chore(all): return concrete types, accept interfaces

- Remove exported interfaces unused locally
- Define interfaces to accept arguments
- Return concrete types, not interfaces

internal/provider/ivpn/updater/servers_test.go

@@ -25,7 +25,7 @@ func Test_Updater_GetServers(t *testing.T) {
 		minServers int
 
 		// Mocks
-		warnerBuilder func(ctrl *gomock.Controller) Warner
+		warnerBuilder func(ctrl *gomock.Controller) common.Warner
 
 		// From API
 		responseBody   string
@@ -43,12 +43,12 @@ func Test_Updater_GetServers(t *testing.T) {
 		err     error
 	}{
 		"http response error": {
-			warnerBuilder:  func(ctrl *gomock.Controller) Warner { return nil },
+			warnerBuilder:  func(ctrl *gomock.Controller) common.Warner { return nil },
 			responseStatus: http.StatusNoContent,
 			err:            errors.New("failed fetching API: HTTP status code not OK: 204 No Content"),
 		},
 		"resolve error": {
-			warnerBuilder: func(ctrl *gomock.Controller) Warner {
+			warnerBuilder: func(ctrl *gomock.Controller) common.Warner {
 				warner := NewMockWarner(ctrl)
 				warner.EXPECT().Warn("resolve warning")
 				return warner
@@ -65,7 +65,7 @@ func Test_Updater_GetServers(t *testing.T) {
 		},
 		"not enough servers": {
 			minServers:    2,
-			warnerBuilder: func(ctrl *gomock.Controller) Warner { return nil },
+			warnerBuilder: func(ctrl *gomock.Controller) common.Warner { return nil },
 			responseBody: `{"servers":[
 				{"hostnames":{"openvpn":"hosta"}}
 			]}`,
@@ -74,7 +74,7 @@ func Test_Updater_GetServers(t *testing.T) {
 		},
 		"success": {
 			minServers: 1,
-			warnerBuilder: func(ctrl *gomock.Controller) Warner {
+			warnerBuilder: func(ctrl *gomock.Controller) common.Warner {
 				warner := NewMockWarner(ctrl)
 				warner.EXPECT().Warn("resolve warning")
 				return warner

internal/provider/ivpn/updater/updater.go

@@ -9,14 +9,10 @@ import (
 type Updater struct {
 	client    *http.Client
 	presolver common.ParallelResolver
-	warner    Warner
+	warner    common.Warner
 }
 
-type Warner interface {
-	Warn(s string)
-}
-
-func New(client *http.Client, warner Warner) *Updater {
+func New(client *http.Client, warner common.Warner) *Updater {
 	return &Updater{
 		client:    client,
 		presolver: newParallelResolver(),