Add another test case

lib/life/cli.ex

@@ -7,14 +7,16 @@ defmodule Life.CLI do
   def main([]) do
     loop(MapSet.new([]), @grid_size)
   end
+  def main(["glider", "--size=" <> grid_size]) do
+    loop(MapSet.new(@glider), String.to_integer(grid_size))
+  end
   def main(["glider"]) do
     loop(MapSet.new(@glider), @grid_size)
   end
   def main(["--size=" <> grid_size]) do
     loop(MapSet.new([]), String.to_integer(grid_size))
   end
 
-
   defp loop(alive_cells, grid_size, interval \\ @sleep_interval_ms) do
     alive_cells
     |> calc_grid(grid_size)

test/life/cli_test.exs

@@ -62,6 +62,16 @@ defmodule CLITest do
   ╚═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╝
   """
 
+  @grid_3x3_with_glider """
+  ╔═══╦═══╦═══╗
+  ║   ║ █ ║   ║
+  ╠═══╬═══╬═══╣
+  ║   ║   ║ █ ║
+  ╠═══╬═══╬═══╣
+  ║ █ ║ █ ║ █ ║
+  ╚═══╩═══╩═══╝
+  """
+
   test "with no args, prints an empty 10x10 grid" do
     assert @empty_grid_10x10 ==
       capture_io(fn ->
@@ -101,4 +111,17 @@ defmodule CLITest do
       end)
   end
 
+  test "with glider and --size=3 args, prints a 3x3 grid with a glider" do
+    assert @grid_3x3_with_glider ==
+      capture_io(fn ->
+        {:ok, pid} = Task.Supervisor.start_link()
+        task = Task.Supervisor.async(pid, fn ->
+          args = ["glider", "--size=3"]
+          Task.start_link(Life.CLI.main(args))
+        end)
+        :timer.sleep(1)
+        Task.shutdown(task)
+      end)
+  end
+
 end