chain/test: Add ABCI begin block rolling seed test

CHANGELOG_UNRELEASED.md

@@ -10,6 +10,7 @@
 
 ### Chain
 
+- (chore) [\#2130](https://github.com/bandprotocol/bandchain/pull/2130) Add ABCI begin block rolling seed test.
 - (bug) [\#2075](https://github.com/bandprotocol/bandchain/pull/2075) Add height check when sync on db and fix external id can be zero.
 - (bug) [\#2125](https://github.com/bandprotocol/bandchain/pull/2125) Fix request with duplicate external id and empty raw request bug.
 - (chore) [\#2126](https://github.com/bandprotocol/bandchain/pull/2126) More test cleanups in request and result keepers.

chain/x/oracle/abci_test.go

@@ -0,0 +1,38 @@
+package oracle_test
+
+import (
+	"encoding/hex"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	abci "github.com/tendermint/tendermint/abci/types"
+
+	"github.com/bandprotocol/bandchain/chain/x/oracle/testapp"
+)
+
+func fromHex(hexStr string) []byte {
+	res, err := hex.DecodeString(hexStr)
+	if err != nil {
+		panic(err)
+	}
+	return res
+}
+
+func TestRollingSeedCorrect(t *testing.T) {
+	app, ctx, k := testapp.CreateTestInput()
+	// Initially rolling seed should be all zeros.
+	require.Equal(t, fromHex("0000000000000000000000000000000000000000000000000000000000000000"), k.GetRollingSeed(ctx))
+	// Every begin block, the rolling seed should get updated.
+	app.BeginBlocker(ctx, abci.RequestBeginBlock{
+		Hash: fromHex("0100000000000000000000000000000000000000000000000000000000000000"),
+	})
+	require.Equal(t, fromHex("0000000000000000000000000000000000000000000000000000000000000001"), k.GetRollingSeed(ctx))
+	app.BeginBlocker(ctx, abci.RequestBeginBlock{
+		Hash: fromHex("0200000000000000000000000000000000000000000000000000000000000000"),
+	})
+	require.Equal(t, fromHex("0000000000000000000000000000000000000000000000000000000000000102"), k.GetRollingSeed(ctx))
+	app.BeginBlocker(ctx, abci.RequestBeginBlock{
+		Hash: fromHex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"),
+	})
+	require.Equal(t, fromHex("00000000000000000000000000000000000000000000000000000000000102ff"), k.GetRollingSeed(ctx))
+}