definject v1.1.2 Definject View Source
Link to this section Summary
Functions
definject
transforms a function to accept a map where dependent functions and modules can be injected.
Link to this section Functions
definject
transforms a function to accept a map where dependent functions and modules can be injected.
import Definject
definject send_welcome_email(user_id) do
%{email: email} = Repo.get(User, user_id)
welcome_email(to: email)
|> Mailer.send()
end
is expanded into (simplified for understanding)
def send_welcome_email(user_id, deps \\ %{}) do
%{email: email} = Map.get(deps, &Repo.get/2, &Repo.get/2).(User, user_id)
welcome_email(to: email)
|> Map.get(deps, &Mailer.send/1, &Mailer.send/1).()
end
Note that local function calls like welcome_email(to: email)
are not expanded unless it is prepended with __MODULE__
.
Now, you can inject mock functions and modules in tests.
test "send_welcome_email" do
Accounts.send_welcome_email(100, %{
Repo => MockRepo,
&Mailer.send/1 => fn %Email{to: "user100@gmail.com", subject: "Welcome"} ->
Process.send(self(), :email_sent)
end
})
assert_receive :email_sent
end
definject
raises if the passed map includes a function or a module that's not used within the injected function.
You can disable this by adding strict: false
option.
test "send_welcome_email with strict: false" do
Accounts.send_welcome_email(100, %{
&Repo.get/2 => fn User, 100 -> %User{email: "user100@gmail.com"} end,
&Repo.all/1 => fn _ -> [%User{email: "user100@gmail.com"}] end, # Unused
strict: false,
})
end
If you don't need pattern matching in mock function, mock/1
can be used to reduce boilerplates.
import Definject
test "send_welcome_email with mock/1" do
Accounts.send_welcome_email(
100,
mock(%{
Repo => MockRepo,
&Mailer.send/1 => Process.send(self(), :email_sent)
})
)
assert_receive :email_sent
end
Note that Process.send(self(), :email_sent)
is surrounded by fn _ -> end
when expanded.