nexusmods-app: run tests in a passthru (#421459)

pkgs/by-name/ne/nexusmods-app/package.nix

@@ -118,7 +118,12 @@ buildDotnetModule (finalAttrs: {
     "--property:DefineConstants=${lib.strings.concatStringsSep "%3B" constants}"
   ];
 
-  doCheck = true;
+  # Avoid running `dotnet test` in the main package:
+  # - The test-suite is slow
+  # - Some tests fail intermittently
+  # - The package is often uncached; especially the unfree variant
+  # - We can enable tests in a `passthru.tests` override
+  doCheck = false;
 
   dotnetTestFlags = [
     "--environment=USER=nobody"
@@ -174,6 +179,14 @@ buildDotnetModule (finalAttrs: {
     runHook postInstallCheck
   '';
 
+  passthru.tests = {
+    # Build the package and run `dotnet test`
+    app = finalAttrs.finalPackage.overrideAttrs {
+      pname = "${finalAttrs.pname}-tested";
+      doCheck = true;
+    };
+  };
+
   passthru.updateScript = nix-update-script { };
 
   meta = {