double v0.6.5 Double
Double builds on-the-fly injectable dependencies for your tests. It does NOT override behavior of existing modules or functions. Double uses Elixir’s built-in language features such as pattern matching and message passing to give you everything you would normally need a complex mocking tool for.
Summary
Functions
Adds a stubbed function to the given map, struct, or module. Structs will fail if they are missing the key given for function_name. Modules will fail if the function is not defined
Clears stubbed functions from a double. By passing no arguments (or nil) all functions will be cleared. A single function name (atom) or a list of function names can also be given
Returns a map that can be used to setup stubbed functions
Same as double/0 but can return structs and modules too
Invoked when the server is started. start_link/3
or start/3
will
block until it returns
Types
allow_option :: {:with, [...]} | {:returns, any} | {:raises, String.t | {atom, String.t}}
Functions
Adds a stubbed function to the given map, struct, or module. Structs will fail if they are missing the key given for function_name. Modules will fail if the function is not defined.
allow(any, atom, function | [allow_option]) :: struct | map | atom
Clears stubbed functions from a double. By passing no arguments (or nil) all functions will be cleared. A single function name (atom) or a list of function names can also be given.
double(atom, [double_option]) :: atom
double(struct, [double_option]) :: struct
Same as double/0 but can return structs and modules too
Invoked when the server is started. start_link/3
or start/3
will
block until it returns.
args
is the argument term (second argument) passed to start_link/3
.
Returning {:ok, state}
will cause start_link/3
to return
{:ok, pid}
and the process to enter its loop.
Returning {:ok, state, timeout}
is similar to {:ok, state}
except handle_info(:timeout, state)
will be called after timeout
milliseconds if no messages are received within the timeout.
Returning {:ok, state, :hibernate}
is similar to
{:ok, state}
except the process is hibernated before entering the loop. See
c:handle_call/3
for more information on hibernation.
Returning :ignore
will cause start_link/3
to return :ignore
and the
process will exit normally without entering the loop or calling c:terminate/2
.
If used when part of a supervision tree the parent supervisor will not fail
to start nor immediately try to restart the GenServer
. The remainder of the
supervision tree will be (re)started and so the GenServer
should not be
required by other processes. It can be started later with
Supervisor.restart_child/2
as the child specification is saved in the parent
supervisor. The main use cases for this are:
- The
GenServer
is disabled by configuration but might be enabled later. - An error occurred and it will be handled by a different mechanism than the
Supervisor
. Likely this approach involves callingSupervisor.restart_child/2
after a delay to attempt a restart.
Returning {:stop, reason}
will cause start_link/3
to return
{:error, reason}
and the process to exit with reason reason
without
entering the loop or calling c:terminate/2
.
Callback implementation for GenServer.init/1
.