I want to simulate DateTime. Let's say I have list of actions to perform, and each action has a datetime field. When that dateTime comes, the action should be performed.
I can check the datetime with DateTime.Now, but how can I simulate DateTime? I mean If the current time is 2pm. And the action should run at 4pm, 5pm. Can I use a simulate current time to 4pm and the first action will be performed and an hour later the second action will be performed?
The simplest way to achieve this is to change your system clock to the 'test time', run the test, and then change back. That's pretty hacky and I don't really recommend it, but it will work.
A better way will be to use an abstraction over DateTime.Now which will allow you to inject either a static value or manipulate the retrieved value for testing. Given that you want the test value to 'tick', rather than remain a static snapshot, it's going to be easiest to add a TimeSpan to 'now'.
So add a application setting called 'offset' that can be parsed as a TimeSpan
<appSettings>
<add key="offset" value="00:00:00" />
</appSettings>
and then add this value to your DateTime.Now every time you retrieve it.
public DateTime Time
{
get
{
var offset = TimeSpan.Parse(ConfigurationManager.AppSettings["offset"]);
return DateTime.Now + offset;
}
}
To run this one hour and twenty minutes in the future you simply adjust the offset value
<add key="offset" value="01:20:00" />
Ideally you'd create an interface for a DateTime and implement dependency injection, but for your purpose - although that would be preferred - I suggest that the can of worms that this opens will create a world of confusion for you. This is simple and will work.