raftengine: add missing tests, document Close order, and deduplicate remaining engine wrappers

Address @claude review feedback:
- Add durationToTicks unit tests (zero tick, exact, remainder, below min)
- Add dest_already_exists validation test for MigrateFSMStore
- Document Engine.Close must be called before FactoryResult.Close
- Deduplicate remaining 8 instances of hashicorpraftengine.New() in tests

Author: bootjp

internal/raftengine/factory.go

@@ -18,7 +18,8 @@ type FactoryResult struct {
 	RegisterTransport func(grpc.ServiceRegistrar)
 	// Close releases engine-specific resources that are not owned by
 	// Engine.Close (e.g. raft log stores, transport managers). Callers
-	// must still call Engine.Close separately.
+	// must call Engine.Close first to ensure the raft instance is fully
+	// shut down before the underlying stores and transports are released.
 	Close func() error
 }
 

internal/raftengine/hashicorp/migrate_test.go

@@ -63,6 +63,14 @@ func TestMigrateFSMStoreValidation(t *testing.T) {
 		require.Error(t, err)
 		require.Contains(t, err.Error(), "at least one peer is required")
 	})
+
+	t.Run("dest_already_exists", func(t *testing.T) {
+		dest := t.TempDir() // already exists
+		peers := []hashicorpraftengine.MigrationPeer{{ID: "n1", Address: "127.0.0.1:7001"}}
+		_, err := hashicorpraftengine.MigrateFSMStore("/some/path", dest, peers)
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "already exists")
+	})
 }
 
 func TestMigrateFSMStoreSeedsHashicorpDataDir(t *testing.T) {

kv/lock_resolver_test.go

@@ -209,8 +209,9 @@ func TestLockResolver_LeaderOnlyExecution(t *testing.T) {
 	r, stop := newSingleRaft(t, "lr-leader", NewKvFSM(st))
 	defer stop()
 
+	e := hashicorpraftengine.New(r)
 	groups := map[uint64]*ShardGroup{
-		1: {Engine: hashicorpraftengine.New(r), Store: st, Txn: NewLeaderProxyWithEngine(hashicorpraftengine.New(r))},
+		1: {Engine: e, Store: st, Txn: NewLeaderProxyWithEngine(e)},
 	}
 	ss := NewShardStore(engine, groups)
 	lr := NewLockResolver(ss, groups, nil)
@@ -239,8 +240,9 @@ func TestLockResolver_CloseStopsBackground(t *testing.T) {
 	r, stop := newSingleRaft(t, "lr-close", NewKvFSM(st))
 	defer stop()
 
+	e := hashicorpraftengine.New(r)
 	groups := map[uint64]*ShardGroup{
-		1: {Engine: hashicorpraftengine.New(r), Store: st, Txn: NewLeaderProxyWithEngine(hashicorpraftengine.New(r))},
+		1: {Engine: e, Store: st, Txn: NewLeaderProxyWithEngine(e)},
 	}
 	ss := NewShardStore(engine, groups)
 	lr := NewLockResolver(ss, groups, nil)

kv/shard_store_txn_lock_test.go

@@ -97,8 +97,9 @@ func TestShardStoreGetAt_ReturnsTxnLockedForPendingLock(t *testing.T) {
 	r1, stop1 := newSingleRaft(t, "g1", NewKvFSM(st1))
 	defer stop1()
 
+	e1 := hashicorpraftengine.New(r1)
 	groups := map[uint64]*ShardGroup{
-		1: {Engine: hashicorpraftengine.New(r1), Store: st1, Txn: NewLeaderProxyWithEngine(hashicorpraftengine.New(r1))},
+		1: {Engine: e1, Store: st1, Txn: NewLeaderProxyWithEngine(e1)},
 	}
 	shardStore := NewShardStore(engine, groups)
 
@@ -233,8 +234,9 @@ func TestShardStoreScanAt_ReturnsTxnLockedForPendingLock(t *testing.T) {
 	r1, stop1 := newSingleRaft(t, "g1", NewKvFSM(st1))
 	defer stop1()
 
+	e1 := hashicorpraftengine.New(r1)
 	groups := map[uint64]*ShardGroup{
-		1: {Engine: hashicorpraftengine.New(r1), Store: st1, Txn: NewLeaderProxyWithEngine(hashicorpraftengine.New(r1))},
+		1: {Engine: e1, Store: st1, Txn: NewLeaderProxyWithEngine(e1)},
 	}
 	shardStore := NewShardStore(engine, groups)
 
@@ -262,8 +264,9 @@ func TestShardStoreScanAt_ReturnsTxnLockedForPendingLockWithoutCommittedValue(t
 	r1, stop1 := newSingleRaft(t, "g1", NewKvFSM(st1))
 	defer stop1()
 
+	e1 := hashicorpraftengine.New(r1)
 	groups := map[uint64]*ShardGroup{
-		1: {Engine: hashicorpraftengine.New(r1), Store: st1, Txn: NewLeaderProxyWithEngine(hashicorpraftengine.New(r1))},
+		1: {Engine: e1, Store: st1, Txn: NewLeaderProxyWithEngine(e1)},
 	}
 	shardStore := NewShardStore(engine, groups)
 
@@ -291,8 +294,9 @@ func TestShardStoreScanAt_ReturnsTxnLockedWhenPendingLockExceedsUserLimit(t *tes
 	r1, stop1 := newSingleRaft(t, "g1", NewKvFSM(st1))
 	defer stop1()
 
+	e1 := hashicorpraftengine.New(r1)
 	groups := map[uint64]*ShardGroup{
-		1: {Engine: hashicorpraftengine.New(r1), Store: st1, Txn: NewLeaderProxyWithEngine(hashicorpraftengine.New(r1))},
+		1: {Engine: e1, Store: st1, Txn: NewLeaderProxyWithEngine(e1)},
 	}
 	shardStore := NewShardStore(engine, groups)
 

kv/sharded_coordinator_abort_test.go

@@ -48,8 +48,9 @@ func TestShardedAbortRollback_PrepareFailOnShard2_CleansShard1Locks(t *testing.T
 	s2 := store.NewMVCCStore()
 	failTxn := &failingTransactional{err: errors.New("simulated shard2 prepare failure")}
 
+	e1 := hashicorpraftengine.New(r1)
 	groups := map[uint64]*ShardGroup{
-		1: {Engine: hashicorpraftengine.New(r1), Store: s1, Txn: NewLeaderProxyWithEngine(hashicorpraftengine.New(r1))},
+		1: {Engine: e1, Store: s1, Txn: NewLeaderProxyWithEngine(e1)},
 		2: {Store: s2, Txn: failTxn},
 	}
 

kv/sharded_coordinator_del_prefix_test.go

@@ -341,8 +341,9 @@ func TestShardedCoordinator_DelPrefixPreservesTxnKeys(t *testing.T) {
 	r1, stop1 := newSingleRaft(t, "dp-txn-g1", NewKvFSM(s1))
 	t.Cleanup(stop1)
 
+	e1 := hashicorpraftengine.New(r1)
 	groups := map[uint64]*ShardGroup{
-		1: {Engine: hashicorpraftengine.New(r1), Store: s1, Txn: NewLeaderProxyWithEngine(hashicorpraftengine.New(r1))},
+		1: {Engine: e1, Store: s1, Txn: NewLeaderProxyWithEngine(e1)},
 	}
 	shardStore := NewShardStore(engine, groups)
 	coord := NewShardedCoordinator(engine, groups, 1, NewHLC(), shardStore)

main_bootstrap_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"testing"
+	"time"
 
 	"github.com/hashicorp/raft"
 	"github.com/stretchr/testify/require"
@@ -67,3 +68,23 @@ func TestResolveBootstrapServers(t *testing.T) {
 		require.ErrorIs(t, err, ErrNoBootstrapMembersConfigured)
 	})
 }
+
+func TestDurationToTicks(t *testing.T) {
+	t.Parallel()
+
+	t.Run("zero tick returns min", func(t *testing.T) {
+		require.Equal(t, 5, durationToTicks(200*time.Millisecond, 0, 5))
+	})
+
+	t.Run("exact division", func(t *testing.T) {
+		require.Equal(t, 20, durationToTicks(200*time.Millisecond, 10*time.Millisecond, 1))
+	})
+
+	t.Run("remainder rounds up", func(t *testing.T) {
+		require.Equal(t, 21, durationToTicks(205*time.Millisecond, 10*time.Millisecond, 1))
+	})
+
+	t.Run("below min returns min", func(t *testing.T) {
+		require.Equal(t, 10, durationToTicks(50*time.Millisecond, 10*time.Millisecond, 10))
+	})
+}