diff --git a/state/stage_test.go b/state/stage_test.go
index 3aa242950..f747574eb 100644
--- a/state/stage_test.go
+++ b/state/stage_test.go
@@ -6,6 +6,7 @@
 package state
 
 import (
+	"errors"
 	"math/big"
 	"testing"
 
@@ -17,9 +18,7 @@ import (
 
 func TestStage(t *testing.T) {
 	db := muxdb.NewMem()
-
 	state := New(db, thor.Bytes32{}, 0, 0, 0)
-
 	addr := thor.BytesToAddress([]byte("acc1"))
 
 	balance := big.NewInt(10)
@@ -56,3 +55,43 @@ func TestStage(t *testing.T) {
 		assert.Equal(t, M(v, nil), M(state.GetStorage(addr, k)))
 	}
 }
+
+func TestStageCommitError(t *testing.T) {
+	db := muxdb.NewMem()
+	state := New(db, thor.Bytes32{}, 0, 0, 0)
+
+	// Set up the state with an account, balance, code, and storage.
+	addr := thor.BytesToAddress([]byte("acc1"))
+	balance := big.NewInt(10)
+	code := []byte{1, 2, 3}
+	storage := map[thor.Bytes32]thor.Bytes32{
+		thor.BytesToBytes32([]byte("s1")): thor.BytesToBytes32([]byte("v1")),
+		thor.BytesToBytes32([]byte("s2")): thor.BytesToBytes32([]byte("v2")),
+		thor.BytesToBytes32([]byte("s3")): thor.BytesToBytes32([]byte("v3")),
+	}
+
+	state.SetBalance(addr, balance)
+	state.SetCode(addr, code)
+	for k, v := range storage {
+		state.SetStorage(addr, k, v)
+	}
+
+	// Prepare the stage with the current state.
+	stage, err := state.Stage(1, 0)
+	assert.Nil(t, err, "Stage should not return an error")
+
+	// Mock a commit function to simulate an error.
+	commitFuncWithError := func() error {
+		return errors.New("commit error")
+	}
+
+	// Include the error-producing commit function in the stage's commits.
+	stage.commits = append(stage.commits, commitFuncWithError)
+
+	// Attempt to commit changes.
+	_, err = stage.Commit()
+
+	// Assert that an error is returned.
+	assert.NotNil(t, err, "Commit should return an error")
+	assert.EqualError(t, err, "state: commit error", "The error message should match the mock error")
+}
diff --git a/state/state_test.go b/state/state_test.go
index 87ea73841..daa5007d7 100644
--- a/state/state_test.go
+++ b/state/state_test.go
@@ -120,6 +120,63 @@ func TestEnergy(t *testing.T) {
 	assert.Equal(t, x, bal1)
 }
 
+func TestEncodeDecodeStorage(t *testing.T) {
+	db := muxdb.NewMem()
+	state := New(db, thor.Bytes32{}, 0, 0, 0)
+
+	// Create an account and key
+	addr := thor.BytesToAddress([]byte("account1"))
+	key := thor.BytesToBytes32([]byte("key"))
+
+	// Original value to be encoded and then decoded
+	originalValue := []byte("value")
+
+	// Encoding function
+	encodingFunc := func() ([]byte, error) {
+		return rlp.EncodeToBytes(originalValue)
+	}
+
+	// Encode and store the value
+	err := state.EncodeStorage(addr, key, encodingFunc)
+	assert.Nil(t, err, "EncodeStorage should not return an error")
+
+	// Function to decode the storage value
+	var decodedValue []byte
+	decodeFunc := func(b []byte) error {
+		var err error
+		err = rlp.DecodeBytes(b, &decodedValue)
+		return err
+	}
+
+	// Decode the stored value
+	err = state.DecodeStorage(addr, key, decodeFunc)
+	assert.Nil(t, err, "DecodeStorage should not return an error")
+
+	// Verify that the decoded value matches the original value
+	assert.Equal(t, originalValue, decodedValue, "decoded value should match the original value")
+}
+
+func TestBuildStorageTrie(t *testing.T) {
+	db := muxdb.NewMem()
+	state := New(db, thor.Bytes32{}, 0, 0, 0)
+
+	// Create an account and set storage values
+	addr := thor.BytesToAddress([]byte("account1"))
+	key1 := thor.BytesToBytes32([]byte("key1"))
+	value1 := thor.BytesToBytes32([]byte("value1"))
+	key2 := thor.BytesToBytes32([]byte("key2"))
+	value2 := thor.BytesToBytes32([]byte("value2"))
+
+	state.SetRawStorage(addr, key1, value1[:])
+	state.SetRawStorage(addr, key2, value2[:])
+
+	assert.Equal(t, M(rlp.RawValue(value1[:]), nil), M(state.GetRawStorage(addr, key1)))
+
+	// Build the storage trie
+	_, err := state.BuildStorageTrie(addr)
+	assert.Nil(t, err, "error should be nil")
+}
+
 func TestStorage(t *testing.T) {
 	db := muxdb.NewMem()
 	st := New(db, thor.Bytes32{}, 0, 0, 0)
diff --git a/state/stater_test.go b/state/stater_test.go
new file mode 100644
index 000000000..ebe40ae2d
--- /dev/null
+++ b/state/stater_test.go
@@ -0,0 +1,25 @@
+package state
+
+import (
+	"testing"
+
+	"github.com/vechain/thor/muxdb"
+	"github.com/vechain/thor/thor"
+)
+
+func TestStater(t *testing.T) {
+	db := muxdb.NewMem()
+	stater := NewStater(db)
+
+	// Example State
+	root := thor.Bytes32{}
+	blockNum := uint32(1)
+	blockConflicts := uint32(0)
+	steadyBlockNum := uint32(1)
+
+	state := stater.NewState(root, blockNum, blockConflicts, steadyBlockNum)
+
+	if state == nil {
+		t.Errorf("NewState returned nil")
+	}
+}