Cardano blueprint localstate query tests

[ch1bo]

Explores how we could test the LocalStatQuery API that is being created in course of the blueprint initiative.

• This is adding a cardano-blueprint submodule from which local state query and result cbor examples are taken to test serialization roundtrips.

• Changes SystemStartResult to hold big.Int for Year and Picoseconds as the CDDL (and at least the Haskell server) are using unbounded integers

  type SystemStartResult struct {
      // Tells the CBOR decoder to convert to/from a struct and a CBOR array
      _           struct{} `cbor:",toarray"`
      Year        big.Int
      Day         int
      Picoseconds big.Int
  }

  • This required a few additional custom methods on SystemStartResult to make roundtrips work. Happy for some feedback in how to improve / avoid those changes.

TODO

Extended TestDecode in the localstatequery/messages_test.go to also assert the decoded Result being equal. This is failing right now though and I'm not sure why in:

gouroboros/protocol/localstatequery/messages_test.go

Lines 131 to 145 in e36727b

	// cast msg to MsgResult and further try to decode cbor
	if m, ok := msg.(*MsgResult); ok && test.Result != nil {
	var decoded = reflect.New(reflect.TypeOf(test.Result))
	_, err := cbor.Decode(m.Result, decoded.Interface())
	if err != nil {
	t.Fatalf("failed to decode result: %s", err)
	}
	if !reflect.DeepEqual(decoded.Interface(), test.Result) {
	t.Fatalf(
	"MsgResult content did not decode to expected Result object\n got: %#v\n wanted: %#v",
	decoded.Interface(),
	test.Result,
	)
	}
	}

--- FAIL: TestDecode (0.00s)
    messages_test.go:139: MsgResult content did not decode to expected Result object
          got:    &localstatequery.SystemStartResult{_:struct {}{}, Year:big.Int{neg:false, abs:big.nat{0x7264a1f8c5026abc, 0x7f99e05018460693, 0xc59141d0ba6cc89, 0x65fea6236047}}, Day:-4205646576720553090, Picoseconds:big.Int{neg:true, abs:big.nat{0x8ba3b6818e7c258b, 0x91db8b1c2237dd91, 0x5e3cc5aadf6619e7, 0x50670ee65e80}}}
          wanted: localstatequery.SystemStartResult{_:struct {}{}, Year:big.Int{neg:false, abs:big.nat{0x7264a1f8c5026abc, 0x7f99e05018460693, 0xc59141d0ba6cc89, 0x65fea6236047}}, Day:-4205646576720553090, Picoseconds:big.Int{neg:true, abs:big.nat{0x8ba3b6818e7c258b, 0x91db8b1c2237dd91, 0x5e3cc5aadf6619e7, 0x50670ee65e80}}}

[agaffney]

That failing test you noted is due to pointer vs. non-pointer in the DeepEqual() comparison

[agaffney]

@ch1bo it took a bit of playing around, but I figured out how to fix the test failure. Reflection is fun!

diff --git a/protocol/localstatequery/messages_test.go b/protocol/localstatequery/messages_test.go
index 4156f5f..cbe1fba 100644
--- a/protocol/localstatequery/messages_test.go
+++ b/protocol/localstatequery/messages_test.go
@@ -135,10 +135,10 @@ func TestDecode(t *testing.T) {
                        if err != nil {
                                t.Fatalf("failed to decode result: %s", err)
                        }
-                       if !reflect.DeepEqual(decoded.Interface(), test.Result) {
+                       if !reflect.DeepEqual(reflect.Indirect(decoded).Interface(), test.Result) {
                                t.Fatalf(
                                        "MsgResult content did not decode to expected Result object\n  got:    %#v\n  wanted: %#v",
-                                       decoded.Interface(),
+                                       reflect.Indirect(decoded).Interface(),
                                        test.Result,
                                )
                        }