From f4f5f0a009f6335ad13b8651bf43a216442c49a7 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Sat, 6 Dec 2025 19:32:14 +0900
Subject: [PATCH] Add error case tests for `File.path`

- for non-String argument
- for NUL-contained argument
- for ASCII-incompatible argument
---
 spec/ruby/core/file/path_spec.rb  | 41 +++++++++++++++++++++++++++++++
 test/ruby/test_file_exhaustive.rb | 21 +++++++++++-----
 2 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/spec/ruby/core/file/path_spec.rb b/spec/ruby/core/file/path_spec.rb
index dfa0c4ec02..726febcc2b 100644
--- a/spec/ruby/core/file/path_spec.rb
+++ b/spec/ruby/core/file/path_spec.rb
@@ -37,4 +37,45 @@ describe "File.path" do
     path.should_receive(:to_path).and_return("abc")
     File.path(path).should == "abc"
   end
+
+  it "raises TypeError when #to_path result is not a string" do
+    path = mock("path")
+    path.should_receive(:to_path).and_return(nil)
+    -> { File.path(path) }.should raise_error TypeError
+
+    path = mock("path")
+    path.should_receive(:to_path).and_return(42)
+    -> { File.path(path) }.should raise_error TypeError
+  end
+
+  it "raises ArgumentError for string argument contains NUL character" do
+    -> { File.path("\0") }.should raise_error ArgumentError
+    -> { File.path("a\0") }.should raise_error ArgumentError
+    -> { File.path("a\0c") }.should raise_error ArgumentError
+  end
+
+  it "raises ArgumentError when #to_path result contains NUL character" do
+    path = mock("path")
+    path.should_receive(:to_path).and_return("\0")
+    -> { File.path(path) }.should raise_error ArgumentError
+
+    path = mock("path")
+    path.should_receive(:to_path).and_return("a\0")
+    -> { File.path(path) }.should raise_error ArgumentError
+
+    path = mock("path")
+    path.should_receive(:to_path).and_return("a\0c")
+    -> { File.path(path) }.should raise_error ArgumentError
+  end
+
+  it "raises Encoding::CompatibilityError for ASCII-incompatible string argument" do
+    path = "abc".encode(Encoding::UTF_32BE)
+    -> { File.path(path) }.should raise_error Encoding::CompatibilityError
+  end
+
+  it "raises Encoding::CompatibilityError when #to_path result is ASCII-incompatible" do
+    path = mock("path")
+    path.should_receive(:to_path).and_return("abc".encode(Encoding::UTF_32BE))
+    -> { File.path(path) }.should raise_error Encoding::CompatibilityError
+  end
 end
diff --git a/test/ruby/test_file_exhaustive.rb b/test/ruby/test_file_exhaustive.rb
index 222578be26..394dc47603 100644
--- a/test/ruby/test_file_exhaustive.rb
+++ b/test/ruby/test_file_exhaustive.rb
@@ -204,12 +204,21 @@ class TestFileExhaustive < Test::Unit::TestCase
     end
 
     conv_error = ->(method, msg = "converting with #{method}") {
-      o = Struct.new(method).new(42)
-      assert_raise(TypeError, msg) {File.path(o)}
-      o = Struct.new(method).new("abc".encode(Encoding::UTF_32BE))
-      assert_raise(Encoding::CompatibilityError, msg) {File.path(o)}
-      o = Struct.new(method).new("\0")
-      assert_raise(ArgumentError, msg) {File.path(o)}
+      test = ->(&new) do
+        o = new.(42)
+        assert_raise(TypeError, msg) {File.path(o)}
+
+        o = new.("abc".encode(Encoding::UTF_32BE))
+        assert_raise(Encoding::CompatibilityError, msg) {File.path(o)}
+
+        ["\0", "a\0", "a\0c"].each do |path|
+          o = new.(path)
+          assert_raise(ArgumentError, msg) {File.path(o)}
+        end
+      end
+
+      test.call(&:itself)
+      test.call(&Struct.new(method).method(:new))
     }
 
     conv_error[:to_path]