patch lab 03 from feedback

labs/03/arithmetic.ex

@@ -13,6 +13,8 @@ defmodule Arithmetic.Worker do
 
   @impl true
   def handle_cast({:square, x, from}, state) do
+    # The server dispatches work asynchronously, so workers handle casts and
+    # reply directly to the client that made the original GenServer.call/2.
     GenServer.reply(from, {self(), x * x})
     {:noreply, state}
   end
@@ -61,7 +63,7 @@ defmodule Arithmetic.Server do
     GenServer.cast(worker, {:square, x, from})
 
     next = rem(index + 1, length(workers))
-    # dont reply here, worker will reply
+    # Do not reply here; the selected worker replies to `from` after the cast.
     {:noreply, {workers, next}}
   end
 

labs/03/card/README.md

@@ -18,4 +18,3 @@ end
 Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
 and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
 be found at <https://hexdocs.pm/card>.
-

labs/03/card/lib/card/worker.ex

@@ -3,7 +3,7 @@ defmodule Card.Worker do
 
   ### Client API ###
   def start() do
-    GenServer.start(__MODULE__, fresh(), name: __MODULE__)
+    GenServer.start(__MODULE__, nil, name: __MODULE__)
   end
 
   def new() do
@@ -31,8 +31,8 @@ defmodule Card.Worker do
   end
 
   @impl true
-  def init(arg) do
-    {:ok, arg}
+  def init(_arg) do
+    {:ok, fresh()}
   end
 
   @impl true

labs/03/card/test/card_test.exs

@@ -1,8 +1,29 @@
 defmodule CardTest do
   use ExUnit.Case
-  doctest Card
 
-  test "greets the world" do
-    assert Card.hello() == :world
+  setup do
+    {:ok, pid} = Card.Worker.start()
+    on_exit(fn ->
+      if Process.alive?(pid), do: GenServer.stop(pid)
+    end)
+
+    :ok
+  end
+
+  test "the server creates a fresh deck when it starts" do
+    assert Card.Worker.count() == 52
+  end
+
+  test "dealing removes cards from the server's deck" do
+    assert {:ok, cards} = Card.Worker.deal(5)
+    assert length(cards) == 5
+    assert Card.Worker.count() == 47
+  end
+
+  test "new replaces the current deck with a fresh deck" do
+    assert {:ok, _cards} = Card.Worker.deal(5)
+    Card.Worker.new()
+
+    assert Card.Worker.count() == 52
   end
 end