CODEWITHSUNDEEP
elixirerlang-otperlang-supervisor
The_Lost_Avatar
The_Lost_Avatar

Reputation: 990

Add a child to a Dynamic Supervisor in Elixir

I am trying to create a DynamicSupervisor to supervise another GenServer on request to it and then trying to test it.

Here is my code for NodeDynamicSupervisor:

defmodule NodeDynamicSupervisor do
  use DynamicSupervisor

  def start_link() do
    DynamicSupervisor.start_link(__MODULE__, :ok, name: __MODULE__)
  end

  def init(:ok) do
    DynamicSupervisor.init(strategy: :one_for_one)
  end

  def add_node(private_key, public_key, address, num_of_coins) do
    child_spec = {Node, {private_key, public_key, address, num_of_coins}}
    DynamicSupervisor.start_child(__MODULE__, child_spec)
  end
end

Here's how I'm testing it:

defmodule NodeCreationTest do
  use ExUnit.Case
  import ExUnit.CaptureIO

  test "should create node" do
    {:ok, node_pid} = NodeDynamicSupervisor.start_link()
    capture_io(node_pid.add_node(private_key, public_key, address, 0))
  end 
end

And this is the error I get:

 code: capture_io(node_pid.add_node(private_key, public_key, address, 0))
 stacktrace:
   :erlang.apply(#PID<0.163.0>, :add_node, [])
   test/create_nodes_test.exs:12: (test)

Why am I not able to add a node and getting this error instead?

Upvotes: 1

Views: 738

Answers (1)

Sheharyar
Sheharyar

Reputation: 75750

There are two issues with your code:

1. You can't call methods on a pid:

You're calling node_pid.add_node(...) in your test which is incorrect, when you should be calling the function from the module. Since your DynamicSupervisor process is named (name: __MODULE__) and your add_node/4 is already passing the process pid/name in the implementation, you can just call it directly:

NodeDynamicSupervisor.add_node(private_key, public_key, address, 0)

2. capture_io takes a function as the argument:

In your case you're first calling the function and passing its result to the method. You need to call the method inside an anonymous function and pass that to capture_io/1 instead:

capture_io(fn ->
  NodeDynamicSupervisor.add_node(private_key, public_key, address, 0)
end)

Upvotes: 3

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