pipewire: add testing

This adds two tests. One is for whether the paths used by the module are
present, while the other is for testing functionality of PipeWire
itself. This is done with the recent addition of installed tests by
upstream.

pkgs/development/libraries/pipewire/default.nix

@@ -24,6 +24,8 @@
 , vulkan-loader
 , libpulseaudio
 , makeFontsConf
+, callPackage
+, nixosTests
 , ofonoSupport ? true
 , nativeHspSupport ? true
 }:
@@ -37,7 +39,7 @@ stdenv.mkDerivation rec {
   pname = "pipewire";
   version = "0.3.9";
 
-  outputs = [ "out" "lib" "dev" "doc" ];
+  outputs = [ "out" "lib" "dev" "doc" "installedTests" ];
 
   src = fetchFromGitLab {
     domain = "gitlab.freedesktop.org";
@@ -50,8 +52,14 @@ stdenv.mkDerivation rec {
   patches = [
     # Break up a dependency cycle between outputs.
     ./alsa-profiles-use-libdir.patch
+    # Move installed tests into their own output.
+    ./installed-tests-path.patch
   ];
 
+  postPatch = ''
+    substituteInPlace meson.build --subst-var-by installed_tests_dir "$installedTests"
+  '';
+
   nativeBuildInputs = [
     doxygen
     graphviz
@@ -86,6 +94,7 @@ stdenv.mkDerivation rec {
     "-Dman=false" # we don't have xmltoman
     "-Dgstreamer=true"
     "-Dudevrulesdir=lib/udev/rules.d"
+    "-Dinstalled_tests=true"
   ] ++ stdenv.lib.optional nativeHspSupport "-Dbluez5-backend-native=true"
   ++ stdenv.lib.optional ofonoSupport "-Dbluez5-backend-ofono=true";
 
@@ -93,6 +102,23 @@ stdenv.mkDerivation rec {
 
   doCheck = true;
 
+  passthru.tests = {
+    installedTests = nixosTests.installed-tests.pipewire;
+
+    # This ensures that all the paths used by the NixOS module are found.
+    test-paths = callPackage ./test-paths.nix {
+      paths-out = [
+        "share/alsa/alsa.conf.d/50-pipewire.conf"
+      ];
+      paths-lib = [
+        "lib/alsa-lib/libasound_module_pcm_pipewire.so"
+        "lib/pipewire-0.3/jack"
+        "lib/pipewire-0.3/pulse"
+        "share/alsa-card-profile/mixer"
+      ];
+    };
+  };
+
   meta = with stdenv.lib; {
     description = "Server and user space API to deal with multimedia pipelines";
     homepage = "https://pipewire.org/";