public void ShouldChangeAdminPasswordAsync() { // Arrange ISystemApi systemApi = CreateSystemApi(); // Act bool result = systemApi.ChangeAdminPasswordAsync("oldPassword", "newPassword").Result; // Assert result.ShouldBe(true); Should.Throw <ArgumentNullException>(() => systemApi.ChangeAdminPasswordAsync(null, "newPassword")); Should.Throw <ArgumentNullException>(() => systemApi.ChangeAdminPasswordAsync("oldPassword", null)); }