nix: introduce tests

Introduce set of tests based on NixOS test framework.

.github/workflows/build.yml

@@ -101,3 +101,20 @@ jobs:
       - name: Build yandex-music without flakes binaries
         run: nix build --impure .#yandex-music-noflakes
 
+  nix-test:
+    runs-on: ubuntu-latest
+    env:
+      NIXPKGS_ALLOW_UNFREE: 1
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ (inputs.ref || '') }}
+
+      - name: Install nix
+        uses: cachix/install-nix-action@v22
+
+      - uses: DeterminateSystems/magic-nix-cache-action@v2
+
+      - name: Run NixOS tests
+        run: nix build --impure .#tests

README.md

@@ -40,6 +40,7 @@ Native YandexMusic client for Linux. Built using repacking of Windows client (El
       - [Run with flakes](#run-with-flakes)
       - [Run old style](#run-old-style)
       - [Install to NixOS](#install-to-nixos)
+   - [NixOS tests](#nixos-tests)
 - [Star History](#star-history)
 
 
@@ -337,6 +338,40 @@ nix-build --expr '(import <nixpkgs> {}).callPackage ./nix {}'
     programs.yandex-music.enable = true;
     programs.yandex-music.tray.enable = true; # to enable tray support
     ```
+#### NixOS tests
+
+This project uses [NixOS Testing
+framework](https://nixos.org/manual/nixos/stable/index.html#sec-nixos-tests) to
+perform generic run-tests of NixOS module and built app.
+
+It runs automatically by github actions, but you may want to perform tests on
+your own PC.
+
+The root flake exports package `tests` with symlinks to artefact of all tests.
+
+So you can run them by
+
+```bash
+nix build .#tests
+```
+
+Each test is complete qemu VM with NixOS onboard and configured yandex-music
+application. The test performs withing the result package building inside nix
+sandbox. The simple python script perform all the basic checks. The tests are
+differs between each other by configuration options to yandex-music module. You
+can see all of them [here](./nix/test.nix#L46).
+
+You can run each test separately as sub-attr of `tests` package, e.g:
+
+```bash
+nix build .#tests.trayMonoWhite
+```
+
+You may want to see logs of each test (even failed) with `nix log` command, e.g:
+
+```bash
+nix log .#tests.customTitleBar
+```
 
 ## Star History
 

flake.nix

@@ -21,12 +21,17 @@
         pkgs.callPackage ./nix {
           inherit ymExe;
         };
-      modules = isHm: rec {
+      modules =
-        yandex-music = {
+        {
-          imports = [ (import ./nix/module.nix { inherit isHm yandex-music-with; }) ];
+          isHm ? false,
+          isTest ? false,
+        }:
+        rec {
+          yandex-music = {
+            imports = [ (import ./nix/module.nix { inherit isHm isTest yandex-music-with; }) ];
+          };
+          default = yandex-music;
         };
-        default = yandex-music;
-      };
     in
     flake-utils.lib.eachDefaultSystem (
       system:
@@ -38,13 +43,17 @@
           yandex-music = yandex-music-with pkgs;
           yandex-music-noflakes = pkgs.callPackage ./nix { };
           default = yandex-music;
+          tests = pkgs.callPackage ./nix/test.nix {
+            nixosModule = (modules { isTest = true; }).yandex-music;
+            inherit yandex-music-with;
+          };
         };
         formatter = pkgs.nixfmt-rfc-style;
       }
     )
     // {
-      nixosModules = modules false;
+      nixosModules = modules { };
-      homeManagerModules = modules true;
+      homeManagerModules = modules { isHm = true; };
 
       nixosModule = self.nixosModules.default;
     };

nix/module.nix

@@ -1,6 +1,7 @@
 {
   yandex-music-with,
   isHm ? false,
+  isTest ? false,
 }:
 {
   lib,
@@ -13,14 +14,18 @@ let
 
 in
 {
+  /*
+    The NixOS test framework disallow to extend `nixpkgs.overlays` configuration
+    option, so we make it here conditionally.
+  */
   imports = [
-    {
+    (lib.mkIf (!isTest) {
       nixpkgs.overlays = [
         (final: prev: {
           yandex-music = yandex-music-with prev;
         })
       ];
-    }
+    })
   ];
 
   options = {

nix/test-suite.nix

@@ -0,0 +1,62 @@
+/*
+  This test suite uses nixos common x11 and user-account test configurations.
+  Those configurations use auto-login to ice-wm desktop manager.
+  This test configuration enables yandex-music application, launches it and
+  check for window existence. Additionally it takes screenshot after successful
+  launch to allow to validate state manually. The result may miss the content
+  inside window because of lack of GPU support.
+
+  TODO(Shvedov): We should to perform automatic checks of screen state.
+*/
+{
+  testers,
+  path,
+
+  # The yandex-music module
+  nixosModule,
+  # The extra configuration
+  configuration ? { },
+  # The extra code of test script
+  extraTestScript ? "",
+  # The name of test
+  name ? "yandex-music-test",
+}:
+testers.runNixOSTest {
+  inherit name;
+  nodes.machine =
+    let
+      tests = "${path}/nixos/tests/common/";
+      user = "alice";
+    in
+    {
+      imports = [
+        nixosModule
+        "${tests}/x11.nix"
+        "${tests}/user-account.nix"
+        configuration
+      ];
+      test-support.displayManager.auto.user = user;
+      programs.yandex-music.enable = true;
+    };
+
+  testScript =
+    ''
+      # We have to execute command with su beckause all commands performs under
+      # the root user.
+      def mk_command(command, tail = "", fork = False):
+        if fork:
+          tail = f"{tail} >&2 &"
+        return f"su -c '{command}' - alice {tail}"
+
+      machine.wait_for_x()
+      machine.execute(mk_command("yandex-music", fork = True))
+
+      check_command = mk_command('xwininfo -root -tree', tail = "| grep 'Яндекс Музыка'")
+
+      machine.wait_until_succeeds(check_command, 120)
+      machine.sleep(40)
+      machine.succeed(check_command)
+      machine.screenshot("screen")
+    ''
+    + extraTestScript;
+}

nix/test.nix

@@ -0,0 +1,81 @@
+/*
+  This is set of tests of yandex-music application. The main purpose of this
+  test is to check the NixOS module for yandex-music and whether its runs
+  successfully with such configuration.
+*/
+{
+  pkgs,
+  yandex-music-with,
+  nixosModule,
+  linkFarm,
+  lib,
+}:
+let
+  # Extend packages with our package to overcome the limitation of nixOSTest
+  # modules regarding the overlays.
+  pkgs' = pkgs.extend (cur: prev: { yandex-music = yandex-music-with prev; });
+  removeNameAttr = attrs: lib.removeAttrs attrs [ "name" ];
+  test-suite =
+    {
+      name ? "yandex-music-test",
+      ...
+    }@configuration:
+    pkgs'.callPackage ./test-suite.nix {
+      inherit nixosModule name;
+      configuration = removeNameAttr configuration;
+    };
+  yandex-music-config = cfg: {
+    programs.yandex-music = cfg;
+  };
+  yandex-music-test-suite =
+    {
+      name,
+      ...
+    }@cfg:
+    test-suite (
+      (yandex-music-config (removeNameAttr cfg))
+      // {
+        name = "yandex-music-test-${name}";
+      }
+    );
+  /*
+    This is set of similar tests with slightly different configuration options
+    for yandex-music module. All they will be joined together to package with
+    symlinks to all results.
+  */
+  tests = {
+    base = test-suite { };
+    trayDefault = yandex-music-test-suite {
+      tray.enable = true;
+      name = "tray-default";
+    };
+    trayAlways = yandex-music-test-suite {
+      tray.enable = true;
+      tray.always = true;
+      name = "tray-always";
+    };
+    trayMonoBlack = yandex-music-test-suite {
+      tray.enable = true;
+      tray.style = 2;
+      name = "tray-mono-black";
+    };
+    trayMonoWhite = yandex-music-test-suite {
+      tray.enable = true;
+      tray.style = 3;
+      name = "tray-mono-white";
+    };
+    devTools = yandex-music-test-suite {
+      devTools.enable = true;
+      name = "dev-tools";
+    };
+    customTitleBar = yandex-music-test-suite {
+      customTitleBar.enable = true;
+      name = "custom-title-bar";
+    };
+    animatiosFpsZero = yandex-music-test-suite {
+      vibeAnimationMaxFps = 0;
+      name = "animation-fps-zero";
+    };
+  };
+in
+(linkFarm "yandex-music-test-all" tests) // tests