inkscape: add unit test for ps2pdf plugin

to prevent future regressen add a smal test,
to check if ps2pdf plugin is working
by createing a .ps / .eps file and converting it back to svg

(cherry picked from commit fae8ec30ea)

pkgs/applications/graphics/inkscape/default.nix

@@ -3,6 +3,7 @@
 , boehmgc
 , boost
 , cairo
+, callPackage
 , cmake
 , desktopToDarwinBundle
 , fetchurl
@@ -172,6 +173,8 @@ stdenv.mkDerivation rec {
     done
   '';
 
+  passthru.tests.ps2pdf-plugin = callPackage ./test-ps2pdf-plugin.nix { };
+
   meta = with lib; {
     description = "Vector graphics editor";
     homepage = "https://www.inkscape.org";

pkgs/applications/graphics/inkscape/test-ps2pdf-plugin.nix

@@ -0,0 +1,27 @@
+{ inkscape, runCommand, writeTextFile }:
+
+let
+  svg_file = writeTextFile {
+    name = "test.svg";
+    text = ''
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="50" height="50" version="1.1">
+  <ellipse cx="1" cy="1" rx="1" ry="1" />
+</svg>'';
+  };
+in
+runCommand "inkscape-test-eps"
+{
+  nativeBuildInputs = [ inkscape ];
+} ''
+  echo ps test
+  inkscape ${svg_file} --export-type=ps -o test.ps
+  inkscape test.ps -o test.ps.svg
+
+  echo eps test
+  inkscape ${svg_file} --export-type=eps -o test.eps
+  inkscape test.eps -o test.eps.svg
+
+  # inkscape does not return an error code, only does not create files
+  [[ -f test.ps.svg && -f test.eps.svg ]] && touch $out
+''