Support naming a virtual channel

grpc_client/lib/grpc/client/connection.ex

@@ -153,9 +153,27 @@ defmodule GRPC.Client.Connection do
   """
   @spec connect(String.t(), keyword()) :: {:ok, Channel.t()} | {:error, any()}
   def connect(target, opts \\ []) do
-    ref = make_ref()
+    supervisor_pid = Process.whereis(GRPC.Client.Supervisor)
 
-    case build_initial_state(target, Keyword.merge(opts, ref: ref)) do
+    if is_nil(supervisor_pid) or !Process.alive?(supervisor_pid) do
+      raise """
+      GRPC.Client.Supervisor is not running. Please ensure it is started as part of your
+      application's supervision tree:
+
+          children = [
+            {GRPC.Client.Supervisor, []}
+          ]
+
+          opts = [strategy: :one_for_one, name: MyApp.Supervisor]
+          Supervisor.start_link(children, opts)
+
+      You can also start it manually in scripts or test environments:
+
+          {:ok, _pid} = DynamicSupervisor.start_link(strategy: :one_for_one, name: GRPC.Client.Supervisor)
+      """
+    end
+
+    case build_initial_state(target, opts) do
       {:ok, initial_state} ->
         ch = initial_state.virtual_channel
 
@@ -307,7 +325,7 @@ defmodule GRPC.Client.Connection do
     opts =
       Keyword.validate!(opts,
         cred: nil,
-        ref: nil,
+        name: make_ref(),
         adapter: GRPC.Client.Adapters.Gun,
         adapter_opts: [],
         interceptors: [],
@@ -333,7 +351,7 @@ defmodule GRPC.Client.Connection do
     virtual_channel = %Channel{
       scheme: scheme,
       cred: cred,
-      ref: opts[:ref],
+      ref: opts[:name],
       adapter: adapter,
       interceptors: interceptors,
       codec: norm_opts[:codec],

grpc_client/test/grpc/integration/stub_test.exs

@@ -68,6 +68,21 @@ defmodule GRPC.Integration.StubTest do
     end)
   end
 
+  test "use a channel name to send a message" do
+    run_server(HelloServer, fn port ->
+      {:ok, _channel} =
+        GRPC.Client.Connection.connect("localhost:#{port}",
+          interceptors: [GRPC.Client.Interceptors.Logger],
+          name: :my_channel
+        )
+
+      name = "GRPC user!"
+      req = %Helloworld.HelloRequest{name: name}
+      {:ok, reply} = %GRPC.Channel{ref: :my_channel} |> Helloworld.Greeter.Stub.say_hello(req)
+      assert reply.message == "Hello, #{name}"
+    end)
+  end
+
   test "invalid channel function clause error" do
     req = %Helloworld.HelloRequest{name: "GRPC"}