chore: extraction and centralization of utility functions

test/bds/map_utils_test.exs

@@ -0,0 +1,31 @@
+defmodule BDS.MapUtilsTest do
+  use ExUnit.Case, async: true
+
+  alias BDS.MapUtils
+
+  describe "attr/2" do
+    test "reads atom and string keys while preserving explicit nil" do
+      assert MapUtils.attr(%{title: "Atom title"}, :title) == "Atom title"
+      assert MapUtils.attr(%{"title" => "String title"}, :title) == "String title"
+      assert MapUtils.attr(%{"title" => "fallback", title: nil}, :title) == nil
+      assert MapUtils.attr(%{}, :title) == nil
+    end
+  end
+
+  describe "maybe_put/3" do
+    test "skips nil values and keeps other values" do
+      assert MapUtils.maybe_put(%{}, :title, nil) == %{}
+      assert MapUtils.maybe_put(%{}, :title, "") == %{title: ""}
+      assert MapUtils.maybe_put(%{}, :published, false) == %{published: false}
+    end
+  end
+
+  describe "blank_to_nil/1" do
+    test "normalizes nil and empty string only" do
+      assert MapUtils.blank_to_nil(nil) == nil
+      assert MapUtils.blank_to_nil("") == nil
+      assert MapUtils.blank_to_nil(" ") == " "
+      assert MapUtils.blank_to_nil(42) == 42
+    end
+  end
+end