[Housekeeping] Close system port when jobs are cancelled (#182)

* Created a test setup that works

* Refactored test setup into real-world fixes

test/pinchflat/utils/cli_utils_test.exs

@@ -3,6 +3,12 @@ defmodule Pinchflat.Utils.CliUtilsTest do
 
   alias Pinchflat.Utils.CliUtils
 
+  describe "wrap_cmd/3" do
+    test "delegates to System.cmd/3" do
+      assert {"output\n", 0} = CliUtils.wrap_cmd("echo", ["output"])
+    end
+  end
+
   describe "parse_options/1" do
     test "it converts symbol k-v arg keys to kebab case" do
       assert ["--buffer-size", "1024"] = CliUtils.parse_options(buffer_size: 1024)