asset: add GroupKeyRevealV1 encoding/decoding unit test

Unit test also validates spend script control block.

Author: ffranr

asset/group_key_reveal_test.go

@@ -0,0 +1,144 @@
+package asset
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcd/txscript"
+	"github.com/lightninglabs/taproot-assets/fn"
+	"github.com/lightninglabs/taproot-assets/internal/test"
+	"github.com/stretchr/testify/require"
+)
+
+type testCaseGkrEncodeDecode struct {
+	testName string
+
+	internalKey       btcec.PublicKey
+	genesisAssetID    ID
+	customSubtreeRoot fn.Option[chainhash.Hash]
+}
+
+// GroupKeyReveal generates a GroupKeyReveal instance from the test case.
+func (tc testCaseGkrEncodeDecode) GroupKeyReveal() (GroupKeyReveal, error) {
+	gkr, err := NewGroupKeyRevealV1(
+		tc.internalKey, tc.genesisAssetID, tc.customSubtreeRoot,
+	).Unpack()
+
+	return &gkr, err
+}
+
+func TestGroupKeyTapscriptEncodeDecode(t *testing.T) {
+	t.Parallel()
+
+	// Create a random internal public key.
+	internalKey := *(test.RandPubKey(t))
+
+	// Create a random genesis asset ID.
+	randomAssetIdBytes := test.RandBytes(32)
+	genesisAssetID := ID(randomAssetIdBytes)
+
+	// Construct a custom user script leaf. This is used to validate any
+	// control block.
+	customScriptLeaf := txscript.NewBaseTapLeaf(
+		[]byte("I'm a custom user script"),
+	)
+	customSubtreeRoot := fn.Some(customScriptLeaf.TapHash())
+
+	testCases := []testCaseGkrEncodeDecode{
+		{
+			testName: "no custom root",
+
+			internalKey:       internalKey,
+			genesisAssetID:    genesisAssetID,
+			customSubtreeRoot: fn.None[chainhash.Hash](),
+		},
+		{
+			testName: "with custom root",
+
+			internalKey:       internalKey,
+			genesisAssetID:    genesisAssetID,
+			customSubtreeRoot: customSubtreeRoot,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.testName, func(tt *testing.T) {
+			gkr, err := tc.GroupKeyReveal()
+			require.NoError(tt, err)
+
+			groupPubKey, err := gkr.GroupPubKey(tc.genesisAssetID)
+			require.NoError(tt, err)
+
+			// Encode the GroupKeyReveal into buffer.
+			var buffer bytes.Buffer
+			var scratchBuffEncode [8]byte
+			err = GroupKeyRevealEncoder(
+				&buffer, &gkr, &scratchBuffEncode,
+			)
+			require.NoError(tt, err)
+
+			// Decode the GroupKeyReveal from buffer.
+			var gkrDecoded GroupKeyReveal
+			var scratchBuffDecode [8]byte
+			err = GroupKeyRevealDecoder(
+				&buffer, &gkrDecoded, &scratchBuffDecode,
+				uint64(buffer.Len()),
+			)
+			require.NoError(tt, err)
+
+			// Prepare the original GroupKeyReveal for comparison.
+			// Remove fields which are not included in
+			// encoding/decoding.
+			gkrV1, ok := gkr.(*GroupKeyRevealV1)
+			require.True(tt, ok)
+			gkrV1.tapscript.customSubtreeInclusionProof = nil
+
+			// Compare decoded group key reveal with the original.
+			require.Equal(tt, gkrV1, gkrDecoded)
+
+			// Ensure the decoded group public key matches the
+			// original.
+			groupPubKeyDecoded, err := gkrDecoded.GroupPubKey(
+				tc.genesisAssetID,
+			)
+			require.NoError(tt, err)
+
+			require.Equal(
+				tt, groupPubKey, groupPubKeyDecoded,
+				"decoded GroupKeyReveal group pub key does "+
+					"not match original",
+			)
+
+			// If a custom subtree root is set, ensure the control
+			// block is correct.
+			if tc.customSubtreeRoot.IsSome() {
+				gkrDecodedV1, ok :=
+					gkrDecoded.(*GroupKeyRevealV1)
+				require.True(tt, ok)
+
+				ctrlBlock, err :=
+					gkrDecodedV1.ScriptSpendControlBlock(
+						tc.genesisAssetID,
+					).Unpack()
+				require.NoError(tt, err)
+
+				// Use the control block and the custom spend
+				// script to compute the root hash.
+				computedRoot := chainhash.Hash(
+					ctrlBlock.RootHash(
+						customScriptLeaf.Script,
+					),
+				)
+
+				// Ensure the computed root matches the custom
+				// subtree root.
+				require.Equal(
+					tt, gkrDecodedV1.tapscript.root,
+					computedRoot,
+				)
+			}
+		})
+	}
+}