Ensure 1 GRPC.Client.Supervisor (#466)

* Ensure 1 GRPC.Client.Supervisor

* Update lib/grpc/client/supervisor.ex

* Format code - verify author

---------

Co-authored-by: Micah Cooper <micah.cooper@mimic.com>
Co-authored-by: Adriano Santos <solid.sistemas@gmail.com>
Co-authored-by: Micah Cooper <mrmichacooper@gmail.com>

Author: 4 people

lib/grpc/client/supervisor.ex

@@ -44,7 +44,16 @@ defmodule GRPC.Client.Supervisor do
   use DynamicSupervisor
 
   def start_link(opts) do
-    DynamicSupervisor.start_link(__MODULE__, opts, name: __MODULE__)
+    case DynamicSupervisor.start_link(__MODULE__, opts, name: __MODULE__) do
+      {:ok, _pid} = started ->
+        started
+
+      {:error, {:already_started, pid}} ->
+        {:ok, pid}
+
+      other ->
+        other
+    end
   end
 
   @impl true

test/grpc/client/supervisor_test.exs

@@ -0,0 +1,14 @@
+defmodule GRPC.Client.SupervisorTest do
+  use ExUnit.Case, async: false
+
+  alias GRPC.Client
+
+  describe "start_link/1" do
+    test "allows multiple start_links" do
+      {:ok, second_pid} = Client.Supervisor.start_link([])
+      {:ok, third_pid} = Client.Supervisor.start_link([])
+
+      assert second_pid == third_pid
+    end
+  end
+end