How to mock current time in elixir

Is it possible for you to make the current time an argument into the function, just like start date and end date? Then you probably wouldn’t need to mock it.

Its possible(not very good option but yes) and I think the only solution (but it will fail in some cases e.g controllers shouldn’t send current date as option to this context method. but for testing context itself it will work)

Or define your own function/service MyDateTime.utc_now/0 and mock it in your tests.

not very good option but yes
but it will fail in some cases e.g controllers shouldn’t send current date as option to this context method.

Some other function in your context can do that.

# in controller
def post(conn, params) do
  # ...
  Context.do_stuff(with: command)
  # ...
end

# in your context
def do_stuff(with: %Command{...} = command) do
  do_stuff(with: command, time: DateTime.utc_now())
end

# false, since it's used directly only in tests
@doc false
def do_stuff(with: command, time: time) do # this is what you test
  # ... your logic
end

Thank you sooo much @idi527 for giving me great options. But @nresni 's answer suits best for my needs.