Require pathname in FormData::File

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- `FormData::File` raised `NameError` on Ruby 3.4 and older when nothing
+  else had loaded Pathname, for example with `--disable-gems`.
+
 ## [3.0.1] - 2026-03-20
 
 ### Changed

lib/http/form_data/file.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "pathname"
+
 module HTTP
   module FormData
     # Represents file form param.

test/http/form_data/file_test.rb

@@ -35,6 +35,15 @@ def each_source
 
   public
 
+  # Pathname is only part of core Ruby from 4.0, and RubyGems usually
+  # loads it, so this checks in a process without RubyGems.
+  def test_loads_without_rubygems
+    lib = File.expand_path("../../../lib", __dir__)
+    code = 'require "stringio"; require "http/form_data"; HTTP::FormData::File.new(StringIO.new("x"))'
+
+    assert system({ "RUBYOPT" => nil }, RbConfig.ruby, "--disable-gems", "-I", lib, "-e", code, err: File::NULL)
+  end
+
   # --- Core Readable behavior across IO sources ---
 
   def test_size