Run an end-to-end test

This guide provides instructions on how to run an end-to-end test for testing a Fuchsia product.

This guide uses the Fuchsia emulator (FEMU) to emulate a device that runs Fuchsia. As for the end-to-end test, the guide uses the screen_is_not_black end-to-end test.

The screen_is_not_black end-to-end test reboots a device under test (DUT), waits 100 seconds, and takes a snapshot of the device’s screen. If the snapshot image is not a black screen, the test concludes that Fuchsia is successfully up and running on the device after reboot.

To run this end-to-end test, the steps are:

Prerequisites.
Build a Fuchsia image to include the end-to-end test.
Start the emulator with the Fuchsia image.
Run the end-to-end test.

Also, to run any end-to-end test, see the Appendices section.

1. Prerequisites

This guide requires that you've completed the following guides:

2. Build a Fuchsia image to include the end-to-end test

Before you can run the screen_is_not_black end-to-end test, you first need to build your Fuchsia image to include the test in the build artifacts:

To add the end-to-end test, run the fx set command with the following --with option:
```
fx set workstation.qemu-x64 --with //src/tests/end_to_end/screen_is_not_black
```
//src/tests/end_to_end/screen_is_not_black is a test directory in the Fuchsia source tree. The BUILD.gn file in this directory defines the screen_is_not_black target to include the screen_is_not_black end-to-end test in the build artifacts.
Build your Fuchsia image:
```
fx build
```
When the fx build command completes, the build artifacts now include the screen_is_not_black end-to-end test, which you can run from your host machine.

3. Start the emulator with the Fuchsia image

Start the emulator with your Fuchsia image and run a package repository server:

Configure an IPv6 network for the emulator:

Note: This has to be completed once per machine.
```
sudo ip tuntap add dev qemu mode tap user $USER && sudo ip link set qemu up
```
Configure the upscript:

Note: If your machine is behind a firewall, you may need to apply some additional configuration to allow the emulator to access the network. This is typically accomplished by running an "upscript", which sets up the interfaces and firewall access rules for the current process. If you're on a corporate network, check with your internal networking team to see if they have an existing upscript for you to use. If you're not behind a firewall, there's still some configuration needed to enable tun/tap networking. The example upscript at FUCHSIA_ROOT/scripts/start-unsecure-internet.sh should work for the majority of non-corporate users.
```
ffx config set emu.upscript PATH_TO_UPSCRIPT
```
Replace the following:
- PATH_TO_UPSCRIPT: The path to a FEMU network setup script; for example, ~/fuchsia/scripts/start-unsecure-internet.sh.
Start the package server
```
fx serve
```
Start the emulator:
```
ffx emu start --net tap
```
When startup is complete, the emulator prints the following message and opens a shell prompt:
```
Logging to "$HOME/.local/share/Fuchsia/ffx/emu/instances/fuchsia-emulator/emulator.log"
Waiting for Fuchsia to start (up to 60 seconds)........Emulator is ready.
```
1. The --net flag requires a value to indicate which kind of networking to implement. --net has the following possible values:
  - tap: Attaches a Tun/Tap interface.
  - user: Sets up mapped ports through SLiRP.
  - none: Disables networking.
  - auto: Checks the host system's capabilities and selects tap if it is available or user if a tap interface is unavailable. auto is the default.
auto is the default if the flag is not specified on the command line. The upscript is automatically executed only if the user selects tap mode.

If auto is used, the launcher checks for a tap interface on the device. If it finds a tap interface, it uses tap mode; otherwise it uses user mode.

Run the fx set-device command and select fuchsia-emulator (the emulator's default device name) to be your device, for example:

$ fx set-device
ERROR: Multiple devices found, please pick one from the list:
1) fuchsia-4407-0bb4-d0eb
2) fuchsia-emulator
#? 2
New default device: fuchsia-emulator

4. Run the end-to-end test

Run the screen_is_not_black end-to-end test:

fx test --e2e screen_is_not_black

When the test passes, this command prints output similar to the following:

Saw a screen that is not black; waiting for 0:00:59.924543 now.

...

[FINE]: Running over ssh: killall sl4f.cmx
01:46 +1: All tests passed!

Appendices

Run any end-to-end test

Use the fx test --e2e command to run an end-to-end test from your host machine:

fx test --e2e <TEST_NAME>

Some product configurations may include a set of end-to-end tests by default (see Examine product configuration files). However, if you want to run an end-to-end test that is not part of your product configuration, configure your Fuchsia image to include the specific test:

fx set <PRODUCT>.<BOARD> --with <TEST_DIRECTORY>:<TARGET>

For example, the following commands configure and build your Fuchsia image with all the end-to-end tests in the //src/tests/end_to_end/perf test directory:

$ fx set workstation.qemu-x64 --with //src/tests/end_to_end/perf:test
$ fx build

For the list of all available end-to-end tests in the Fuchsia repository, see the //src/tests/end_to_end directory.

Examine product configuration files

To find out which end-to-end tests are included in a specific product configuration, examine product configuration files (.gni) in the Fuchsia repository's //products directory.

The following example shows the product configurations files in the //products directory:

~/fuchsia/products$ ls *.gni
bringup.gni  core.gni  terminal.gni  workstation.gni

To see the list of all available product configurations, you can run the following command:

fx list-products

Among these product configurations, terminal and workstation include end-to-end tests by default. The following example shows the end-to-end tests included in terminal.gni:

cache_package_labels += [
  ...
  "//src/tests/end_to_end/bundles:end_to_end_deps",
  "//src/tests/end_to_end/bundles:terminal_end_to_end_deps",
]

...

universe_package_labels += [
  "//src/tests/end_to_end/screen_is_not_black",
  "//src/tests/end_to_end/sl4f:test",
  "//src/tests/end_to_end/perf:test",
  ...
]