fedifetcher: check if all requirements are there

Until we have a proper wheel, we can check with that if all deps are
there.

nanos/FediFetcher#177

pkgs/tools/misc/fedifetcher/default.nix

@@ -1,4 +1,4 @@
-{ lib, fetchFromGitHub, python3 }:
+{ lib, fetchFromGitHub, python3, stdenv }:
 
 python3.pkgs.buildPythonApplication rec {
   pname = "fedifetcher";
@@ -26,6 +26,14 @@ python3.pkgs.buildPythonApplication rec {
     runHook postInstall
   '';
 
+  checkPhase = lib.optionalString (stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
+    runHook preCheck
+
+    $out/bin/fedifetcher --help>/dev/null
+
+    runHook postCheck
+  '';
+
   meta = with lib; {
     description = "A tool for Mastodon that automatically fetches missing replies and posts from other fediverse instances";
     longDescription = ''