add CreateDirectChannel plugin api (#9848)

app/plugin_api.go

@@ -523,6 +523,25 @@ func (api *PluginAPI) RemoveTeamIcon(teamId string) *model.AppError {
 	return nil
 }
 
+func (api *PluginAPI) CreateDirectChannel(userId1 string, userId2 string) (*model.Channel, *model.AppError) {
+	_, err := api.app.GetUser(userId1)
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = api.app.GetUser(userId2)
+	if err != nil {
+		return nil, err
+	}
+
+	dm, err := api.app.CreateDirectChannel(userId1, userId2)
+	if err != nil {
+		return nil, err
+	}
+
+	return dm, nil
+}
+
 // Plugin Section
 
 func (api *PluginAPI) GetPlugins() ([]*model.Manifest, *model.AppError) {

app/plugin_api_test.go

@@ -509,3 +509,21 @@ func TestPluginAPIRemoveTeamIcon(t *testing.T) {
 	err = api.RemoveTeamIcon(th.BasicTeam.Id)
 	require.Nil(t, err)
 }
+
+func TestPluginAPICreateDirectChannel(t *testing.T) {
+	th := Setup().InitBasic()
+	defer th.TearDown()
+	api := th.SetupPluginAPI()
+
+	dm1, err := api.CreateDirectChannel(th.BasicUser.Id, th.BasicUser2.Id)
+	require.Nil(t, err)
+	require.NotEmpty(t, dm1)
+
+	dm2, err := api.CreateDirectChannel(th.BasicUser.Id, th.BasicUser.Id)
+	require.Nil(t, err)
+	require.NotEmpty(t, dm2)
+
+	dm3, err := api.CreateDirectChannel(th.BasicUser.Id, model.NewId())
+	require.NotNil(t, err)
+	require.Empty(t, dm3)
+}