croc: add passthru.tests

pkgs/tools/networking/croc/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, buildGoModule, fetchFromGitHub }:
+{ stdenv, buildGoModule, fetchFromGitHub, callPackage}:
 
 buildGoModule rec {
   pname = "croc";
@@ -17,6 +17,11 @@ buildGoModule rec {
 
   subPackages = [ "." ];
 
+  passthru = {
+    tests = {
+      local-relay = callPackage ./test-local-relay.nix {};
+    };
+  };
   meta = with stdenv.lib; {
     description =
       "Easily and securely send things from one computer to another";

pkgs/tools/networking/croc/test-local-relay.nix

@@ -0,0 +1,20 @@
+{ stdenv, croc }:
+
+stdenv.mkDerivation {
+  name = "croc-test-local-relay";
+  meta.timeout = 300;
+  buildCommand = ''
+          HOME=$(mktemp -d)
+          # start a local relay
+          ${croc}/bin/croc relay --ports 11111,11112 &
+          # start sender in background
+          MSG="See you later, alligator!"
+          ${croc}/bin/croc --relay localhost:11111 send --code correct-horse-battery-staple --text "$MSG" &
+          # wait for things to settle
+          sleep 1
+          # receive
+          MSG2=$(${croc}/bin/croc --relay localhost:11111 --yes correct-horse-battery-staple)
+          # compare
+          [ "$MSG" = "$MSG2" ] && touch $out
+  '';
+}