test: avoid minitest stub/mock dependency across Ruby versions

Author: tim-kos

test/test_helper.rb

@@ -13,7 +13,6 @@
 end
 
 require "minitest/autorun"
-require "minitest/mock"
 require "transloadit"
 require "vcr"
 require "open3"
@@ -73,3 +72,29 @@ def run_transloadit_sig(payload, key:, secret:, algorithm: nil)
 end
 
 Minitest::Test.include(TransloaditCliHelpers)
+
+module SingletonMethodOverrideHelpers
+  def with_singleton_method(target, name, implementation)
+    eigenclass = class << target
+      self
+    end
+
+    backup = "__orig_#{name}_for_test__"
+    had_method = eigenclass.method_defined?(name) || eigenclass.private_method_defined?(name)
+    eigenclass.send(:alias_method, backup, name) if had_method
+
+    target.define_singleton_method(name, &implementation)
+    yield
+  ensure
+    eigenclass = class << target
+      self
+    end
+    eigenclass.send(:remove_method, name) rescue nil
+    if had_method
+      eigenclass.send(:alias_method, name, backup)
+      eigenclass.send(:remove_method, backup) rescue nil
+    end
+  end
+end
+
+Minitest::Test.include(SingletonMethodOverrideHelpers)

test/unit/test_transloadit.rb

@@ -109,7 +109,7 @@
 
     it "must produce Transloadit-compatible JSON output" do
       fixed_time = Time.utc(2025, 10, 28, 0, 0, 0)
-      Time.stub :now, fixed_time do
+      with_singleton_method(Time, :now, proc { fixed_time }) do
         _(@transloadit.to_json).must_equal MultiJson.dump(@transloadit.to_hash)
       end
     end

test/unit/transloadit/test_assembly.rb

@@ -146,12 +146,14 @@
       it "must call the create! method with the same parameters" do
         VCR.use_cassette "submit_assembly" do
           file = open("lib/transloadit/version.rb")
-          mocker = Minitest::Mock.new
-          mocker.expect :call, nil, [file]
-          @assembly.stub :create!, mocker do
+          create_arg = nil
+          with_singleton_method(@assembly, :create!, proc { |arg|
+            create_arg = arg
+            nil
+          }) do
             @assembly.submit!(file)
           end
-          mocker.verify
+          _(create_arg).must_equal file
         end
       end
     end