diff --git a/internal/internal_event_handlers.go b/internal/internal_event_handlers.go
index e009e7ca0..b419d6931 100644
--- a/internal/internal_event_handlers.go
+++ b/internal/internal_event_handlers.go
@@ -463,12 +463,6 @@ func (wc *workflowEnvironmentImpl) GenerateSequence() int32 {
 	return result
 }
 
-func (wc *workflowEnvironmentImpl) CreateNewDecision(decisionType m.DecisionType) *m.Decision {
-	return &m.Decision{
-		DecisionType: common.DecisionTypePtr(decisionType),
-	}
-}
-
 func (wc *workflowEnvironmentImpl) ExecuteActivity(parameters executeActivityParams, callback resultHandler) *activityInfo {
 	scheduleTaskAttr := &m.ScheduleActivityTaskDecisionAttributes{}
 	if parameters.ActivityID == nil || *parameters.ActivityID == "" {
diff --git a/internal/internal_event_handlers_test.go b/internal/internal_event_handlers_test.go
index 5176b2ac5..4ba96b2a2 100644
--- a/internal/internal_event_handlers_test.go
+++ b/internal/internal_event_handlers_test.go
@@ -23,6 +23,7 @@ package internal
 import (
 	"encoding/json"
 	"testing"
+	"time"
 
 	"go.uber.org/cadence/internal/common/testlogger"
 
@@ -68,6 +69,13 @@ func TestReplayAwareLogger(t *testing.T) {
 	assert.NotContains(t, messages, "replay info")
 	assert.Contains(t, messages, "normal2 info")
 	assert.Contains(t, messages, "replay2 info")
+
+	isReplay = true
+	enableLoggingInReplay = true
+	parentCore := wrapLogger(&isReplay, &enableLoggingInReplay)
+	wrappedCore := parentCore(core).With([]zapcore.Field{zap.String("key", "value")}).(*replayAwareZapCore)
+	assert.Equal(t, wrappedCore.isReplay, &isReplay)
+	assert.Equal(t, wrappedCore.enableLoggingInReplay, &enableLoggingInReplay)
 }
 
 func testDecodeValueHelper(t *testing.T, env *workflowEnvironmentImpl) {
@@ -929,6 +937,50 @@ func TestEventHandler_handleMarkerRecorded_failures(t *testing.T) {
 	}
 }
 
+func TestWorkflowEnvironment_sessions(t *testing.T) {
+	handler := testWorkflowExecutionEventHandler(t, newRegistry())
+	testSession := &SessionInfo{
+		SessionID: "test-session",
+		HostName:  "test-host",
+	}
+	handler.AddSession(testSession)
+	list := handler.getOpenSessions()
+	assert.Contains(t, list, testSession)
+	handler.RemoveSession(testSession.SessionID)
+	list = handler.getOpenSessions()
+	assert.Empty(t, list)
+}
+
+func TestWorkflowExecutionEnvironment_NewTimer_immediate_calls(t *testing.T) {
+	t.Run("immediate call", func(t *testing.T) {
+		handler := testWorkflowExecutionEventHandler(t, newRegistry())
+		handlerCalled := false
+		res := handler.NewTimer(0, func(result []byte, err error) {
+			assert.NoError(t, err)
+			handlerCalled = true
+		})
+		assert.True(t, handlerCalled, "handler must be called immediately")
+		assert.Nil(t, res)
+	})
+	t.Run("negative duration", func(t *testing.T) {
+		handler := testWorkflowExecutionEventHandler(t, newRegistry())
+		handlerCalled := false
+		res := handler.NewTimer(-2*time.Second, func(result []byte, err error) {
+			handlerCalled = true
+			assert.ErrorContains(t, err, "negative duration provided")
+		})
+		assert.Nil(t, res)
+		assert.True(t, handlerCalled, "handler must be called immediately")
+	})
+	t.Run("timer cancellation", func(t *testing.T) {
+		handler := testWorkflowExecutionEventHandler(t, newRegistry())
+		timer := handler.NewTimer(time.Second, func(result []byte, err error) {
+			assert.ErrorIs(t, err, ErrCanceled)
+		})
+		handler.RequestCancelTimer(timer.timerID)
+	})
+}
+
 func testWorkflowExecutionEventHandler(t *testing.T, registry *registry) *workflowExecutionEventHandlerImpl {
 	return newWorkflowExecutionEventHandler(
 		testWorkflowInfo,