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defmodule Phoenix.ChannelTest do
@moduledoc """
Conveniences for testing Phoenix channels.
In channel tests, we interact with channels via process
communication, sending and receiving messages. It is also
common to subscribe to the same topic the channel subscribes
to, allowing us to assert if a given message was broadcast
or not.
## Channel testing
To get started, define the module attribute `@endpoint`
in your test case pointing to your application endpoint.
Then you can directly create a socket and
`subscribe_and_join/4` topics and channels:
{:ok, _, socket} =
socket("user:id", %{some_assigns: 1})
|> subscribe_and_join(RoomChannel, "room:lobby", %{"id" => 3})
You usually want to set the same ID and assigns your
`UserSocket.connect/3` callback would set. Alternatively,
you can use the `connect/3` helper to call your `UserSocket.connect/3`
callback and initialize the socket with the socket id:
{:ok, socket} = connect(UserSocket, %{"some" => "params"}, %{})
{:ok, _, socket} = subscribe_and_join(socket, "room:lobby", %{"id" => 3})
Once called, `subscribe_and_join/4` will subscribe the
current test process to the "room:lobby" topic and start a
channel in another process. It returns `{:ok, reply, socket}`
or `{:error, reply}`.
Now, in the same way the channel has a socket representing
communication it will push to the client. Our test has a
socket representing communication to be pushed to the server.
For example, we can use the `push/3` function in the test
to push messages to the channel (it will invoke `handle_in/3`):
push(socket, "my_event", %{"some" => "data"})
Similarly, we can broadcast messages from the test itself
on the topic that both test and channel are subscribed to,
triggering `handle_out/3` on the channel:
broadcast_from(socket, "my_event", %{"some" => "data"})
> Note only `broadcast_from/3` and `broadcast_from!/3` are
available in tests to avoid broadcast messages to be resent
to the test process.
While the functions above are pushing data to the channel
(server) we can use `assert_push/3` to verify the channel
pushed a message to the client:
assert_push "my_event", %{"some" => "data"}
Or even assert something was broadcast into pubsub:
assert_broadcast "my_event", %{"some" => "data"}
Finally, every time a message is pushed to the channel,
a reference is returned. We can use this reference to
assert a particular reply was sent from the server:
ref = push(socket, "counter", %{})
assert_reply ref, :ok, %{"counter" => 1}
## Checking side-effects
Often one may want to do side-effects inside channels,
like writing to the database, and verify those side-effects
during their tests.
Imagine the following `handle_in/3` inside a channel:
def handle_in("publish", %{"id" => id}, socket) do
Repo.get!(Post, id) |> Post.publish() |> Repo.update!()
{:noreply, socket}
end
Because the whole communication is asynchronous, the
following test would be very brittle:
push(socket, "publish", %{"id" => 3})
assert Repo.get_by(Post, id: 3, published: true)
The issue is that we have no guarantees the channel has
done processing our message after calling `push/3`. The
best solution is to assert the channel sent us a reply
before doing any other assertion. First change the
channel to send replies:
def handle_in("publish", %{"id" => id}, socket) do
Repo.get!(Post, id) |> Post.publish() |> Repo.update!()
{:reply, :ok, socket}
end
Then expect them in the test:
ref = push(socket, "publish", %{"id" => 3})
assert_reply ref, :ok
assert Repo.get_by(Post, id: 3, published: true)
## Leave and close
This module also provides functions to simulate leaving
and closing a channel. Once you leave or close a channel,
because the channel is linked to the test process on join,
it will crash the test process:
leave(socket)
** (EXIT from #PID<...>) {:shutdown, :leave}
You can avoid this by unlinking the channel process in
the test:
Process.unlink(socket.channel_pid)
Notice `leave/1` is async, so it will also return a
reference which you can use to check for a reply:
ref = leave(socket)
assert_reply ref, :ok
On the other hand, close is always sync and it will
return only after the channel process is guaranteed to
have been terminated:
:ok = close(socket)
This mimics the behaviour existing in clients.
To assert that your channel closes or errors asynchronously,
you can monitor the channel process with the tools provided
by Elixir, and wait for the `:DOWN` message.
Imagine an implementation of the `handle_info/2` function
that closes the channel when it receives `:some_message`:
def handle_info(:some_message, socket) do
{:stop, :normal, socket}
end
In your test, you can assert that the close happened by:
Process.monitor(socket.channel_pid)
send(socket.channel_pid, :some_message)
assert_receive {:DOWN, _, _, _, :normal}
"""
alias Phoenix.Socket
alias Phoenix.Socket.{Broadcast, Message, Reply}
alias Phoenix.Channel.Server
defmodule NoopSerializer do
@behaviour Phoenix.Socket.Serializer
@moduledoc false
def fastlane!(%Broadcast{} = msg) do
%Message{
topic: msg.topic,
event: msg.event,
payload: msg.payload
}
end
def encode!(%Reply{} = reply), do: reply
def encode!(%Message{} = msg), do: msg
def decode!(message, _opts), do: message
end
@doc false
defmacro __using__(_) do
quote do
import Phoenix.ChannelTest
end
end
@doc """
Builds a socket for the given `socket_module`.
The socket is then used to subscribe and join channels.
Use this function when you want to create a blank socket
to pass to functions like `UserSocket.connect/3`.
Otherwise, use `socket/3` if you want to build a socket with
existing id and assigns.
## Examples
socket(MyApp.UserSocket)
"""
defmacro socket(socket_module) do
build_socket(socket_module, nil, [], __CALLER__)
end
@doc """
Builds a socket for the given `socket_module` with given id and assigns.
## Examples
socket(MyApp.UserSocket, "user_id", %{some: :assign})
"""
defmacro socket(socket_module, socket_id, socket_assigns) do
build_socket(socket_module, socket_id, socket_assigns, __CALLER__)
end
defp build_socket(socket, id, assigns, caller) do
if endpoint = Module.get_attribute(caller.module, :endpoint) do
quote do
%Socket{
assigns: Enum.into(unquote(assigns), %{}),
endpoint: unquote(endpoint),
handler: unquote(socket || first_socket!(endpoint)),
id: unquote(id),
pubsub_server: unquote(endpoint).__pubsub_server__(),
serializer: NoopSerializer,
transport: :channel_test,
transport_pid: self()
}
end
else
raise "module attribute @endpoint not set for socket/2"
end
end
@doc false
defmacro socket() do
IO.warn "Phoenix.ChannelTest.socket/0 is deprecated, please call socket/1 instead"
build_socket(nil, nil, [], __CALLER__)
end
@doc false
defmacro socket(id, assigns) do
IO.warn "Phoenix.ChannelTest.socket/2 is deprecated, please call socket/3 instead"
build_socket(nil, id, assigns, __CALLER__)
end
# TODO v2: Remove this alongside the deprecations above.
defp first_socket!(endpoint) do
case endpoint.__sockets__ do
[] -> raise ArgumentError, "#{inspect endpoint} has no socket declaration"
[{_, socket, _} | _] -> socket
end
end
@doc """
Initiates a transport connection for the socket handler.
Useful for testing UserSocket authentication. Returns
the result of the handler's `connect/3` callback.
"""
defmacro connect(handler, params, connect_info \\ quote(do: %{})) do
if endpoint = Module.get_attribute(__CALLER__.module, :endpoint) do
quote do
unquote(__MODULE__).__connect__(unquote(endpoint), unquote(handler), unquote(params), unquote(connect_info))
end
else
raise "module attribute @endpoint not set for socket/2"
end
end
@doc false
def __connect__(endpoint, handler, params, connect_info) do
map = %{
endpoint: endpoint,
transport: :channel_test,
options: [serializer: [{NoopSerializer, "~> 1.0.0"}]],
params: __stringify__(params),
connect_info: connect_info
}
with {:ok, state} <- handler.connect(map),
{:ok, {_, socket}} = handler.init(state),
do: {:ok, socket}
end
@doc "See `subscribe_and_join!/4`."
def subscribe_and_join!(%Socket{} = socket, topic) when is_binary(topic) do
subscribe_and_join!(socket, nil, topic, %{})
end
@doc "See `subscribe_and_join!/4`."
def subscribe_and_join!(%Socket{} = socket, topic, payload)
when is_binary(topic) and is_map(payload) do
subscribe_and_join!(socket, nil, topic, payload)
end
@doc """
Same as `subscribe_and_join/4`, but returns either the socket
or throws an error.
This is helpful when you are not testing joining the channel
and just need the socket.
"""
def subscribe_and_join!(%Socket{} = socket, channel, topic, payload \\ %{})
when is_atom(channel) and is_binary(topic) and is_map(payload) do
case subscribe_and_join(socket, channel, topic, payload) do
{:ok, _, socket} -> socket
{:error, error} -> raise "could not join channel, got error: #{inspect(error)}"
end
end
@doc "See `subscribe_and_join/4`."
def subscribe_and_join(%Socket{} = socket, topic) when is_binary(topic) do
subscribe_and_join(socket, nil, topic, %{})
end
@doc "See `subscribe_and_join/4`."
def subscribe_and_join(%Socket{} = socket, topic, payload)
when is_binary(topic) and is_map(payload) do
subscribe_and_join(socket, nil, topic, payload)
end
@doc """
Subscribes to the given topic and joins the channel
under the given topic and payload.
By subscribing to the topic, we can use `assert_broadcast/3`
to verify a message has been sent through the pubsub layer.
By joining the channel, we can interact with it directly.
The given channel is joined in a separate process which is
linked to the test process.
If no channel module is provided, the socket's handler is used to
lookup the matching channel for the given topic.
It returns `{:ok, reply, socket}` or `{:error, reply}`.
"""
def subscribe_and_join(%Socket{} = socket, channel, topic, payload \\ %{})
when is_atom(channel) and is_binary(topic) and is_map(payload) do
socket.endpoint.subscribe(topic)
join(socket, channel, topic, payload)
end
@doc "See `join/4`."
def join(%Socket{} = socket, topic) when is_binary(topic) do
join(socket, nil, topic, %{})
end
@doc "See `join/4`."
def join(%Socket{} = socket, topic, payload) when is_binary(topic) and is_map(payload) do
join(socket, nil, topic, payload)
end
@doc """
Joins the channel under the given topic and payload.
The given channel is joined in a separate process
which is linked to the test process.
It returns `{:ok, reply, socket}` or `{:error, reply}`.
"""
def join(%Socket{} = socket, channel, topic, payload \\ %{})
when is_atom(channel) and is_binary(topic) and is_map(payload) do
message = %Message{
event: "phx_join",
payload: payload,
topic: topic,
ref: System.unique_integer([:positive])
}
{channel, opts} =
if channel do
{channel, []}
else
match_topic_to_channel!(socket, topic)
end
case Server.join(socket, channel, message, opts) do
{:ok, reply, pid} ->
Process.link(pid)
{:ok, reply, Server.socket(pid)}
{:error, _} = error ->
error
end
end
@doc """
Pushes a message into the channel.
The triggers the `handle_in/3` callback in the channel.
## Examples
iex> push(socket, "new_message", %{id: 1, content: "hello"})
reference
"""
@spec push(Socket.t, String.t, map()) :: reference()
def push(socket, event, payload \\ %{}) do
ref = make_ref()
send(socket.channel_pid,
%Message{event: event, topic: socket.topic, ref: ref, payload: __stringify__(payload)})
ref
end
@doc """
Emulates the client leaving the channel.
"""
@spec leave(Socket.t) :: reference()
def leave(socket) do
push(socket, "phx_leave", %{})
end
@doc """
Emulates the client closing the socket.
Closing socket is synchronous and has a default timeout
of 5000 milliseconds.
"""
def close(socket, timeout \\ 5000) do
Server.close([socket.channel_pid], timeout)
end
@doc """
Broadcast event from pid to all subscribers of the socket topic.
The test process will not receive the published message. This triggers
the `handle_out/3` callback in the channel.
## Examples
iex> broadcast_from(socket, "new_message", %{id: 1, content: "hello"})
:ok
"""
def broadcast_from(socket, event, message) do
%{pubsub_server: pubsub_server, topic: topic, transport_pid: transport_pid} = socket
Server.broadcast_from pubsub_server, transport_pid, topic, event, message
end
@doc """
Same as `broadcast_from/3`, but raises if broadcast fails.
"""
def broadcast_from!(socket, event, message) do
%{pubsub_server: pubsub_server, topic: topic, transport_pid: transport_pid} = socket
Server.broadcast_from! pubsub_server, transport_pid, topic, event, message
end
@doc """
Asserts the channel has pushed a message back to the client
with the given event and payload within `timeout`.
Notice event and payload are patterns. This means one can write:
assert_push "some_event", %{"data" => _}
In the assertion above, we don't particularly care about
the data being sent, as long as something was sent.
The timeout is in milliseconds and defaults to the `:assert_receive_timeout`
set on the `:ex_unit` application (which defaults to 100ms).
**NOTE:** Because event and payload are patterns, they will be matched. This
means that if you wish to assert that the received payload is equivalent to
an existing variable, you need to pin the variable in the assertion
expression.
Good:
expected_payload = %{foo: "bar"}
assert_push "some_event", ^expected_payload
Bad:
expected_payload = %{foo: "bar"}
assert_push "some_event", expected_payload
# The code above does not assert the payload matches the described map.
"""
defmacro assert_push(event, payload, timeout \\ Application.fetch_env!(:ex_unit, :assert_receive_timeout)) do
quote do
assert_receive %Phoenix.Socket.Message{
event: unquote(event),
payload: unquote(payload)}, unquote(timeout)
end
end
@doc """
Asserts the channel has not pushed a message to the client
matching the given event and payload within `timeout`.
Like `assert_push`, the event and payload are patterns.
The timeout is in milliseconds and defaults to the `:refute_receive_timeout`
set on the `:ex_unit` application (which defaults to 100ms).
Keep in mind this macro will block the test by the
timeout value, so use it only when necessary as overuse
will certainly slow down your test suite.
"""
defmacro refute_push(event, payload, timeout \\ Application.fetch_env!(:ex_unit, :refute_receive_timeout)) do
quote do
refute_receive %Phoenix.Socket.Message{
event: unquote(event),
payload: unquote(payload)}, unquote(timeout)
end
end
@doc """
Asserts the channel has replied to the given message within
`timeout`.
Notice status and payload are patterns. This means one can write:
ref = push(channel, "some_event")
assert_reply ref, :ok, %{"data" => _}
In the assertion above, we don't particularly care about
the data being sent, as long as something was replied.
The timeout is in milliseconds and defaults to the `:assert_receive_timeout`
set on the `:ex_unit` application (which defaults to 100ms).
"""
defmacro assert_reply(ref, status, payload \\ Macro.escape(%{}), timeout \\ Application.fetch_env!(:ex_unit, :assert_receive_timeout)) do
quote do
ref = unquote(ref)
assert_receive %Phoenix.Socket.Reply{
ref: ^ref,
status: unquote(status),
payload: unquote(payload)}, unquote(timeout)
end
end
@doc """
Asserts the channel has not replied with a matching payload within
`timeout`.
Like `assert_reply`, the event and payload are patterns.
The timeout is in milliseconds and defaults to the `:refute_receive_timeout`
set on the `:ex_unit` application (which defaults to 100ms).
Keep in mind this macro will block the test by the
timeout value, so use it only when necessary as overuse
will certainly slow down your test suite.
"""
defmacro refute_reply(ref, status, payload \\ Macro.escape(%{}), timeout \\ Application.fetch_env!(:ex_unit, :refute_receive_timeout)) do
quote do
ref = unquote(ref)
refute_receive %Phoenix.Socket.Reply{
ref: ^ref,
status: unquote(status),
payload: unquote(payload)}, unquote(timeout)
end
end
@doc """
Asserts the channel has broadcast a message within `timeout`.
Before asserting anything was broadcast, we must first
subscribe to the topic of the channel in the test process:
@endpoint.subscribe("foo:ok")
Now we can match on event and payload as patterns:
assert_broadcast "some_event", %{"data" => _}
In the assertion above, we don't particularly care about
the data being sent, as long as something was sent.
The timeout is in milliseconds and defaults to the `:assert_receive_timeout`
set on the `:ex_unit` application (which defaults to 100ms).
"""
defmacro assert_broadcast(event, payload, timeout \\ Application.fetch_env!(:ex_unit, :assert_receive_timeout)) do
quote do
assert_receive %Phoenix.Socket.Broadcast{event: unquote(event),
payload: unquote(payload)}, unquote(timeout)
end
end
@doc """
Asserts the channel has not broadcast a message within `timeout`.
Like `assert_broadcast`, the event and payload are patterns.
The timeout is in milliseconds and defaults to the `:refute_receive_timeout`
set on the `:ex_unit` application (which defaults to 100ms).
Keep in mind this macro will block the test by the
timeout value, so use it only when necessary as overuse
will certainly slow down your test suite.
"""
defmacro refute_broadcast(event, payload, timeout \\ Application.fetch_env!(:ex_unit, :refute_receive_timeout)) do
quote do
refute_receive %Phoenix.Socket.Broadcast{event: unquote(event),
payload: unquote(payload)}, unquote(timeout)
end
end
defp match_topic_to_channel!(socket, topic) do
unless socket.handler do
raise """
no socket handler found to lookup channel for topic #{inspect topic}.
Use connect/3 when calling subscribe_and_join/* (or subscribe_and_join!/*)
without a channel, for example:
{:ok, socket} = connect(UserSocket, %{}, %{})
socket = subscribe_and_join!(socket, "foo:bar", %{})
"""
end
case socket.handler.__channel__(topic) do
{channel, opts} when is_atom(channel) -> {channel, opts}
_ -> raise "no channel found for topic #{inspect topic} in #{inspect socket.handler}"
end
end
@doc false
def __stringify__(%{__struct__: _} = struct),
do: struct
def __stringify__(%{} = params),
do: Enum.into(params, %{}, &stringify_kv/1)
def __stringify__(other),
do: other
defp stringify_kv({k, v}),
do: {to_string(k), __stringify__(v)}
end