diff --git a/lib/life/cli.ex b/lib/life/cli.ex
index 89ef3f9..9a625bb 100644
--- a/lib/life/cli.ex
+++ b/lib/life/cli.ex
@@ -2,37 +2,36 @@ defmodule Life.CLI do
 
   @grid_size 10
   @sleep_interval_ms 300
-
+  @glider [{1, 0}, {2, 1}, {0, 2}, {1, 2}, {2, 2}]
 
   def main([]) do
-    "no life"
+    loop(MapSet.new([]), @grid_size)
   end
   def main(["glider"]) do
-    [{3, 0}, {4, 1}, {2, 2}, {3, 2}, {4, 2}]
-    |> MapSet.new()
-    |> loop()
+    loop(MapSet.new(@glider), @grid_size)
+  end
+  def main(["--size=" <> grid_size]) do
+    loop(MapSet.new([]), String.to_integer(grid_size))
   end
 
 
-  def loop(alive_cells, interval \\ @sleep_interval_ms) do
+  defp loop(alive_cells, grid_size, interval \\ @sleep_interval_ms) do
     alive_cells
-    |> calc_grid()
+    |> calc_grid(grid_size)
     |> Table.print()
 
     :timer.sleep(interval)
 
     alive_cells
     |> Life.tick()
-    |> loop()
+    |> loop(grid_size)
   end
 
-
-  def calc_grid(alive_cells, size \\ @grid_size) do
+  # returns a 2d list. true for alive cells, false for dead
+  defp calc_grid(alive_cells, size) do
     for i <- 0..(size - 1) do
       for j <- 0..(size - 1) do
-        a = for {^j, ^i} <- alive_cells do
-          true
-        end
+        a = for {^j, ^i} <- alive_cells, do: true
         case a do
           [] -> false
           [_] -> true
diff --git a/test/life/cli_test.exs b/test/life/cli_test.exs
index c952874..9417257 100644
--- a/test/life/cli_test.exs
+++ b/test/life/cli_test.exs
@@ -2,8 +2,33 @@ defmodule CLITest do
   use ExUnit.Case
   import ExUnit.CaptureIO
 
-  # credits to this website for the ASCII table: http://www.tablesgenerator.com/text_tables
-  @empty_grid """
+  # Credits for the ASCII tables: http://www.tablesgenerator.com/text_tables
+
+  @empty_grid_10x10 """
+  ╔═══╦═══╦═══╦═══╦═══╦═══╦═══╦═══╦═══╦═══╗
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╚═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╝
+  """
+
+  @empty_grid_3x3 """
   ╔═══╦═══╦═══╗
   ║   ║   ║   ║
   ╠═══╬═══╬═══╣
@@ -13,31 +38,67 @@ defmodule CLITest do
   ╚═══╩═══╩═══╝
   """
 
-  @grid_with_glider """
-  ╔═══╦═══╦═══╗
-  ║   ║ █ ║   ║
-  ╠═══╬═══╬═══╣
-  ║   ║   ║ █ ║
-  ╠═══╬═══╬═══╣
-  ║ █ ║ █ ║ █ ║
-  ╚═══╩═══╩═══╝
+  @grid_10x10_with_glider """
+  ╔═══╦═══╦═══╦═══╦═══╦═══╦═══╦═══╦═══╦═══╗
+  ║   ║ █ ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║ █ ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║ █ ║ █ ║ █ ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╠═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╬═══╣
+  ║   ║   ║   ║   ║   ║   ║   ║   ║   ║   ║
+  ╚═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╩═══╝
   """
 
-  @tag :skip
-  test "prints an empty 3x3 grid" do
-    assert @empty_grid ==
+  test "with no args, prints an empty 10x10 grid" do
+    assert @empty_grid_10x10 ==
       capture_io(fn ->
-        assert :ok == Life.CLI.main([])
+        {:ok, pid} = Task.Supervisor.start_link()
+        task = Task.Supervisor.async(pid, fn ->
+          args = []
+          Task.start_link(Life.CLI.main(args))
+        end)
+        :timer.sleep(1)
+        Task.shutdown(task)
       end)
   end
 
-  @tag :skip
-  test "prints a 3x3 grid with a glider" do
-    grid = [{1, 0}, {2, 1}, {0, 2}, {1, 2}, {2, 2}]
+  test "with --size=3 arg, prints an empty 3x3 grid" do
+    assert @empty_grid_3x3 ==
+      capture_io(fn ->
+        {:ok, pid} = Task.Supervisor.start_link()
+        task = Task.Supervisor.async(pid, fn ->
+          args = ["--size=3"]
+          Task.start_link(Life.CLI.main(args))
+        end)
+        :timer.sleep(1)
+        Task.shutdown(task)
+      end)
+  end
 
-    assert @grid_with_glider ==
+  test "with glider arg, prints a 10x10 with a glider in the top-left corner" do
+    assert @grid_10x10_with_glider ==
       capture_io(fn ->
-        assert :ok == Life.CLI.print(grid)
+        {:ok, pid} = Task.Supervisor.start_link()
+        task = Task.Supervisor.async(pid, fn ->
+          args = ["glider"]
+          Task.start_link(Life.CLI.main(args))
+        end)
+        :timer.sleep(1)
+        Task.shutdown(task)
       end)
   end
+
 end