fix(tests): improve semantic correctness of test assertions

- Fix same_keys? test to exercise correct code path
  - Split "list containing non-maps" into two cases:
    - List starting with non-map (exercises fallback clause)
    - List with map followed by non-maps (exercises Enum.all? logic)

- Add nested path key_order test for Objects.encode
  - Verifies path-specific key ordering for nested objects
  - Exercises the Map.fetch(key_order, path) logic

Addresses semantic quality issues found during code review.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Chris Xu

test/toon/encode/objects_test.exs

@@ -102,5 +102,27 @@ defmodule Toon.Encode.ObjectsTest do
 
       assert result == "age: 30\nname: Alice"
     end
+
+    test "uses nested path key_order for nested objects" do
+      opts = %{
+        delimiter: ",",
+        length_marker: nil,
+        indent: 2,
+        indent_string: "  ",
+        key_order: %{["user"] => ["first", "last"]},
+        key_folding: "off"
+      }
+
+      data = %{"user" => %{"last" => "Smith", "first" => "John"}}
+      result = Objects.encode(data, 0, opts) |> IO.iodata_to_binary()
+
+      # Nested "user" object should use specified order: first, last
+      assert result =~ "first: John"
+      assert result =~ "last: Smith"
+      # Verify "first" appears before "last" in the output
+      first_pos = :binary.match(result, "first")
+      last_pos = :binary.match(result, "last")
+      assert elem(first_pos, 0) < elem(last_pos, 0)
+    end
   end
 end

test/toon/utils_test.exs

@@ -44,9 +44,15 @@ defmodule Toon.UtilsTest do
       assert Utils.same_keys?(42) == false
     end
 
-    test "returns false for list containing non-maps" do
+    test "returns false for list starting with non-map" do
+      # Exercises the fallback clause: def same_keys?(_), do: false
       assert Utils.same_keys?([1, 2, 3]) == false
     end
+
+    test "returns false for list with map followed by non-maps" do
+      # Exercises the Enum.all? logic with is_map check inside
+      assert Utils.same_keys?([%{"a" => 1}, 2, 3]) == false
+    end
   end
 
   describe "all_primitives?/1" do