defmodule Membrane.Testing.Pipeline do
@moduledoc """
This Pipeline was created to reduce testing boilerplate and ease communication
with its children. It also provides a utility for informing testing process about
playback changes and received notifications.
When you want a build Pipeline to test your children you need three things:
- Pipeline Module
- List of children
- Links between those children
To start a testing pipeline you need to build
a keyword list representing the options used to determine the pipeline's behaviour and then
pass that options list to the `Membrane.Testing.Pipeline.start_link_supervised!/1`.
The testing pipeline can be started in one of two modes - either with its `:default` behaviour, or by
injecting a custom module behaviour. The usage of a `:default` pipeline implementation is presented below:
```
links = [
child(:el1, MembraneElement1) |>
child(:el2, MembraneElement2)
...
]
options = [
module: :default # :default is the default value for this parameter, so you do not need to pass it here
spec: links
]
pipeline = Membrane.Testing.Pipeline.start_link_supervised!(options)
```
You can also pass your custom pipeline's module as a `:module` option of
the options list. Every callback of the module
will be executed before the callbacks of Testing.Pipeline.
Passed module has to return a proper spec. There should be no children
nor links specified in options passed to test pipeline as that would
result in a failure.
```
options = [
module: Your.Module
]
pipeline = Membrane.Testing.Pipeline.start_link_supervised!(options)
```
See `t:Membrane.Testing.Pipeline.options/0` for available options.
## Assertions
This pipeline is designed to work with `Membrane.Testing.Assertions`. Check
them out or see example below for more details.
## Messaging children
You can send messages to children using their names specified in the children
list. Please check `message_child/3` for more details.
## Example usage
Firstly, we can start the pipeline providing its options as a keyword list:
import Membrane.ChildrenSpec
children = [
child(source, %Membrane.Testing.Source{} ) |>
child(:tested_element, TestedElement) |>
child(sink, %Membrane.Testing.Sink{})
]
{:ok, pipeline} = Membrane.Testing.Pipeline.start_link(spec: links)
We can now wait till the end of the stream reaches the sink element (don't forget
to import `Membrane.Testing.Assertions`):
assert_end_of_stream(pipeline, :sink)
We can also assert that the `Membrane.Testing.Sink` processed a specific
buffer:
assert_sink_buffer(pipeline, :sink, %Membrane.Buffer{payload: 1})
"""
use Membrane.Pipeline
alias Membrane.Child
alias Membrane.ChildrenSpec
alias Membrane.Core.Message
alias Membrane.{Element, Pipeline}
alias Membrane.Testing.Notification
require Membrane.Core.Message
defmodule State do
@moduledoc false
@enforce_keys [:test_process, :module]
defstruct @enforce_keys ++ [:custom_pipeline_state, :raise_on_child_pad_removed?]
@typedoc """
Structure for holding state
## Test Process
`pid` of process that shall receive messages from the pipeline
## Module
Pipeline Module with custom callbacks.
## Custom Pipeline State
State of the pipeline defined by Module.
"""
@type t :: %__MODULE__{
test_process: pid() | nil,
module: module() | nil,
custom_pipeline_state: Pipeline.state(),
raise_on_child_pad_removed?: boolean() | nil
}
end
@type options ::
[
module: :default,
spec: [ChildrenSpec.builder()],
test_process: pid(),
name: Pipeline.name(),
raise_on_child_pad_removed?: boolean()
]
| [
module: module(),
custom_args: Pipeline.pipeline_options(),
test_process: pid(),
name: Pipeline.name()
]
@spec child_spec(options) :: Supervisor.child_spec()
def child_spec(options) do
id = Keyword.get(options, :name, make_ref())
super(options) |> Map.merge(%{restart: :transient, id: id})
end
@spec start_link(options) :: Pipeline.on_start()
def start_link(options) do
do_start(:start_link, options)
end
@spec start(options) :: Pipeline.on_start()
def start(options) do
do_start(:start, options)
end
defp do_start(type, options) do
options =
if Keyword.has_key?(options, :structure) do
{spec, options} = Keyword.pop(options, :structure)
[spec: spec] ++ options
else
options
end
{process_options, options} = Keyword.split(options, [:name])
options = Keyword.put_new(options, :test_process, self())
apply(Pipeline, type, [__MODULE__, options, process_options])
end
@doc """
Starts the pipeline under the ExUnit test supervisor and links it to the current process.
Can be used only in tests.
"""
@spec start_link_supervised(options) :: Pipeline.on_start()
def start_link_supervised(pipeline_options \\ []) do
pipeline_options = Keyword.put_new(pipeline_options, :test_process, self())
# TODO use start_link_supervised when added
with {:ok, supervisor, pipeline} <- ex_unit_start_supervised({__MODULE__, pipeline_options}) do
Process.link(pipeline)
{:ok, supervisor, pipeline}
else
{:error, {error, _child_info}} -> {:error, error}
end
end
@spec start_link_supervised!(options) :: pipeline_pid :: pid
def start_link_supervised!(pipeline_options \\ []) do
{:ok, _supervisor, pipeline} = start_link_supervised(pipeline_options)
pipeline
end
@doc """
Starts the pipeline under the ExUnit test supervisor.
Can be used only in tests.
"""
@spec start_supervised(options) :: Pipeline.on_start()
def start_supervised(pipeline_options \\ []) do
pipeline_options = Keyword.put_new(pipeline_options, :test_process, self())
ex_unit_start_supervised({__MODULE__, pipeline_options})
end
@spec start_supervised!(options) :: pipeline_pid :: pid
def start_supervised!(pipeline_options \\ []) do
{:ok, _supervisor, pipeline} = start_supervised(pipeline_options)
pipeline
end
defp ex_unit_start_supervised(child_spec) do
# It's not a 'normal' call to keep dialyzer quiet
apply(ExUnit.Callbacks, :start_supervised, [child_spec])
end
@doc """
Sends message to a child by Element name.
## Example
Knowing that `pipeline` has child named `sink`, message can be sent as follows:
message_child(pipeline, :sink, {:message, "to handle"})
"""
@spec message_child(pid(), Element.name(), any()) :: :ok
def message_child(pipeline, child, message) do
send(pipeline, {:for_element, child, message})
:ok
end
@doc """
Executes specified actions in the pipeline.
The actions are returned from the `handle_info` callback.
"""
@spec execute_actions(pid(), Keyword.t()) :: :ok
def execute_actions(pipeline, actions) do
send(pipeline, {__MODULE__, :__execute_actions__, actions})
:ok
end
@doc """
Returns the pid of the children process.
Accepts pipeline pid as a first argument and a child reference or a list
of child references representing a path as a second argument.
If second argument is a child reference, function gets pid of this child
from pipeline.
If second argument is a path of child references, function gets pid of
last a component pointed by this path.
Returns
* `{:ok, child_pid}`, if a child was succesfully found
* `{:error, reason}`, if, for example, pipeline is not alive or children path is invalid
"""
@spec get_child_pid(pid(), child_name_path :: Child.name() | [Child.name()]) ::
{:ok, pid()} | {:error, reason :: term()}
def get_child_pid(pipeline, [_head | _tail] = child_name_path) do
do_get_child_pid(pipeline, child_name_path)
end
def get_child_pid(pipeline, child_name) when not is_list(child_name) do
do_get_child_pid(pipeline, [child_name])
end
@doc """
Returns the pid of the children process.
Works as get_child_pid/2, but raises an error instead of returning
`{:error, reason}` tuple.
"""
@spec get_child_pid!(pid(), child_name_path :: Child.name() | [Child.name()]) :: pid()
def get_child_pid!(parent_pid, child_name_path) do
{:ok, child_pid} = get_child_pid(parent_pid, child_name_path)
child_pid
end
defp do_get_child_pid(component_pid, child_name_path, is_pipeline? \\ true)
defp do_get_child_pid(component_pid, [], _is_pipeline?) do
{:ok, component_pid}
end
defp do_get_child_pid(component_pid, [child_name | child_name_path_tail], is_pipeline?) do
case Message.call(component_pid, :get_child_pid, child_name) do
{:ok, child_pid} ->
do_get_child_pid(child_pid, child_name_path_tail, false)
{:error, {:call_failure, {:noproc, _call_info}}} ->
if is_pipeline?,
do: {:error, :pipeline_not_alive},
else: {:error, :component_not_alive}
{:error, _reason} = error ->
error
end
end
@impl true
def handle_init(ctx, options) do
case Keyword.get(options, :module, :default) do
:default ->
spec = Bunch.listify(Keyword.get(options, :spec, []))
test_process = Keyword.fetch!(options, :test_process)
raise? = Keyword.get(options, :raise_on_child_pad_removed?, true)
new_state = %State{
test_process: test_process,
raise_on_child_pad_removed?: raise?,
module: nil
}
{[spec: spec], new_state}
module when is_atom(module) ->
case Code.ensure_compiled(module) do
{:module, _} -> :ok
{:error, _} -> raise "Unknown module: #{inspect(module)}"
end
new_state = %State{
module: module,
custom_pipeline_state: Keyword.get(options, :custom_args),
test_process: Keyword.fetch!(options, :test_process)
}
injected_module_result = eval_injected_module_callback(:handle_init, [ctx], new_state)
testing_pipeline_result = {[], new_state}
combine_results(injected_module_result, testing_pipeline_result)
not_a_module ->
raise "Not a module: #{inspect(not_a_module)}"
end
end
@impl true
def handle_setup(ctx, %State{} = state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_setup,
[ctx],
state
)
:ok = notify_test_process(state.test_process, :setup)
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_playing(ctx, %State{} = state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_playing,
[ctx],
state
)
:ok = notify_test_process(state.test_process, :play)
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_child_notification(
%Notification{payload: notification},
from,
_ctx,
%State{} = state
) do
:ok =
notify_test_process(state.test_process, {:handle_child_notification, {notification, from}})
{[], state}
end
@impl true
def handle_child_notification(notification, from, ctx, %State{} = state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_child_notification,
[notification, from, ctx],
state
)
:ok =
notify_test_process(state.test_process, {:handle_child_notification, {notification, from}})
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_spec_started(children, ctx, %State{} = state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_spec_started,
[children, ctx],
state
)
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_info({__MODULE__, :__execute_actions__, actions}, _ctx, %State{} = state) do
{actions, state}
end
@impl true
def handle_info({:for_element, element, message}, ctx, %State{} = state) do
injected_module_result =
eval_injected_module_callback(
:handle_info,
[{:for_element, element, message}, ctx],
state
)
testing_pipeline_result = {[notify_child: {element, message}], state}
combine_results(injected_module_result, testing_pipeline_result)
end
@impl true
def handle_info(message, ctx, %State{} = state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_info,
[message, ctx],
state
)
:ok = notify_test_process(state.test_process, {:handle_info, message})
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_call(message, ctx, state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_call,
[message, ctx],
state
)
:ok = notify_test_process(state.test_process, {:handle_call, message})
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_element_start_of_stream(element, pad, ctx, state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_element_start_of_stream,
[element, pad, ctx],
state
)
:ok =
notify_test_process(state.test_process, {:handle_element_start_of_stream, {element, pad}})
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_element_end_of_stream(element, pad, ctx, state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_element_end_of_stream,
[element, pad, ctx],
state
)
:ok = notify_test_process(state.test_process, {:handle_element_end_of_stream, {element, pad}})
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_tick(timer, ctx, state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_tick,
[timer, ctx],
state
)
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_child_pad_removed(child, pad, ctx, state) do
if state.raise_on_child_pad_removed? do
raise """
Child #{inspect(child)} removed it's pad #{inspect(pad)}. If you want to
handle such a scenario, pass `raise_on_child_pad_removed?: false` option to
`Membrane.Testing.Pipeline.start_*/2` or pass there a pipeline module
implementing this callback via `:module` option.
"""
end
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_child_pad_removed,
[child, pad, ctx],
state
)
:ok = notify_test_process(state.test_process, {:handle_child_pad_removed, {child, pad}})
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
@impl true
def handle_crash_group_down(group_name, ctx, state) do
{custom_actions, custom_state} =
eval_injected_module_callback(
:handle_crash_group_down,
[group_name, ctx],
state
)
:ok = notify_test_process(state.test_process, {:handle_crash_group_down, group_name})
{custom_actions, Map.put(state, :custom_pipeline_state, custom_state)}
end
defp eval_injected_module_callback(callback, args, state)
defp eval_injected_module_callback(_callback, _args, %State{module: nil}),
do: {[], nil}
defp eval_injected_module_callback(callback, args, state) do
apply(state.module, callback, args ++ [state.custom_pipeline_state])
end
defp notify_test_process(test_process, message) do
send(test_process, {__MODULE__, self(), message})
:ok
end
defp combine_results({custom_actions, custom_state}, {actions, state}) do
{Enum.concat(custom_actions, actions), Map.put(state, :custom_pipeline_state, custom_state)}
end
end
