fix: DiffCollectionsMigration hash function not used correctly (#17143)

testutil/collections.go

@@ -66,9 +66,9 @@ func DiffCollectionsMigration(
 		h.Write(it.Value())
 	}
 
-	hash := sha256.Sum256(nil)
-	if hex.EncodeToString(hash[:]) != targetHash {
-		return fmt.Errorf("hashes don't match: %s != %s", hex.EncodeToString(hash[:]), targetHash)
+	hash := h.Sum(nil)
+	if hex.EncodeToString(hash) != targetHash {
+		return fmt.Errorf("hashes don't match: %s != %s", hex.EncodeToString(hash), targetHash)
 	}
 
 	return nil

testutil/collections_test.go

@@ -0,0 +1,54 @@
+package testutil_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	storetypes "cosmossdk.io/store/types"
+
+	"github.com/cosmos/cosmos-sdk/testutil"
+)
+
+func TestDiffCollectionsMigration(t *testing.T) {
+	key := storetypes.NewKVStoreKey("test")
+	ctx := testutil.DefaultContext(key, storetypes.NewTransientStoreKey("transient"))
+
+	// First try with some invalid hash
+	err := testutil.DiffCollectionsMigration(
+		ctx,
+		key,
+		5,
+		func(i int64) {
+			ctx.KVStore(key).Set([]byte{byte(i)}, []byte{byte(i)})
+		},
+		"abcdef0123456789",
+	)
+	require.Error(t, err)
+
+	// Now reset and try with the correct hash
+	ctx = testutil.DefaultContext(key, storetypes.NewTransientStoreKey("transient"))
+	err = testutil.DiffCollectionsMigration(
+		ctx,
+		key,
+		5,
+		func(i int64) {
+			ctx.KVStore(key).Set([]byte{byte(i)}, []byte{byte(i)})
+		},
+		"79541ed9da9c16cb7a1d43d5a3d5f6ee31a873c85a6cb4334fb99e021ee0e556",
+	)
+	require.NoError(t, err)
+
+	// Change the data a little and it will result in an error
+	ctx = testutil.DefaultContext(key, storetypes.NewTransientStoreKey("transient"))
+	err = testutil.DiffCollectionsMigration(
+		ctx,
+		key,
+		5,
+		func(i int64) {
+			ctx.KVStore(key).Set([]byte{byte(i)}, []byte{byte(i + 1)})
+		},
+		"79541ed9da9c16cb7a1d43d5a3d5f6ee31a873c85a6cb4334fb99e021ee0e556",
+	)
+	require.Error(t, err)
+}