VSoft.System.TimeProvider
A simple abstraction over Now/NowUTC for Delphi to make unit testing date based code easier.
- Active · last change 5-25-2026
- ★ 1 on GitHub
README
VSoft.System.TimeProvider
This simple unit provides an abstraction over TDateTime.Now and TDateTime.NowUTC that makes it easier to write testable code.
Code that directly references Now or NowUTC is very difficult to unit test. Imagine you have a function that uses one of the many helper methods on TDateTime.Now, for example :
function TDiscountCalculator.GetDiscountForToday : integer;
begin
if TDateTime.Now.DayOfWeek = 3 then
result := 50
else
result := 0;
end;Unit testing this function would be impossible. As simple fix to this is to inject an abstraction over Now
function TDiscountCalculator.GetDiscountForToday(const dateTimeProvider : IDateTimeProvider) : integer;
begin
if dateTimeProvider.Now.DayOfWeek = 3 then
result := 50
else
result := 0;
end;Our ITimeProvider is mockable, so we can test this by either using a mocking framework, or providing our own implementation.
type
{$M+} //mockable
ITimeProvider = interface
['{6A876048-CA4D-47BC-93CE-E16382D43797}']
function GetLocalNow : TDateTime;
function GetUTCNow : TDateTime;
property Now : TDateTime read GetLocalNow;
property NowUTC : TDateTime read GetUTCNow;
end;
TTimeProvider = class
public
class function Default : ITimeProvider;static;
end;procedure TDiscountTestFixture.Test_Discount_is_50_on_Tuesdays;
var
discount : integer;
dateTimeProviderMock : Mock<IDateTimeProvider>;
mockNow L : TDateTime;
begin
//arrange
mockNow := EncodeDate(2025,4,1);
dateTimeProviderMock := TMock<IDateTimeProvider>.Create;
dateTimeProviderMock.Setup.WillReturn(mockNow).When.Now();
//act
discount := FDiscountCalculator.GetDiscountForToday(dateTimeProviderMock);
//assert
Assert.AreEqual(50, discount);
end;Use TTimeProvider.Default in your production code.