18 files changed, 346 insertions, 37 deletions
diff --git a/test/-ext-/bug_reporter/test_bug_reporter.rb b/test/-ext-/bug_reporter/test_bug_reporter.rb
index 8293408518..d402ab1382 100644
--- a/test/-ext-/bug_reporter/test_bug_reporter.rb
+++ b/test/-ext-/bug_reporter/test_bug_reporter.rb
@@ -6,8 +6,6 @@ require_relative '../../lib/parser_support'
 
 class TestBugReporter < Test::Unit::TestCase
   def test_bug_reporter_add
-    pend "macOS 15 is not working with this test" if macos?(15)
-
     description = RUBY_DESCRIPTION
     description = description.sub(/\+PRISM /, '') unless ParserSupport.prism_enabled_in_subprocess?
     expected_stderr = [
diff --git a/test/net/http/test_http.rb b/test/net/http/test_http.rb
index c9a27d87cb..366b4cd12c 100644
--- a/test/net/http/test_http.rb
+++ b/test/net/http/test_http.rb
@@ -494,12 +494,10 @@ module TestNetHTTP_version_1_1_methods
 
   def test_s_post
     url = "http://#{config('host')}:#{config('port')}/?q=a"
-    res = assert_warning(/Content-Type did not set/) do
-      Net::HTTP.post(
-              URI.parse(url),
-              "a=x")
-    end
-    assert_equal "application/x-www-form-urlencoded", res["Content-Type"]
+    res = Net::HTTP.post(
+            URI.parse(url),
+            "a=x")
+    assert_equal "application/octet-stream", res["Content-Type"]
     assert_equal "a=x", res.body
     assert_equal url, res["X-request-uri"]
 
@@ -570,9 +568,7 @@ module TestNetHTTP_version_1_1_methods
       th = Thread.new do
         err = !windows? ? Net::WriteTimeout : Net::ReadTimeout
         assert_raise(err) do
-          assert_warning(/Content-Type did not set/) do
-            conn.post('/', "a"*50_000_000)
-          end
+          conn.post('/', "a"*50_000_000)
         end
       end
       assert th.join(EnvUtil.apply_timeout_scale(10))
diff --git a/test/net/http/utils.rb b/test/net/http/utils.rb
index b41341d0a0..067cca02e3 100644
--- a/test/net/http/utils.rb
+++ b/test/net/http/utils.rb
@@ -71,6 +71,11 @@ module TestNetHTTPUtils
         socket.write "HTTP/1.1 100 Continue\r\n\r\n"
       end
 
+      # Set default Content-Type if not provided
+      if !headers['Content-Type'] && (method == 'POST' || method == 'PUT' || method == 'PATCH')
+        headers['Content-Type'] = 'application/octet-stream'
+      end
+
       req = Request.new(method, path, headers, socket)
       if @procs.key?(req.path) || @procs.key?("#{req.path}/")
         proc = @procs[req.path] || @procs["#{req.path}/"]
@@ -306,16 +311,18 @@ module TestNetHTTPUtils
     scheme = headers['X-Request-Scheme'] || 'http'
     host = @config['host']
     port = socket.addr[1]
-    charset = parse_content_type(headers['Content-Type'])[1]
+    content_type = headers['Content-Type'] || 'application/octet-stream'
+    charset = parse_content_type(content_type)[1]
     path = "#{scheme}://#{host}:#{port}#{path}"
     path = path.encode(charset) if charset
-    response = "HTTP/1.1 200 OK\r\nContent-Type: #{headers['Content-Type']}\r\nContent-Length: #{body.bytesize}\r\nX-request-uri: #{path}\r\n\r\n#{body}"
+    response = "HTTP/1.1 200 OK\r\nContent-Type: #{content_type}\r\nContent-Length: #{body.bytesize}\r\nX-request-uri: #{path}\r\n\r\n#{body}"
     socket.print(response)
   end
 
   def handle_patch(path, headers, socket)
     body = socket.read(headers['Content-Length'].to_i)
-    response = "HTTP/1.1 200 OK\r\nContent-Type: #{headers['Content-Type']}\r\nContent-Length: #{body.bytesize}\r\n\r\n#{body}"
+    content_type = headers['Content-Type'] || 'application/octet-stream'
+    response = "HTTP/1.1 200 OK\r\nContent-Type: #{content_type}\r\nContent-Length: #{body.bytesize}\r\n\r\n#{body}"
     socket.print(response)
   end
 
diff --git a/test/prism/fixtures/strings.txt b/test/prism/fixtures/strings.txt
index 0787152786..77e1e4acff 100644
--- a/test/prism/fixtures/strings.txt
+++ b/test/prism/fixtures/strings.txt
@@ -146,6 +146,10 @@ baz
 
 %Q{abc}
 
+%Q(\«)
+
+%q(\«)
+
 %^#$^#
 
 %@#@#
diff --git a/test/ruby/namespace/instance_variables.rb b/test/ruby/namespace/instance_variables.rb
new file mode 100644
index 0000000000..1562ad5d45
--- /dev/null
+++ b/test/ruby/namespace/instance_variables.rb
@@ -0,0 +1,21 @@
+class String
+  class << self
+    attr_reader :str_ivar1
+
+    def str_ivar2
+      @str_ivar2
+    end
+  end
+
+  @str_ivar1 = 111
+  @str_ivar2 = 222
+end
+
+class StringDelegator < BasicObject
+private
+  def method_missing(...)
+    ::String.public_send(...)
+  end
+end
+
+StringDelegatorObj = StringDelegator.new
diff --git a/test/ruby/test_compile_prism.rb b/test/ruby/test_compile_prism.rb
index 819d0d35aa..86f7f0b14f 100644
--- a/test/ruby/test_compile_prism.rb
+++ b/test/ruby/test_compile_prism.rb
@@ -1053,6 +1053,9 @@ module Prism
       assert_prism_eval("for foo, in  [1,2,3] do end")
 
       assert_prism_eval("for i, j in {a: 'b'} do; i; j; end")
+
+      # Test splat node as index in for loop
+      assert_prism_eval("for *x in [[1,2], [3,4]] do; x; end")
     end
 
     ############################################################################
diff --git a/test/ruby/test_data.rb b/test/ruby/test_data.rb
index bb38f8ec91..dd698fdcc4 100644
--- a/test/ruby/test_data.rb
+++ b/test/ruby/test_data.rb
@@ -280,4 +280,10 @@ class TestData < Test::Unit::TestCase
     assert_not_same(test, loaded)
     assert_predicate(loaded, :frozen?)
   end
+
+  def test_frozen_subclass
+    test = Class.new(Data.define(:a)).freeze.new(a: 0)
+    assert_kind_of(Data, test)
+    assert_equal([:a], test.members)
+  end
 end
diff --git a/test/ruby/test_namespace.rb b/test/ruby/test_namespace.rb
index 395f244c8e..f13063be48 100644
--- a/test/ruby/test_namespace.rb
+++ b/test/ruby/test_namespace.rb
@@ -222,6 +222,26 @@ class TestNamespace < Test::Unit::TestCase
     end;
   end
 
+  def test_instance_variable
+    pend unless Namespace.enabled?
+
+    @n.require_relative('namespace/instance_variables')
+
+    assert_equal [], String.instance_variables
+    assert_equal [:@str_ivar1, :@str_ivar2], @n::StringDelegatorObj.instance_variables
+    assert_equal 111, @n::StringDelegatorObj.str_ivar1
+    assert_equal 222, @n::StringDelegatorObj.str_ivar2
+    assert_equal 222, @n::StringDelegatorObj.instance_variable_get(:@str_ivar2)
+
+    @n::StringDelegatorObj.instance_variable_set(:@str_ivar3, 333)
+    assert_equal 333, @n::StringDelegatorObj.instance_variable_get(:@str_ivar3)
+    @n::StringDelegatorObj.remove_instance_variable(:@str_ivar1)
+    assert_nil @n::StringDelegatorObj.str_ivar1
+    assert_equal [:@str_ivar2, :@str_ivar3], @n::StringDelegatorObj.instance_variables
+
+    assert_equal [], String.instance_variables
+  end
+
   def test_methods_added_in_namespace_are_invisible_globally
     pend unless Namespace.enabled?
 
diff --git a/test/ruby/test_object.rb b/test/ruby/test_object.rb
index 7d00422629..9074e54df5 100644
--- a/test/ruby/test_object.rb
+++ b/test/ruby/test_object.rb
@@ -950,6 +950,19 @@ class TestObject < Test::Unit::TestCase
     assert_match(/\bInspect\u{3042}:.* @\u{3044}=42\b/, x.inspect)
     x.instance_variable_set("@\u{3046}".encode(Encoding::EUC_JP), 6)
     assert_match(/@\u{3046}=6\b/, x.inspect)
+
+    x = Object.new
+    x.singleton_class.class_eval do
+      private def instance_variables_to_inspect = [:@host, :@user]
+    end
+
+    x.instance_variable_set(:@host, "localhost")
+    x.instance_variable_set(:@user, "root")
+    x.instance_variable_set(:@password, "hunter2")
+    s = x.inspect
+    assert_include(s, "@host=\"localhost\"")
+    assert_include(s, "@user=\"root\"")
+    assert_not_include(s, "@password=")
   end
 
   def test_singleton_methods
diff --git a/test/ruby/test_ractor.rb b/test/ruby/test_ractor.rb
index b423993df1..e463b504d1 100644
--- a/test/ruby/test_ractor.rb
+++ b/test/ruby/test_ractor.rb
@@ -79,6 +79,26 @@ class TestRactor < Test::Unit::TestCase
     end;
   end
 
+  def test_class_instance_variables
+    assert_ractor(<<~'RUBY')
+      # Once we're in multi-ractor mode, the codepaths
+      # for class instance variables are a bit different.
+      Ractor.new {}.value
+
+      class TestClass
+        @a = 1
+        @b = 2
+        @c = 3
+        @d = 4
+      end
+
+      assert_equal 4, TestClass.remove_instance_variable(:@d)
+      assert_nil TestClass.instance_variable_get(:@d)
+      assert_equal 4, TestClass.instance_variable_set(:@d, 4)
+      assert_equal 4, TestClass.instance_variable_get(:@d)
+    RUBY
+  end
+
   def test_require_raises_and_no_ractor_belonging_issue
     assert_ractor(<<~'RUBY')
       require "tempfile"
@@ -98,6 +118,21 @@ class TestRactor < Test::Unit::TestCase
     RUBY
   end
 
+  def test_require_non_string
+    assert_ractor(<<~'RUBY')
+      require "tempfile"
+      require "pathname"
+      f = Tempfile.new(["file_to_require_from_ractor", ".rb"])
+      f.write("puts 'success'")
+      f.flush
+      result = Ractor.new(f.path) do |path|
+        require Pathname.new(path)
+        "success"
+      end.value
+      assert_equal "success", result
+    RUBY
+  end
+
   def assert_make_shareable(obj)
     refute Ractor.shareable?(obj), "object was already shareable"
     Ractor.make_shareable(obj)
diff --git a/test/ruby/test_rubyoptions.rb b/test/ruby/test_rubyoptions.rb
index 833b6a3b7d..3f79c2afd7 100644
--- a/test/ruby/test_rubyoptions.rb
+++ b/test/ruby/test_rubyoptions.rb
@@ -836,8 +836,6 @@ class TestRubyOptions < Test::Unit::TestCase
   end
 
   def assert_segv(args, message=nil, list: SEGVTest::ExpectedStderrList, **opt, &block)
-    pend "macOS 15 is not working with this assertion" if macos?(15)
-
     # We want YJIT to be enabled in the subprocess if it's enabled for us
     # so that the Ruby description matches.
     env = Hash === args.first ? args.shift : {}
@@ -881,8 +879,6 @@ class TestRubyOptions < Test::Unit::TestCase
   end
 
   def assert_crash_report(path, cmd = nil, &block)
-    pend "macOS 15 is not working with this assertion" if macos?(15)
-
     Dir.mktmpdir("ruby_crash_report") do |dir|
       list = SEGVTest::ExpectedStderrList
       if cmd
diff --git a/test/ruby/test_set.rb b/test/ruby/test_set.rb
index 2bb7858eb2..3a8568762a 100644
--- a/test/ruby/test_set.rb
+++ b/test/ruby/test_set.rb
@@ -130,6 +130,12 @@ class TC_Set < Test::Unit::TestCase
     assert_equal(Set['a','b','c'], set)
 
     set = Set[1,2]
+    ret = set.replace(Set.new('a'..'c'))
+
+    assert_same(set, ret)
+    assert_equal(Set['a','b','c'], set)
+
+    set = Set[1,2]
     assert_raise(ArgumentError) {
       set.replace(3)
     }
diff --git a/test/ruby/test_struct.rb b/test/ruby/test_struct.rb
index ecd8ed196c..db591c306e 100644
--- a/test/ruby/test_struct.rb
+++ b/test/ruby/test_struct.rb
@@ -550,6 +550,12 @@ module TestStruct
     CODE
   end
 
+  def test_frozen_subclass
+    test = Class.new(@Struct.new(:a)).freeze.new(a: 0)
+    assert_kind_of(@Struct, test)
+    assert_equal([:a], test.members)
+  end
+
   class TopStruct < Test::Unit::TestCase
     include TestStruct
 
diff --git a/test/ruby/test_vm_dump.rb b/test/ruby/test_vm_dump.rb
index 709fd5eadf..a3e7b69913 100644
--- a/test/ruby/test_vm_dump.rb
+++ b/test/ruby/test_vm_dump.rb
@@ -5,8 +5,6 @@ return unless /darwin/ =~ RUBY_PLATFORM
 
 class TestVMDump < Test::Unit::TestCase
   def assert_darwin_vm_dump_works(args, timeout=nil)
-    pend "macOS 15 is not working with this assertion" if macos?(15)
-
     assert_in_out_err(args, "", [], /^\[IMPORTANT\]/, timeout: timeout || 300)
   end
 
diff --git a/test/ruby/test_zjit.rb b/test/ruby/test_zjit.rb
index 3b64887f92..6095b0b734 100644
--- a/test/ruby/test_zjit.rb
+++ b/test/ruby/test_zjit.rb
@@ -102,12 +102,39 @@ class TestZJIT < Test::Unit::TestCase
     }, call_threshold: 2
   end
 
+  def test_opt_plus_type_guard_exit_with_locals
+    assert_compiles '[6, 6.0]', %q{
+      def test(a)
+        local = 3
+        1 + a + local
+      end
+      test(1) # profile opt_plus
+      [test(2), test(2.0)]
+    }, call_threshold: 2
+  end
+
   def test_opt_plus_type_guard_nested_exit
-    omit 'rewind_caller_frames is not implemented yet'
-    assert_compiles '[3, 3.0]', %q{
+    assert_compiles '[4, 4.0]', %q{
       def side_exit(n) = 1 + n
       def jit_frame(n) = 1 + side_exit(n)
       def entry(n) = jit_frame(n)
+      entry(2) # profile send
+      [entry(2), entry(2.0)]
+    }, call_threshold: 2
+  end
+
+  def test_opt_plus_type_guard_nested_exit_with_locals
+    assert_compiles '[9, 9.0]', %q{
+      def side_exit(n)
+        local = 2
+        1 + n + local
+      end
+      def jit_frame(n)
+        local = 3
+        1 + side_exit(n) + local
+      end
+      def entry(n) = jit_frame(n)
+      entry(2) # profile send
       [entry(2), entry(2.0)]
     }, call_threshold: 2
   end
@@ -130,7 +157,6 @@ class TestZJIT < Test::Unit::TestCase
   end
 
   def test_opt_mult_overflow
-    omit 'side exits are not implemented yet'
     assert_compiles '[6, -6, 9671406556917033397649408, -9671406556917033397649408, 21267647932558653966460912964485513216]', %q{
       def test(a, b)
         a * b
@@ -205,6 +231,48 @@ class TestZJIT < Test::Unit::TestCase
     }, insns: [:opt_gt], call_threshold: 2
   end
 
+  def test_opt_empty_p
+    assert_compiles('[false, false, true]', <<~RUBY, insns: [:opt_empty_p])
+      def test(x) = x.empty?
+      return test([1]), test("1"), test({})
+    RUBY
+  end
+
+  def test_opt_succ
+    assert_compiles('[0, "B"]', <<~RUBY, insns: [:opt_succ])
+      def test(obj) = obj.succ
+      return test(-1), test("A")
+    RUBY
+  end
+
+  def test_opt_and
+    assert_compiles('[1, [3, 2, 1]]', <<~RUBY, insns: [:opt_and])
+      def test(x, y) = x & y
+      return test(0b1101, 3), test([3, 2, 1, 4], [8, 1, 2, 3])
+    RUBY
+  end
+
+  def test_opt_or
+    assert_compiles('[11, [3, 2, 1]]', <<~RUBY, insns: [:opt_or])
+      def test(x, y) = x | y
+      return test(0b1000, 3), test([3, 2, 1], [1, 2, 3])
+    RUBY
+  end
+
+  def test_opt_not
+    assert_compiles('[true, true, false]', <<~RUBY, insns: [:opt_not])
+      def test(obj) = !obj
+      return test(nil), test(false), test(0)
+    RUBY
+  end
+
+  def test_opt_regexpmatch2
+    assert_compiles('[1, nil]', <<~RUBY, insns: [:opt_regexpmatch2])
+      def test(haystack) = /needle/ =~ haystack
+      return test("kneedle"), test("")
+    RUBY
+  end
+
   def test_opt_ge
     assert_compiles '[false, true, true]', %q{
       def test(a, b) = a >= b
@@ -568,6 +636,22 @@ class TestZJIT < Test::Unit::TestCase
     }
   end
 
+  def test_send_backtrace
+    backtrace = [
+      "-e:2:in 'Object#jit_frame1'",
+      "-e:3:in 'Object#entry'",
+      "-e:5:in 'block in <main>'",
+      "-e:6:in '<main>'",
+    ]
+    assert_compiles backtrace.inspect, %q{
+      def jit_frame2 = caller     # 1
+      def jit_frame1 = jit_frame2 # 2
+      def entry = jit_frame1      # 3
+      entry # profile send        # 4
+      entry                       # 5
+    }, call_threshold: 2
+  end
+
   # tool/ruby_vm/views/*.erb relies on the zjit instructions a) being contiguous and
   # b) being reliably ordered after all the other instructions.
   def test_instruction_order
@@ -589,11 +673,7 @@ class TestZJIT < Test::Unit::TestCase
     pipe_fd = 3
 
     script = <<~RUBY
-      _test_proc = -> {
-        RubyVM::ZJIT.assert_compiles
-        #{test_script}
-      }
-      ret_val = _test_proc.call
+      ret_val = (_test_proc = -> { RubyVM::ZJIT.assert_compiles; #{test_script.lstrip} }).call
       result = {
         ret_val:,
         #{ unless insns.empty?
diff --git a/test/rubygems/test_gem_commands_install_command.rb b/test/rubygems/test_gem_commands_install_command.rb
index 468aecde56..77525aed2c 100644
--- a/test/rubygems/test_gem_commands_install_command.rb
+++ b/test/rubygems/test_gem_commands_install_command.rb
@@ -1005,6 +1005,38 @@ ERROR:  Possible alternatives: non_existent_with_hint
     assert_equal %W[a-3-#{local}], @cmd.installed_specs.map(&:full_name)
   end
 
+  def test_install_gem_platform_specificity_match
+    util_set_arch "arm64-darwin-20"
+
+    spec_fetcher do |fetcher|
+      %w[ruby universal-darwin universal-darwin-20 x64-darwin-20 arm64-darwin-20].each do |platform|
+        fetcher.download "a", 3 do |s|
+          s.platform = platform
+        end
+      end
+    end
+
+    @cmd.install_gem "a", ">= 0"
+
+    assert_equal %w[a-3-arm64-darwin-20], @cmd.installed_specs.map(&:full_name)
+  end
+
+  def test_install_gem_platform_specificity_match_reverse_order
+    util_set_arch "arm64-darwin-20"
+
+    spec_fetcher do |fetcher|
+      %w[ruby universal-darwin universal-darwin-20 x64-darwin-20 arm64-darwin-20].reverse_each do |platform|
+        fetcher.download "a", 3 do |s|
+          s.platform = platform
+        end
+      end
+    end
+
+    @cmd.install_gem "a", ">= 0"
+
+    assert_equal %w[a-3-arm64-darwin-20], @cmd.installed_specs.map(&:full_name)
+  end
+
   def test_install_gem_ignore_dependencies_specific_file
     spec = util_spec "a", 2
 
diff --git a/test/rubygems/test_gem_commands_pristine_command.rb b/test/rubygems/test_gem_commands_pristine_command.rb
index 46c06db014..e9c4d32945 100644
--- a/test/rubygems/test_gem_commands_pristine_command.rb
+++ b/test/rubygems/test_gem_commands_pristine_command.rb
@@ -125,8 +125,8 @@ class TestGemCommandsPristineCommand < Gem::TestCase
       @cmd.execute
     end
 
-    assert File.exist?(gem_bin)
-    assert File.exist?(gem_stub)
+    assert_path_exist gem_bin
+    assert_path_exist gem_stub
 
     out = @ui.output.split "\n"
 
@@ -537,8 +537,8 @@ class TestGemCommandsPristineCommand < Gem::TestCase
       @cmd.execute
     end
 
-    assert File.exist? gem_exec
-    refute File.exist? gem_lib
+    assert_path_exist gem_exec
+    assert_path_not_exist gem_lib
   end
 
   def test_execute_only_plugins
@@ -572,9 +572,9 @@ class TestGemCommandsPristineCommand < Gem::TestCase
       @cmd.execute
     end
 
-    refute File.exist? gem_exec
-    assert File.exist? gem_plugin
-    refute File.exist? gem_lib
+    assert_path_not_exist gem_exec
+    assert_path_exist gem_plugin
+    assert_path_not_exist gem_lib
   end
 
   def test_execute_bindir
@@ -606,8 +606,8 @@ class TestGemCommandsPristineCommand < Gem::TestCase
       @cmd.execute
     end
 
-    refute File.exist? gem_exec
-    assert File.exist? gem_bindir
+    assert_path_not_exist gem_exec
+    assert_path_exist gem_bindir
   end
 
   def test_execute_unknown_gem_at_remote_source
@@ -659,6 +659,42 @@ class TestGemCommandsPristineCommand < Gem::TestCase
     refute_includes "ruby_executable_hooks", File.read(exe)
   end
 
+  def test_execute_default_gem_and_regular_gem
+    a_default = new_default_spec("a", "1.2.0")
+
+    a = util_spec "a" do |s|
+      s.extensions << "ext/a/extconf.rb"
+    end
+
+    ext_path = File.join @tempdir, "ext", "a", "extconf.rb"
+    write_file ext_path do |io|
+      io.write <<-'RUBY'
+      File.open "Makefile", "w" do |f|
+        f.puts "clean:\n\techo cleaned\n"
+        f.puts "all:\n\techo built\n"
+        f.puts "install:\n\techo installed\n"
+      end
+      RUBY
+    end
+
+    install_default_gems a_default
+    install_gem a
+
+    # Remove the extension files for a
+    FileUtils.rm_rf a.gem_build_complete_path
+
+    @cmd.options[:args] = %w[a]
+
+    use_ui @ui do
+      @cmd.execute
+    end
+
+    assert_includes @ui.output, "Restored #{a.full_name}"
+
+    # Check extension files for a were restored
+    assert_path_exist a.gem_build_complete_path
+  end
+
   def test_execute_multi_platform
     a = util_spec "a" do |s|
       s.extensions << "ext/a/extconf.rb"
diff --git a/test/rubygems/test_gem_ext_cargo_builder.rb b/test/rubygems/test_gem_ext_cargo_builder.rb
index 5035937544..b970e442c2 100644
--- a/test/rubygems/test_gem_ext_cargo_builder.rb
+++ b/test/rubygems/test_gem_ext_cargo_builder.rb
@@ -141,6 +141,58 @@ class TestGemExtCargoBuilder < Gem::TestCase
     end
   end
 
+  def test_linker_args
+    orig_cc = RbConfig::MAKEFILE_CONFIG["CC"]
+    RbConfig::MAKEFILE_CONFIG["CC"] = "clang"
+
+    builder = Gem::Ext::CargoBuilder.new
+    args = builder.send(:linker_args)
+
+    assert args[1], "linker=clang"
+    assert_nil args[2]
+  ensure
+    RbConfig::MAKEFILE_CONFIG["CC"] = orig_cc
+  end
+
+  def test_linker_args_with_options
+    orig_cc = RbConfig::MAKEFILE_CONFIG["CC"]
+    RbConfig::MAKEFILE_CONFIG["CC"] = "gcc -Wl,--no-undefined"
+
+    builder = Gem::Ext::CargoBuilder.new
+    args = builder.send(:linker_args)
+
+    assert args[1], "linker=clang"
+    assert args[3], "link-args=-Wl,--no-undefined"
+  ensure
+    RbConfig::MAKEFILE_CONFIG["CC"] = orig_cc
+  end
+
+  def test_linker_args_with_cachetools
+    orig_cc = RbConfig::MAKEFILE_CONFIG["CC"]
+    RbConfig::MAKEFILE_CONFIG["CC"] = "sccache clang"
+
+    builder = Gem::Ext::CargoBuilder.new
+    args = builder.send(:linker_args)
+
+    assert args[1], "linker=clang"
+    assert_nil args[2]
+  ensure
+    RbConfig::MAKEFILE_CONFIG["CC"] = orig_cc
+  end
+
+  def test_linker_args_with_cachetools_and_options
+    orig_cc = RbConfig::MAKEFILE_CONFIG["CC"]
+    RbConfig::MAKEFILE_CONFIG["CC"] = "ccache gcc -Wl,--no-undefined"
+
+    builder = Gem::Ext::CargoBuilder.new
+    args = builder.send(:linker_args)
+
+    assert args[1], "linker=clang"
+    assert args[3], "link-args=-Wl,--no-undefined"
+  ensure
+    RbConfig::MAKEFILE_CONFIG["CC"] = orig_cc
+  end
+
   private
 
   def skip_unsupported_platforms!