public void DbSettingTest()
        {
            // Arrange
            var mockDependency = new Mock <ISettingsRepository>();

            mockDependency.Setup(x => x.Get()).Returns(() => new List <SettingsDb>
            {
                new SettingsDb()
                {
                    EmailHost     = "host",
                    EmailPort     = 443,
                    EmailUsername = "******",
                    EmailPassword = "******",
                    Email         = "*****@*****.**",
                    EmailFromName = "test",
                    EmailSubjectGroupInvitation = "subject",
                    EmailBodyGroupInvitation    = "<html></html>"
                }
            });

            // Act
            var mailClass = new MailClass()
            {
                SettingsRepository = mockDependency.Object
            };

            // Assert
            var res = mailClass?.GetSettings();

            if (res != null)
            {
                Assert.AreEqual("host", res.EmailHost);
                Assert.AreNotEqual(423, res.EmailPort);
                Assert.NotNull(res.Email);
                Assert.AreEqual("*****@*****.**", res.Email);

                Assert.AreEqual("test", res.EmailFromName);
                Assert.AreEqual("<html></html>", res.EmailBodyGroupInvitation);
            }
            else
            {
                Assert.AreEqual(1, 2);
            }
        }