this is a really good first commit

test/something_erlang_web/controllers/error_json_test.exs

@@ -0,0 +1,12 @@
+defmodule SomethingErlangWeb.ErrorJSONTest do
+  use SomethingErlangWeb.ConnCase, async: true
+
+  test "renders 404" do
+    assert SomethingErlangWeb.ErrorJSON.render("404.json", %{}) == %{errors: %{detail: "Not Found"}}
+  end
+
+  test "renders 500" do
+    assert SomethingErlangWeb.ErrorJSON.render("500.json", %{}) ==
+             %{errors: %{detail: "Internal Server Error"}}
+  end
+end