Revert "vengi-tools: remove failing roundtrip test"

This reverts commit 50dae31a14.

pkgs/applications/graphics/vengi-tools/default.nix

@@ -87,9 +87,7 @@ stdenv.mkDerivation rec {
   '';
 
   passthru.tests = {
-    # There used to be a roundtrip test here, but it started failing on 0.0.17
-    # Relevant upstream ticket:
-    # https://github.com/mgerhardy/vengi/issues/113
+    voxconvert-roundtrip = callPackage ./test-voxconvert-roundtrip.nix {};
     voxconvert-all-formats = callPackage ./test-voxconvert-all-formats.nix {};
     run-voxedit = nixosTests.vengi-tools;
   };

pkgs/applications/graphics/vengi-tools/test-voxconvert-roundtrip.nix

@@ -0,0 +1,15 @@
+{ stdenv
+, vengi-tools
+}:
+
+stdenv.mkDerivation {
+  name = "vengi-tools-test-voxconvert-roundtrip";
+  meta.timeout = 10;
+  buildCommand = ''
+    ${vengi-tools}/bin/vengi-voxconvert --input ${vengi-tools}/share/vengi-voxedit/chr_knight.qb --output chr_knight.vox
+    ${vengi-tools}/bin/vengi-voxconvert --input chr_knight.vox --output chr_knight.qb
+    ${vengi-tools}/bin/vengi-voxconvert --input chr_knight.qb --output chr_knight1.vox
+    diff chr_knight.vox chr_knight1.vox
+    touch $out
+  '';
+}