Add tentative GitHub workflow and OpenCV

Author: Thesola10

.github/workflows/testing.yaml

@@ -0,0 +1,36 @@
+name: "Run end-to-end tests for PaperWM"
+
+on:
+  push:
+    paths:
+      - '*.nix'
+      - '*.js'
+      - 'tests/**'
+
+jobs:
+  run-tests:
+    name: Run unit tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+      - name: Set up Nix
+        uses: cachix/install-nix-action@v20
+      - name: Enable KVM group perms
+        run: |
+          echo 'KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"' | sudo tee /etc/udev/rules.d/99-kvm4all.rules
+          sudo udevadm control --reload-rules
+          sudo udevadm trigger --name-match=kvm
+          sudo tee /etc/nix/nix.conf <<< "extra-system-features = kvm nixos-test"
+      - name: Build test VM
+        run: |
+          nix build .#vm
+      - name: Launch tests
+        run: |
+          for file in tests/features/*.feature
+          do
+            echo "::group::Test ${file##*/}"
+            feat="${file##*/}"
+            nix --extra-experimental-features "nix-command flakes" run .#checks.x86_64-linux.${feat%%.feature}.driver
+            echo "::endgroup::"
+          done

tests/features/environment.py

@@ -2,6 +2,8 @@
 from pathlib import Path
 from behave import fixture, use_fixture
 
+import cv2
+
 class NixOSNamespace(SimpleNamespace):
     ''' Derived version of SimpleNamespace, helps unpack our NixOS test objects
     and add utility functions for commonly used test steps.
@@ -10,6 +12,7 @@ class NixOSNamespace(SimpleNamespace):
     def __init__(self, context):
         self.__dict__.update(**context.config.userdata)
         self._base_dir = Path(context.config.base_dir).parent.resolve()
+        self._context = context
 
     def _gjs_cmdline(self, code):
         SHELL_DBUS = "org.gnome.Shell"
@@ -35,6 +38,13 @@ def wait_for_paperwm(self):
         '''
         return self.machine.wait_until_succeeds(self._gjs_cmdline('paperwm.findModule("tiling").spaces._initDone'))
 
+    def screenshot(self):
+        ''' Take a screenshot and load it as an OpenCV-compatible representation
+        '''
+        filename = f"scenario-{self._context.scenario.line}.png"
+        self.machine.screenshot(filename)
+        return cv2.imread(filename)
+
 @fixture
 def shell(context):
     ''' Wait for PaperWM to start

tests/template.nix

@@ -7,7 +7,7 @@
   name = featureName;
   nodes = { machine = defaultConfig; };
 
-  extraPythonPackages = p: with p; [ behave ];
+  extraPythonPackages = p: with p; [ behave opencv-python ];
 
   skipTypeCheck = true;