Add testing with umockdev (#2)

* add mocked device tests

* update readme

* remove dev/null

* fix test build

.github/workflows/test.yml

@@ -0,0 +1,28 @@
+name: UmockdevTest
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Install umockdev
+      run: sudo apt-get update -y && sudo apt-get install -y umockdev
+
+    - name: Set up Go
+      uses: actions/setup-go@v4
+      with:
+        go-version: '1.20'
+
+    - name: Build command line tool
+      run: go build -v -o /tmp/usbrelay cmd/usbrelay/main.go
+
+    - name: Run umockdev tests
+      run: cd test && chmod +x test.sh && ./test.sh

README.md

@@ -92,6 +92,16 @@ udev rules:
    - `sudo udevadm control --reload-rules && sudo udevadm trigger`
 4. Make sure to unplug and replug the USB device!
 
+## Testing
+
+Testing is done via a mocked virtual USB device with [umockdev](https://github.com/martinpitt/umockdev).
+
+A 4 channel device was used to record the USB communication with [wireshark](https://www.wireshark.org/) and `usbmon` 
+while executing the command line tool.
+
+Each command's communication is stored in a separate `pcap` file in the test directory and replayed for the command line
+tool with `umockdev-run` using the actual device's stored sysfs device and udev properties.
+
 ## Credits
 
 This package is an amalgamation of a few people's previous work: