diff --git a/internal/pkg/core/olt_state_transitions_test.go b/internal/pkg/core/olt_state_transitions_test.go
new file mode 100644
index 0000000..9c2be8d
--- /dev/null
+++ b/internal/pkg/core/olt_state_transitions_test.go
@@ -0,0 +1,189 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package core
+
+import (
+	"context"
+	"github.com/opencord/voltha-openolt-adapter/internal/pkg/olterrors"
+	"reflect"
+	"testing"
+	"time"
+)
+
+/**
+Get's the transition Map with current state of the device.
+*/
+func getTranisitions() map[Trigger]Transition {
+	transitions := make(map[Trigger]Transition)
+	transition := Transition{
+		previousState: []DeviceState{deviceStateConnected},
+		currentState:  deviceStateConnected,
+	}
+	transitions[DeviceInit] = transition
+	return transitions
+}
+
+/**
+Get's the transition Map with after Transition func added.
+*/
+func getTranisitionsAfter() map[Trigger]Transition {
+	transitions := make(map[Trigger]Transition)
+	transition := Transition{
+		previousState: []DeviceState{deviceStateConnected},
+		currentState:  deviceStateConnected,
+		after: []TransitionHandler{func(ctx context.Context) error {
+			return nil
+		}, func(ctx context.Context) error {
+			return olterrors.ErrStateTransition
+		}},
+	}
+	transitions[GrpcConnected] = transition
+	return transitions
+}
+
+/**
+Get's the transition Map with before Transition func added.
+*/
+func getTranisitionsBefore() map[Trigger]Transition {
+	transitions := make(map[Trigger]Transition)
+	transition := Transition{
+		previousState: []DeviceState{deviceStateConnected},
+		currentState:  deviceStateConnected,
+		before: []TransitionHandler{func(ctx context.Context) error {
+			return nil
+		}, func(ctx context.Context) error {
+			return olterrors.ErrStateTransition
+		}},
+	}
+	transitions[GrpcConnected] = transition
+	return transitions
+}
+
+/**
+Check's Creation of transition Map, return's NewTransitionMap.
+*/
+func TestNewTransitionMap(t *testing.T) {
+	type args struct {
+		dh *DeviceHandler
+	}
+	tests := []struct {
+		name string
+		args args
+		want *TransitionMap
+	}{
+		{"NewTransitionMap-1", args{newMockDeviceHandler()}, &TransitionMap{}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := NewTransitionMap(tt.args.dh); reflect.TypeOf(got) != reflect.TypeOf(tt.want) {
+				t.Errorf("NewTransitionMap() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+/**
+Checks the different transition of the device handled properly.
+*/
+func TestTransitionMap_Handle(t *testing.T) {
+	type fields struct {
+		transitions        map[Trigger]Transition
+		currentDeviceState DeviceState
+	}
+	type args struct {
+		trigger Trigger
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+	}{
+		{"Handle-1", fields{getTranisitions(), deviceStateDown}, args{GrpcConnected}},
+		{"Handle-2", fields{getTranisitions(), deviceStateConnected}, args{GrpcConnected}},
+		{"Handle-3", fields{getTranisitionsBefore(), deviceStateConnected}, args{GrpcConnected}},
+		{"Handle-4", fields{getTranisitionsAfter(), deviceStateConnected}, args{GrpcConnected}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tMap := &TransitionMap{
+				transitions:        tt.fields.transitions,
+				currentDeviceState: tt.fields.currentDeviceState,
+			}
+			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+			defer cancel()
+			tMap.Handle(ctx, tt.args.trigger)
+		})
+	}
+}
+
+/**
+Check's if the transition is valid or not.
+*/
+func TestTransitionMap_isValidTransition(t *testing.T) {
+	type fields struct {
+		transitions        map[Trigger]Transition
+		currentDeviceState DeviceState
+	}
+	type args struct {
+		trigger Trigger
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   bool
+	}{
+		{"isValidTransition-1", fields{getTranisitions(), deviceStateConnected}, args{DeviceInit},
+			true},
+		{"isValidTransition-2", fields{getTranisitions(), deviceStateDown}, args{GrpcConnected},
+			false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tMap := &TransitionMap{
+				transitions:        tt.fields.transitions,
+				currentDeviceState: tt.fields.currentDeviceState,
+			}
+			if got := tMap.isValidTransition(tt.args.trigger); reflect.TypeOf(got) != reflect.TypeOf(tt.want) {
+				t.Errorf("isValidTransition() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+/**
+Get's the After/Before transition method's function name.
+*/
+func Test_funcName(t *testing.T) {
+	type args struct {
+		f interface{}
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{"FuncName-1", args{newMockDeviceHandler()}, ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := funcName(tt.args.f); got != tt.want {
+				t.Errorf("funcName() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}