added signature zero test

Author: InfiniteSwerve

deku-p/src/core/crypto/tests/alg_intf_tests.ml

@@ -96,6 +96,8 @@ struct
       List.for_all
         (fun (signature, _) -> Signature.equal signature signature)
         (List.flatten signatures)
+
+    let zero = Signature.(to_b58 zero)
   end
 
   module Test_secret_key_data = struct
@@ -217,5 +219,10 @@ struct
       Alcotest.(check' bool)
         ~msg:"signature equality works" ~expected:Tezos_data.equality_signatures
         ~actual:Signature_data.equality_signatures
+
+    let zero () =
+      Alcotest.(check' string)
+        ~msg:"zeros are equal" ~expected:Tezos_data.zero
+        ~actual:Signature_data.zero
   end
 end

deku-p/src/core/crypto/tests/test_ed25519.ml

@@ -108,5 +108,6 @@ let run () =
             Test_signature_data.verified_after_conversion;
           test_case "compare" `Quick Test_signature_data.compare;
           test_case "equality" `Quick Test_signature_data.equality;
+          test_case "zero" `Quick Test_signature_data.zero;
         ] );
     ]