diff --git a/.travis.yml b/.travis.yml
index e818916f..9558bb43 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,10 +1,10 @@
 language: go
 
 go:
-  - 1.8
   - 1.9
   - 1.10.x
   - 1.11.x
+  - 1.12.x
   - master
 
 before_install:
@@ -16,7 +16,7 @@ install:
 
 script:
   - go test -v ./...
-  - goveralls -service=travis-ci
+  - goveralls -service=travis-ci -ignore=zendesk/mock/client.go
 
 notifications:
   email: false
diff --git a/Gopkg.lock b/Gopkg.lock
index 10ef8111..47f62d72 100644
--- a/Gopkg.lock
+++ b/Gopkg.lock
@@ -1,9 +1,15 @@
 # This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
 
 
+[[projects]]
+  name = "github.com/golang/mock"
+  packages = ["gomock"]
+  revision = "51421b967af1f557f93a59e0057aaf15ca02e29c"
+  version = "v1.2.0"
+
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
-  input-imports = []
+  inputs-digest = "926eb2ebfa68b0b0c883ec5a7f201ddd3c013e7e16ba99fc3710d9ed1a57e1b3"
   solver-name = "gps-cdcl"
   solver-version = 1
diff --git a/zendesk/api.go b/zendesk/api.go
new file mode 100644
index 00000000..afd56976
--- /dev/null
+++ b/zendesk/api.go
@@ -0,0 +1,13 @@
+package zendesk
+
+//go:generate  mockgen -destination=mock/client.go -package=mock -mock_names=API=Client github.com/nukosuke/go-zendesk/zendesk API
+
+// API an interface containing all of the zendesk client methods
+type API interface {
+	GroupAPI
+	LocaleAPI
+	TicketFieldAPI
+	TicketFormAPI
+	TriggerAPI
+	UserAPI
+}
diff --git a/zendesk/group.go b/zendesk/group.go
index 9a8c0424..596f080d 100644
--- a/zendesk/group.go
+++ b/zendesk/group.go
@@ -16,6 +16,12 @@ type Group struct {
 	UpdatedAt time.Time `json:"updated_at,omitempty"`
 }
 
+// GroupAPI an interface containing all methods associated with zendesk groups
+type GroupAPI interface {
+	GetGroups() ([]Group, Page, error)
+	CreateGroup(group Group) (Group, error)
+}
+
 // GetGroups fetches group list
 // https://developer.zendesk.com/rest_api/docs/support/groups#list-groups
 func (z *Client) GetGroups() ([]Group, Page, error) {
diff --git a/zendesk/locale.go b/zendesk/locale.go
index fd09b061..b0343dec 100644
--- a/zendesk/locale.go
+++ b/zendesk/locale.go
@@ -16,6 +16,11 @@ type Locale struct {
 	UpdatedAt time.Time `json:"updated_at"`
 }
 
+// LocaleAPI an interface containing all of the local related zendesk methods
+type LocaleAPI interface {
+	GetLocales() ([]Locale, error)
+}
+
 // GetLocales lists the translation locales available for the account.
 // https://developer.zendesk.com/rest_api/docs/support/locales#list-locales
 func (z *Client) GetLocales() ([]Locale, error) {
diff --git a/zendesk/mock/client.go b/zendesk/mock/client.go
new file mode 100644
index 00000000..30c384b8
--- /dev/null
+++ b/zendesk/mock/client.go
@@ -0,0 +1,219 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: github.com/nukosuke/go-zendesk/zendesk (interfaces: API)
+
+// Package mock is a generated GoMock package.
+package mock
+
+import (
+	gomock "github.com/golang/mock/gomock"
+	zendesk "github.com/nukosuke/go-zendesk/zendesk"
+	reflect "reflect"
+)
+
+// Client is a mock of API interface
+type Client struct {
+	ctrl     *gomock.Controller
+	recorder *ClientMockRecorder
+}
+
+// ClientMockRecorder is the mock recorder for Client
+type ClientMockRecorder struct {
+	mock *Client
+}
+
+// NewClient creates a new mock instance
+func NewClient(ctrl *gomock.Controller) *Client {
+	mock := &Client{ctrl: ctrl}
+	mock.recorder = &ClientMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use
+func (m *Client) EXPECT() *ClientMockRecorder {
+	return m.recorder
+}
+
+// CreateGroup mocks base method
+func (m *Client) CreateGroup(arg0 zendesk.Group) (zendesk.Group, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "CreateGroup", arg0)
+	ret0, _ := ret[0].(zendesk.Group)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// CreateGroup indicates an expected call of CreateGroup
+func (mr *ClientMockRecorder) CreateGroup(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "CreateGroup", reflect.TypeOf((*Client)(nil).CreateGroup), arg0)
+}
+
+// CreateTicketField mocks base method
+func (m *Client) CreateTicketField(arg0 zendesk.TicketField) (zendesk.TicketField, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "CreateTicketField", arg0)
+	ret0, _ := ret[0].(zendesk.TicketField)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// CreateTicketField indicates an expected call of CreateTicketField
+func (mr *ClientMockRecorder) CreateTicketField(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "CreateTicketField", reflect.TypeOf((*Client)(nil).CreateTicketField), arg0)
+}
+
+// CreateTicketForm mocks base method
+func (m *Client) CreateTicketForm(arg0 zendesk.TicketForm) (zendesk.TicketForm, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "CreateTicketForm", arg0)
+	ret0, _ := ret[0].(zendesk.TicketForm)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// CreateTicketForm indicates an expected call of CreateTicketForm
+func (mr *ClientMockRecorder) CreateTicketForm(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "CreateTicketForm", reflect.TypeOf((*Client)(nil).CreateTicketForm), arg0)
+}
+
+// CreateTrigger mocks base method
+func (m *Client) CreateTrigger(arg0 zendesk.Trigger) (zendesk.Trigger, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "CreateTrigger", arg0)
+	ret0, _ := ret[0].(zendesk.Trigger)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// CreateTrigger indicates an expected call of CreateTrigger
+func (mr *ClientMockRecorder) CreateTrigger(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "CreateTrigger", reflect.TypeOf((*Client)(nil).CreateTrigger), arg0)
+}
+
+// CreateUser mocks base method
+func (m *Client) CreateUser(arg0 zendesk.User) (zendesk.User, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "CreateUser", arg0)
+	ret0, _ := ret[0].(zendesk.User)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// CreateUser indicates an expected call of CreateUser
+func (mr *ClientMockRecorder) CreateUser(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "CreateUser", reflect.TypeOf((*Client)(nil).CreateUser), arg0)
+}
+
+// GetGroups mocks base method
+func (m *Client) GetGroups() ([]zendesk.Group, zendesk.Page, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetGroups")
+	ret0, _ := ret[0].([]zendesk.Group)
+	ret1, _ := ret[1].(zendesk.Page)
+	ret2, _ := ret[2].(error)
+	return ret0, ret1, ret2
+}
+
+// GetGroups indicates an expected call of GetGroups
+func (mr *ClientMockRecorder) GetGroups() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetGroups", reflect.TypeOf((*Client)(nil).GetGroups))
+}
+
+// GetLocales mocks base method
+func (m *Client) GetLocales() ([]zendesk.Locale, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetLocales")
+	ret0, _ := ret[0].([]zendesk.Locale)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// GetLocales indicates an expected call of GetLocales
+func (mr *ClientMockRecorder) GetLocales() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetLocales", reflect.TypeOf((*Client)(nil).GetLocales))
+}
+
+// GetTicketField mocks base method
+func (m *Client) GetTicketField(arg0 int64) (zendesk.TicketField, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetTicketField", arg0)
+	ret0, _ := ret[0].(zendesk.TicketField)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// GetTicketField indicates an expected call of GetTicketField
+func (mr *ClientMockRecorder) GetTicketField(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetTicketField", reflect.TypeOf((*Client)(nil).GetTicketField), arg0)
+}
+
+// GetTicketFields mocks base method
+func (m *Client) GetTicketFields() ([]zendesk.TicketField, zendesk.Page, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetTicketFields")
+	ret0, _ := ret[0].([]zendesk.TicketField)
+	ret1, _ := ret[1].(zendesk.Page)
+	ret2, _ := ret[2].(error)
+	return ret0, ret1, ret2
+}
+
+// GetTicketFields indicates an expected call of GetTicketFields
+func (mr *ClientMockRecorder) GetTicketFields() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetTicketFields", reflect.TypeOf((*Client)(nil).GetTicketFields))
+}
+
+// GetTicketForms mocks base method
+func (m *Client) GetTicketForms() ([]zendesk.TicketForm, zendesk.Page, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetTicketForms")
+	ret0, _ := ret[0].([]zendesk.TicketForm)
+	ret1, _ := ret[1].(zendesk.Page)
+	ret2, _ := ret[2].(error)
+	return ret0, ret1, ret2
+}
+
+// GetTicketForms indicates an expected call of GetTicketForms
+func (mr *ClientMockRecorder) GetTicketForms() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetTicketForms", reflect.TypeOf((*Client)(nil).GetTicketForms))
+}
+
+// GetTriggers mocks base method
+func (m *Client) GetTriggers() ([]zendesk.Trigger, zendesk.Page, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetTriggers")
+	ret0, _ := ret[0].([]zendesk.Trigger)
+	ret1, _ := ret[1].(zendesk.Page)
+	ret2, _ := ret[2].(error)
+	return ret0, ret1, ret2
+}
+
+// GetTriggers indicates an expected call of GetTriggers
+func (mr *ClientMockRecorder) GetTriggers() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetTriggers", reflect.TypeOf((*Client)(nil).GetTriggers))
+}
+
+// GetUsers mocks base method
+func (m *Client) GetUsers() ([]zendesk.User, zendesk.Page, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetUsers")
+	ret0, _ := ret[0].([]zendesk.User)
+	ret1, _ := ret[1].(zendesk.Page)
+	ret2, _ := ret[2].(error)
+	return ret0, ret1, ret2
+}
+
+// GetUsers indicates an expected call of GetUsers
+func (mr *ClientMockRecorder) GetUsers() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetUsers", reflect.TypeOf((*Client)(nil).GetUsers))
+}
diff --git a/zendesk/ticket_field.go b/zendesk/ticket_field.go
index ca7271f4..4e5a6b69 100644
--- a/zendesk/ticket_field.go
+++ b/zendesk/ticket_field.go
@@ -45,6 +45,13 @@ type TicketField struct {
 	AgentDescription    string                         `json:"agent_description,omitempty"`
 }
 
+// TicketFieldAPI an interface containing all of the ticket field related zendesk methods
+type TicketFieldAPI interface {
+	GetTicketFields() ([]TicketField, Page, error)
+	CreateTicketField(ticketField TicketField) (TicketField, error)
+	GetTicketField(ticketID int64) (TicketField, error)
+}
+
 // GetTicketFields fetches ticket field list
 // ref: https://developer.zendesk.com/rest_api/docs/core/ticket_fields#list-ticket-fields
 func (z Client) GetTicketFields() ([]TicketField, Page, error) {
diff --git a/zendesk/ticket_form.go b/zendesk/ticket_form.go
index abf0a9c9..8a460e51 100644
--- a/zendesk/ticket_form.go
+++ b/zendesk/ticket_form.go
@@ -20,6 +20,12 @@ type TicketForm struct {
 	RestrictedBrandIDs []int64 `json:"restricted_brand_ids,omitempty"`
 }
 
+// TicketFormAPI an interface containing all ticket form related methods
+type TicketFormAPI interface {
+	GetTicketForms() ([]TicketForm, Page, error)
+	CreateTicketForm(ticketForm TicketForm) (TicketForm, error)
+}
+
 // GetTicketForms fetches ticket forms
 func (z Client) GetTicketForms() ([]TicketForm, Page, error) {
 	var data struct {
diff --git a/zendesk/trigger.go b/zendesk/trigger.go
index 8c7bdc08..76daefb1 100644
--- a/zendesk/trigger.go
+++ b/zendesk/trigger.go
@@ -37,6 +37,12 @@ type Trigger struct {
 	UpdatedAt   *time.Time      `json:"updated_at,omitempty"`
 }
 
+// TriggerAPI an interface containing all trigger related methods
+type TriggerAPI interface {
+	GetTriggers() ([]Trigger, Page, error)
+	CreateTrigger(trigger Trigger) (Trigger, error)
+}
+
 // GetTriggers fetch trigger list
 func (z *Client) GetTriggers() ([]Trigger, Page, error) {
 	var data struct {
diff --git a/zendesk/user.go b/zendesk/user.go
index bff0e1cf..25a30962 100644
--- a/zendesk/user.go
+++ b/zendesk/user.go
@@ -67,6 +67,12 @@ func UserRoleText(role int) string {
 	return userRoleText[role]
 }
 
+// UserAPI an interface containing all user related methods
+type UserAPI interface {
+	GetUsers() ([]User, Page, error)
+	CreateUser(user User) (User, error)
+}
+
 // GetUsers fetch user list
 func (z *Client) GetUsers() ([]User, Page, error) {
 	var data struct {