Add more tests

lib/tmp.ex

@@ -103,10 +103,12 @@ defmodule Tmp do
     Tmp.Worker.execute(monitor, path, function, timeout)
   end
 
-  defp dirname(_prefix = nil), do: rand_dirname()
-  defp dirname(prefix), do: prefix <> "-" <> rand_dirname()
+  @doc false
+  def dirname(_prefix = nil), do: rand_dirname()
+  def dirname(prefix), do: prefix <> "-" <> rand_dirname()
 
-  defp rand_dirname do
+  @doc false
+  def rand_dirname do
     sec = :os.system_time(:second) |> Integer.to_string()
     rand = :crypto.strong_rand_bytes(5) |> Base.encode16(case: :lower)
 

test/tmp_test.exs

@@ -190,4 +190,19 @@ defmodule TmpTest do
       prefix: "test_custom_base_dir_module"
     )
   end
+
+  test "dirname generates correct format with nil prefix" do
+    dirname = Tmp.dirname(nil)
+    assert String.match?(dirname, ~r/^\d+-[a-f0-9]{10}$/)
+  end
+
+  test "dirname generates correct format with non-nil prefix" do
+    dirname = Tmp.dirname("test")
+    assert String.match?(dirname, ~r/^test-\d+-[a-f0-9]{10}$/)
+  end
+
+  test "rand_dirname generates unique names" do
+    names = for _ <- 1..100, do: Tmp.rand_dirname()
+    assert length(Enum.uniq(names)) == 100
+  end
 end