supercollider: add sc3-plugins test

pkgs/development/interpreters/supercollider/default.nix

@@ -2,6 +2,8 @@
 , pkg-config, alsa-lib, libjack2, libsndfile, fftw
 , curl, gcc, libXt, qtbase, qttools, qtwebengine
 , readline, qtwebsockets, useSCEL ? false, emacs
+, supercollider-with-plugins, supercolliderPlugins
+, writeText, runCommand
 }:
 
 mkDerivation rec {
@@ -31,6 +33,26 @@ mkDerivation rec {
     "-DSC_EL=${if useSCEL then "ON" else "OFF"}"
   ];
 
+  passthru.tests = {
+    # test to make sure sclang runs and included plugins are successfully found
+    sclang-sc3-plugins = let
+      supercollider-with-test-plugins = supercollider-with-plugins.override {
+        plugins = with supercolliderPlugins; [ sc3-plugins ];
+      };
+      testsc = writeText "test.sc" ''
+        var err = 0;
+        try {
+        MdaPiano.name.postln;
+        } {
+        err = 1;
+        };
+        err.exit;
+      '';
+    in runCommand "sclang-sc3-plugins-test" {} ''
+      timeout 60s env XDG_CONFIG_HOME="$(mktemp -d)" QT_QPA_PLATFORM=minimal ${supercollider-with-test-plugins}/bin/sclang ${testsc} >$out
+    '';
+  };
+
   meta = with lib; {
     description = "Programming language for real time audio synthesis";
     homepage = "https://supercollider.github.io";