Introduction

WLAN Hardware Simulator, or hw-sim, is a framework used to simulate a Fuchsia compatible WLAN device, its corresponding vendor driver and the radio environment it is in. It is mostly used to perform integration tests that involve some interaction between the system and the components mentioned above.

Run tests locally

The most convenient way to run this test locally is to run it in a QEMU instance.

Emulator without network (run test from the emulator command prompt directly)

1. Make sure src/connectivity/wlan:tests is included in with-base so that the driver for the fake wlantap device is loaded in QEMU. For example:

   fx set core.x64 --with-base src/connectivity/wlan:tests,bundles:tools
   

2. Start the emulator instance with

   fx emu
   

   Note: If QEMU is not working, troubleshoot steps can be found here

3. In the QEMU command prompt, run the tests individually in the test directory. For example:

   run-test-component simulate_scan
   

4. Rust tests hides stdout when tests pass. To force displaying stdout, run the test with --nocapture

   run-test-component simulate_scan --nocapture
   

5. After the test finishes, exit QEMU by

   dm shutdown
   

Emulator with network (run test with fx emu from host)

1. Setup QEMU network by following these instructions

   (Googlers: Search “QEMU network setup” for additional steps for your workstation)

2. Same fx set as the previous option

3. Start the emulator with -N to enable network support

   fx emu -N
   

4. From another terminal on the host,

   fx run-test wlan-hw-sim-test
   

5. To force stdout display, pass --nocapture with additional -- so that it does not get parsed by run-test

   fx run-test wlan-hw-sim-test -- --nocapture
   

6. Individual tests can be run with

   fx run-test wlan-hw-sim-test -t simulate_scan
   

Special notes for debugging flakiness in CQ

Enable nested KVM to mimic the behavior of CQ bots

1. Run these commands to enable nested KVM for intel CPU to mimic the behavior of CQ bots. They to be run every time your workstation reboots.

   sudo modprobe -r kvm_intel
   sudo modprobe kvm_intel nested=1
   

2. Verify the result by checking the content of the following file is Y instead of N.

   $ cat /sys/module/kvm_intel/parameters/nested
   Y
   

Run the test repeatedly

Often when debugging flakiness, it is more helpful to run the tests repeatedly. Here is how:

1. Include bundles:tools in your build, so that the seq command is available. The previous example is now

   fx set core.x64 --with-base bundles:tools,src/connectivity/wlan:tests,bundles:tools
   

2. Start an emulator instance

   fx emu -N
   

3. Run the test in the emulator command prompt (not with fx emu)

   for i in $(seq 1 1000); do run-test-component simulate_scan || break; echo success: attempt $i; done;