 test from 1 test suite.\n[----------] Global test environment set-up.\n[----------] 1 test from EmbedderTest\n[ DISABLED ] EmbedderTest.DISABLED_CanLaunchAndShutdownMultipleTimes\n[ RUN      ] EmbedderTest.VerifyB143464703WithSoftwareBackend\n[ERROR:flutter/shell/platform/embedder/tests/embedder_unittests_util.cc(199)] Image did not match expectation.\nExpected:/b/s/w/ir/cache/builder/src/out/host_debug_unopt/gen/flutter/shell/platform/embedder/assets/expectation_verifyb143464703_soft_noxform.png\nGot:/b/s/w/ir/cache/builder/src/out/host_debug_unopt/gen/flutter/shell/platform/embedder/assets/actual_verifyb143464703_soft_noxform.png\n\n../../flutter/shell/platform/embedder/tests/embedder_unittests.cc:1335: Failure\nValue of: ImageMatchesFixture("verifyb143464703_soft_noxform.png", rendered_scene)\n  Actual: false\nExpected: true\n[  FAILED  ] EmbedderTest.VerifyB143464703WithSoftwareBackend (8348 ms)\n[----------] 1 test from EmbedderTest (8350 ms total)\n\n[----------] Global test environment tear-down\n[==========] 1 test from 1 test suite ran. (8350 ms total)\n[  PASSED  ] 0 tests.\n[  FAILED  ] 1 test, listed below:\n[  FAILED  ] EmbedderTest.VerifyB143464703WithSoftwareBackend\n
```

--------------------------------

### Example linux_host_engine Target Configuration

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/ci/Engine-pre-submits-and-post-submits.md

This JSON configuration defines the parameters for the `linux_host_engine` target, which is part of the pre-submit checks.

```json
{
  "name": "linux_host_engine",
  "recipe": "engine_v2/engine_v2",
  "platform": "linux",
  "tests": [
    {
      "name": "linux_host_engine_unopt_test",
      "test": "flutter/engine/src/test/engine_test.dart",
      "args": ["--no-enable-impeller"]
    }
  ]
}
```

--------------------------------

### Install Mint Package Manager

Source: https://github.com/flutter-team-archive/engine/blob/main/impeller/docs/ios_cpu_profile.md

Install the Mint package manager using Homebrew. Ensure your shell's profile is updated to include Mint's binary directory in your PATH.

```shell
brew install mint
```

```shell
echo 'export PATH="$PATH:$HOME/.mint/bin"' >> ~/.profile
source ~/.profile
```

--------------------------------

### Configure GN Flags

Source: https://github.com/flutter-team-archive/engine/blob/main/ci/builders/README.md

Provides flags to the tools/gn script for configuring the build. This example sets runtime mode to debug, uses a prebuilt Dart SDK, and builds embedder examples.

```json
"gn": [
      "--runtime-mode",
      "debug",
      "--prebuilt-dart-sdk",
      "--build-embedder-examples"
],
```

--------------------------------

### Sample CI Build Configuration

Source: https://github.com/flutter-team-archive/engine/blob/main/ci/builders/README.md

This YAML configuration shows how a build definition file is referenced within a CI setup. It specifies the recipe to use and properties like the SDK version.

```yaml
  - name: Mac mac_android_aot_engine
    recipe: engine_v2/engine_v2
    timeout: 60
    properties:
      config_name: mac_android_aot_engine
      $flutter/osx_sdk : >-
        { "sdk_version": "15a240d" }


```

--------------------------------

### Get Help for CLI

Source: https://github.com/flutter-team-archive/engine/blob/main/tools/gen_web_locale_keymap/README.md

Display help information for the command-line interface of the generator script.

```bash
dart --enable-asserts bin/gen_web_locale_keymap.dart -h
```

--------------------------------

### Make EGL Context Current

Source: https://github.com/flutter-team-archive/engine/blob/main/impeller/docs/standalone_gles.md

Makes the created EGL context current on the calling thread, completing the WSI setup.

```c++
context->MakeCurrent(*surface);
```

--------------------------------

### Publish touch-input-view package

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/fuchsia/flutter/tests/integration/touch-input/README.md

Publishes the `touch-input-view` component package to the Fuchsia package server. This makes the component available for installation on the target system.

```shell
$FUCHSIA_DIR/.jiri_root/bin/fx pm publish -a -repo $FUCHSIA_DIR/$(cat $FUCHSIA_DIR/.fx-build-dir)/amber-files -f $ENGINE_DIR/out/
fuchsia_debug_x64/gen/flutter/shell/platform/fuchsia/flutter/tests/integration/touch-input/touch-input-view/touch-input-view/touch-input-view.far
```

--------------------------------

### Run clang-tidy with Multiple Checks using Wildcards

Source: https://github.com/flutter-team-archive/engine/blob/main/tools/clang_tidy/README.md

Add multiple checks to the clang-tidy run using wildcards with the `--checks` flag. For example, to include all checks starting with `readability-`.

```shell
dart ./tools/clang_tidy/bin/main.dart --checks="readability-*"
```

--------------------------------

### Prepare Build Files (Windows)

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Use the gn tool to prepare build files for an unoptimized build on Windows. For gen_snapshot only, specify runtime mode and optional --android flag.

```bash
python .\flutter\tools\gn --unoptimized
```

```bash
python .\flutter\tools\gn [--unoptimized] --runtime-mode=[debug|profile|release] [--android]
```

--------------------------------

### CheckedNumeric<> Example Usage

Source: https://github.com/flutter-team-archive/engine/blob/main/third_party/accessibility/base/numerics/README.md

Example demonstrating the usage of CheckedNumeric<> and its boundary condition detection.

```APIDOC
## CheckedNumeric<> Example Usage

### Description
This example demonstrates the usage of `CheckedNumeric<>` and its boundary condition detection.

### Code Example
```cpp
#include "base/numerics/checked_math.h"
...
CheckedNumeric<uint32_t> variable = 0;
variable++;
variable--;
if (variable.ValueOrDie() == 0)
  // Fine, |variable| still within valid range.

variable--;
variable++;
if (variable.ValueOrDie() == 0)  // Breakpoint or configured CheckHandler
  // Does not happen as variable underflowed.
```

### Pattern for Safe Operations
Comparison operators are explicitly not provided for `CheckedNumeric` types because they could result in a crash if the type is not in a valid state. Patterns like the following should be used instead:

### Code Example
```cpp
// Either input or padding (or both) may be arbitrary sizes.
size_t buff_size;
if (!CheckAdd(input, padding, kHeaderLength).AssignIfValid(&buff_size) ||
     buff_size >= kMaxBuffer) {
  // Handle an error...
} else {
  // Do stuff on success...
}
```
```

--------------------------------

### Prepare Build Files for Host-Side Executables

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Use this command to prepare build files for host-side executables. On Apple Silicon, add `--mac-cpu arm64` to avoid emulation and generate `host_debug_unopt_arm64`.

```bash
./flutter/tools/gn --unoptimized
```

--------------------------------

### Install ImageMagick on MacOS

Source: https://github.com/flutter-team-archive/engine/blob/main/tools/build_bucket_golden_scraper/README.md

Install ImageMagick using Homebrew for enhanced image diffing capabilities with git.

```shell
# On MacOS.
$ brew install imagemagick
```

--------------------------------

### Prepare Build Files for iOS Device Executables

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Use this command to prepare build files for device-side executables. Add `--simulator --unoptimized` for simulator builds. For arm64 Mac simulators, include `--simulator-cpu=arm64`.

```bash
./flutter/tools/gn --ios --unoptimized
```

--------------------------------

### Create and Navigate to Engine Directory

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Setting-up-the-Engine-development-environment.md

Create a new directory for the engine source code and change into it.

```sh
mkdir engine; cd engine;
```

--------------------------------

### Prepare Build Files and Build Binary

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/fuchsia/dart_runner/tests/startup_integration_test/dart_jit_runner/README.md

Generate build files using the Flutter GN tool and then build the necessary binaries using Ninja. This step is crucial for creating the test artifacts.

```bash
$ENGINE_DIR/flutter/tools/gn --fuchsia --no-lto
ninja -C $ENGINE_DIR/out/fuchsia_debug_x64 flutter/shell/platform/fuchsia fuchsia_tests
```

--------------------------------

### Install Emulator Component

Source: https://github.com/flutter-team-archive/engine/blob/main/testing/scenario_app/android/README.md

Update the vendored Android emulator to resolve known issues, such as problems with Vulkan. This command installs the latest emulator version using the sdkmanager.

```sh
$ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager --install emulator
```

--------------------------------

### Compile Schemas with glib-compile-schemas

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/linux/testing/gschemas/README.md

Download the gsettings-desktop-schemas package, extract its contents, and then compile the schemas using `glib-compile-schemas`. Ensure the target directory is correctly specified.

```bash
# download gsettings-desktop-schemas package
wget http://archive.ubuntu.com/ubuntu/pool/main/g/gsettings-desktop-schemas/gsettings-desktop-schemas_<version>.deb

# extract schema sources (/usr/share/glib-2.0/schemas/*.gschema.xml & .override)
ar x gsettings-desktop-schemas_<version>.deb
tar xf data.tar.zst

# compile schemas (/usr/share/glib-2.0/schemas/gschemas.compiled)
glib-compile-schemas --targetdir path/to/testing/gschemas usr/share/glib-2.0/schemas/
```

--------------------------------

### List Available Builds with et

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/rbe/rbe.md

View all available build configurations for the `et` tool. Use the `--verbose` flag to see builds that match CI configurations.

```bash
et help build --verbose
```

--------------------------------

### Get Thread Backtrace in LLDB

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/Crashes.md

Command to get the current thread's backtrace in LLDB. Assumes you are on the crashed thread; if not, use 'thread select n' first.

```bash
thread backtrace
```

--------------------------------

### Build and Run Android Display List Benchmarks

Source: https://github.com/flutter-team-archive/engine/blob/main/testing/benchmark/README_displaylist.md

Build the display_list_benchmarks binary for Android and push it to the device using adb. The binary is then executed via adb shell, with results piped to a JSON file. Ensure the binary is placed on a non-exec mount point like /data/local/tmp.

```bash
$ adb push out/android_profile_arm64/display_list_benchmarks /data/local/tmp/display_list_benchmarks
$ adb shell /data/local/tmp/display_list_benchmarks --benchmark_format=json | tee android-results.json
```

--------------------------------

### Install cquery or ccls via Homebrew

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Setting-up-the-Engine-development-environment.md

Installs the cquery or ccls language server on macOS using Homebrew. These tools provide advanced IDE features for C/C++/Objective-C development.

```shell
brew install cquery
# or
brew install ccls
```

--------------------------------

### Initialize SkiaGoldClient

Source: https://github.com/flutter-team-archive/engine/blob/main/testing/skia_gold_client/README.md

Initializes the SkiaGoldClient with a working directory and authenticates it. Ensure to clean up the temporary directory afterwards.

```dart
import 'dart:io' as io;

import 'package:skia_gold_client/skia_gold_client.dart';

void main() async {
  // Create a temporary working directory.
  final io.Directory tmpDirectory = io.Directory.systemTemp.createTempSync('skia_gold_wd');
  try {
    final SkiaGoldClient client = SkiaGoldClient(tmpDirectory);
    await client.auth();
    // ...
  } finally {
    tmpDirectory.deleteSync(recursive: true);
  }
}
```

--------------------------------

### Initialize Google Cloud Project

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/rbe/rbe.md

Initialize the gcloud SDK with the correct project ID for RBE. Ensure the gcloud tool is on your PATH.

```bash
gcloud init --project flutter-rbe-prod
```

--------------------------------

### Prepare Build Files and Build Binary

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/fuchsia/dart_runner/tests/startup_integration_test/dart_aot_runner/README.md

Configures the build using GN and compiles the necessary binaries for the Dart AOT runner integration tests.

```bash
$ENGINE_DIR/flutter/tools/gn --fuchsia --no-lto --runtime-mode=profile
ninja -C $ENGINE_DIR/out/fuchsia_profile_x64 flutter/shell/platform/fuchsia fuchsia_tests
```

--------------------------------

### Run Android Tests

Source: https://github.com/flutter-team-archive/engine/blob/main/testing/scenario_app/android/README.md

Execute the test runner script to install and run tests on a connected device or emulator. This script handles test app installation, test execution, and result reporting.

```sh
dart ./testing/scenario_app/bin/run_android_tests.dart
```

--------------------------------

### Generate Fuchsia Build Files

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Use the 'gn' tool to generate build files for Fuchsia. Specify '--fuchsia-cpu' for different architectures and '--runtime-mode' for release or profile builds. Omit '--no-lto' to enable link-time optimization.

```bash
./flutter/tools/gn --fuchsia --no-lto
```

--------------------------------

### Download Licenses with Gradle

Source: https://github.com/flutter-team-archive/engine/blob/main/tools/cipd/android_embedding_bundle/README.md

Fetches license information for the project's dependencies.

```bash
gradle downloadLicenses
```

--------------------------------

### Example Gradle Dependency Error

Source: https://github.com/flutter-team-archive/engine/blob/main/testing/scenario_app/android/README.md

This error message indicates that the dependency lockfile is out of date and needs to be updated.

```txt
FAILED: scenario_app/reports/lint-results.xml
vpython3 ../../flutter/testing/rules/run_gradle.py /b/s/w/ir/cache/builder/src/flutter/testing/scenario_app/android lint --no-daemon -Pflutter_jar=/b/s/w/ir/cache/builder/src/out/android_emulator_skia_debug_x64/flutter.jar -Pout_dir=/b/s/w/ir/cache/builder/src/out/android_emulator_skia_debug_x64/scenario_app --project-cache-dir=/b/s/w/ir/cache/builder/src/out/android_emulator_skia_debug_x64/scenario_app/.gradle --gradle-user-home=/b/s/w/ir/cache/builder/src/out/android_emulator_skia_debug_x64/scenario_app/.gradle

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:checkDebugAarMetadata'.
> Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
   > Resolved 'org.hamcrest:hamcrest-core:1.3' which is not part of the dependency lock state
   > Resolved 'com.google.code.findbugs:jsr305:2.0.2' which is not part of the dependency lock state
```

--------------------------------

### Build Unoptimized Binary (macOS/Linux)

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Compile a desktop unoptimized binary using ninja. If --unoptimized was not used, build with 'ninja -C out/host_debug'.

```bash
ninja -C out/host_debug_unopt
```

--------------------------------

### Testing with MockGLES

Source: https://github.com/flutter-team-archive/engine/blob/main/impeller/renderer/backend/gles/test/README.md

Demonstrates how to create a mock GLES implementation, interact with its procedure table, and inspect captured calls for testing.

```cc
TEST(MockGLES, Example) {
  // Creates a mock GLES implementation and sets it as the current one.
  auto mock_gles = MockGLES::Init();
  auto& gl = mock_gles->GetProcTable();

  // Call the proc table methods as usual, or pass the proc table to a class
  // that needs it.
  gl.PushDebugGroupKHR(GL_DEBUG_SOURCE_APPLICATION_KHR, 0, -1, "test");
  gl.PopDebugGroupKHR();

  // Method names are recorded and can be inspected.
  //
  // Note that many built-ins, like glGetString, are not recorded (otherwise the // logs would be much bigger and less useful).
  auto calls = mock_gles->GetCapturedCalls();
  EXPECT_EQ(calls, std::vector<std::string>(
                       {"PushDebugGroupKHR", "PopDebugGroupKHR"}));
}
```

--------------------------------

### Build iOS Display List Benchmarks

Source: https://github.com/flutter-team-archive/engine/blob/main/testing/benchmark/README_displaylist.md

Build the dylib containing the benchmarking code for iOS. This is not built by default and requires specifying the target manually.

```bash
$ ninja -C out/ios_profile ios_display_list_benchmarks
```

--------------------------------

### Update VSCode Workspace Configuration

Source: https://github.com/flutter-team-archive/engine/blob/main/tools/vscode_workspace/README.md

Run this script to update the `//engine.code-workspace` file. Ensure necessary tools are installed.

```shell
./refresh.sh
```

--------------------------------

### Build Binary (Windows)

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Compile the engine using ninja, specifying the output directory. For non-debug configurations, you can build gen_snapshot specifically.

```bash
ninja -C .\out\<dir created by previous step>
```

```bash
ninja -C .\out\<dir created by previous step> gen_snapshot
```

--------------------------------

### Prepare Build Files with gn

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Generate build files using the 'gn' tool with unoptimized and full Dart SDK flags. This prepares the engine for compilation.

```bash
python .\flutter\tools\gn --unoptimized --full-dart-sdk
```

--------------------------------

### Update Chrome for Testing Version

Source: https://github.com/flutter-team-archive/engine/blob/main/lib/web_ui/README.md

Manually update the Chrome for Testing version in `dev/package_lock.yaml`. Ensure `depot_tools` is installed and you are authenticated with CIPD.

```yaml
- "chrome"
  version: "118.0.5993.70"
```

--------------------------------

### Get Display Refresh Rate

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/Engine-specific-Service-Protocol-extensions.md

Retrieves the display refresh rate of the device running the Flutter view. Requires a viewId as an argument.

```text
viewId = _flutterView/0x15bf057f8
```

```json
{
  "type": "DisplayRefreshRate",
  "fps": 60.0
}
```

--------------------------------

### Prepare Android Build Files with gn

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Use the `gn` tool to configure build files for Android targets. Specify CPU architecture and optimization level as needed.

```bash
./flutter/tools/gn --android --unoptimized
```

```bash
./flutter/tools/gn --android --android-cpu arm64 --unoptimized
```

```bash
./flutter/tools/gn --android --android-cpu x86 --unoptimized
```

```bash
./flutter/tools/gn --android --android-cpu x64 --unoptimized
```

```bash
./flutter/tools/gn --unoptimized
```

```bash
./flutter/tools/gn --unoptimized --mac-cpu arm64
```

--------------------------------

### Run Impeller Golden Tests

Source: https://github.com/flutter-team-archive/engine/blob/main/impeller/golden_tests/README.md

Example invocation for running the Impeller golden tests. This script is used to generate golden images for testing.

```sh
./run_tests.py --variant="host_debug_unopt_arm64" --type="impeller-golden"
```

--------------------------------

### Sample Sanitizer Suppressions Output

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/Using-Sanitizers-with-the-Flutter-Engine.md

This is an example of the output you might see after sourcing the sanitizer suppressions script, indicating which suppression files are being used.

```text
Using Thread Sanitizer suppressions in ./flutter/testing/tsan_suppressions.txt
Using Leak Sanitizer suppressions in ./flutter/testing/lsan_suppressions.txt
```

--------------------------------

### Build Fuchsia OS

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/fuchsia/flutter/tests/integration/touch-input/README.md

These commands are used to configure and build the Fuchsia operating system for the terminal environment. Ensure you have the necessary build tools installed.

```shell
fx set terminal.qemu-x64 && fx build
```

--------------------------------

### DDS Command-Line Interface Help

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/Using-the-Dart-Development-Service-(DDS)-and-Flutter-DevTools-with-a-custom-Flutter-Engine-Embedding.md

Displays the available options for configuring the Dart Development Service when using the `dart development-service` command. The `--vm-service-uri` is mandatory.

```bash
Start Dart's development service.

Usage: dart [vm-options] development-service [arguments]
-h, --help                                 Print this usage information.
    --vm-service-uri=<uri> (mandatory)     The VM service URI DDS will connect to.
    --bind-address=<address>               The address DDS should bind to.
                                           (defaults to "localhost")
    --bind-port=<port>                     The port DDS should be served on.
                                           (defaults to "0")
    --[no-]disable-service-auth-codes      Disables authentication codes.
    --[no-]serve-devtools                  If provided, DDS will serve DevTools. If not specified, "--devtools-server-address" is ignored.
    --devtools-server-address              Redirect to an existing DevTools server. Ignored if "--serve-devtools" is not specified.
    --[no-]enable-service-port-fallback    Bind to a random port if DDS fails to bind to the provided port.
    --cached-user-tags                     A set of UserTag names used to determine which CPU samples are cached by DDS.
    --google3-workspace-root               Sets the Google3 workspace root used for google3:// URI resolution.

Run "dart help" to see global options.
```

--------------------------------

### Initialize LocaleKeymap Mapping

Source: https://github.com/flutter-team-archive/engine/blob/main/third_party/web_locale_keymap/README.md

Instantiate the `LocaleKeymap` with the appropriate platform-specific mapping. Use `.win()`, `.darwin()`, or `.linux()` based on the target operating system.

```dart
import 'package:web_locale_keymap/web_locale_keymap.dart' as locale_keymap;

final locale_keymap.LocaleKeymap mapping = 
    locale_keymap.LocaleKeymap.win(); // Or .darwin() or .linux()
```

--------------------------------

### Enable Log Output in Tests

Source: https://github.com/flutter-team-archive/engine/blob/main/shell/platform/android/test/README.md

To see log output from your tests in the console, import `org.robolectric.shadows.ShadowLog` and set `ShadowLog.stream = System.out;` in your test or setup method.

```java
import org.robolectric.shadows.ShadowLog;

// In your test or setup method:
ShadowLog.stream = System.out;
```

--------------------------------

### Specify Android Debug Unoptimized Build for clang-tidy

Source: https://github.com/flutter-team-archive/engine/blob/main/tools/clang_tidy/README.md

Example of running clang-tidy specifically on the `android_debug_unopt` build variant. This demonstrates the usage of the `--target-variant` flag.

```shell
dart ./tools/clang_tidy/bin/main.dart --target-variant android_debug_unopt
```

--------------------------------

### Update .ci.yaml for Apple Signing

Source: https://github.com/flutter-team-archive/engine/blob/main/tools/cipd/mobileprovision/README.md

Shows the before and after configuration for migrating 'apple_signing' steps in .ci.yaml to use a new version tag.

```yaml
Before: {"dependency": "apple_signing", "version": "version:to_2024"}
After: {"dependency": "apple_signing", "version": "version:to_2025"}
```

--------------------------------

### Create Native Activity APK

Source: https://github.com/flutter-team-archive/engine/blob/main/testing/android/native_activity/README.md

Use `native_activity_apk` to build an APK for your executable. Specify the `apk_name`, `testonly` status, source files, and dependencies.

```gn
native_activity_apk("apk_unittests") {
  apk_name = "toolkit_unittests"

  testonly = true

  sources = [ "toolkit_android_unittests.cc" ]

  deps = [
    ":unittests_lib",
    "//flutter/testing/android/native_activity:gtest_activity",
  ]
}
```

--------------------------------

### Build specific test target with Ninja

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/testing/Testing-the-engine.md

Manually invoke the ninja command if the `run_tests.py` script fails to build the test library, for example, if `libios_test_flutter.dylib` is missing.

```bash
ninja -C $FLUTTER_ENGINE/out/ios_debug_sim_unopt_arm64 ios_test_flutter
```

--------------------------------

### Configure Fuchsia Dependencies

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Update the .gclient file to enable downloading Fuchsia dependencies and running the emulator. 'run_fuchsia_emu' can be omitted if local tests are not required.

```python
solutions = [
  {
    # ...
    "custom_vars": {
      "download_fuchsia_deps": True,
      "run_fuchsia_emu": True,
    },
  },
]
```

--------------------------------

### Configure Gclient Variables

Source: https://github.com/flutter-team-archive/engine/blob/main/ci/builders/README.md

Sets variables for the gclient sync operation, often used to manage dependencies. This example disables downloading Android SDK dependencies.

```json
"gclient_variables": {
   "download_android_deps": false
}
```

--------------------------------

### Configure Visual Studio (Windows)

Source: https://github.com/flutter-team-archive/engine/blob/main/docs/contributing/Compiling-the-engine.md

Set environment variables to point depot tools at your Visual Studio installation. Ensure Python 2.7 is prioritized in your Path.

```powershell
DEPOT_TOOLS_WIN_TOOLCHAIN=0
GYP_MSVS_OVERRIDE_PATH="C:\Program Files (x86)\Microsoft Visual Studio\2019\Community" # (or your location for Visual Studio)
WINDOWSSDKDIR="C:\Program Files (x86)\Windows Kits\10" # (or your location for Windows Kits)
```