Don't load *_test.rb file from the "fixtures" folder:

- If an application has files named `*_test.rb` in the
  "fixtures/files" folder, they were picked up to be loaded.
  In most cases this would result in a LoadError as its likely
  those files include code that can't be loaded.

railties/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   `bin/rails test` will no longer load files named `*_test.rb` if they are located in the `fixtures` folder.
+
+    *Edouard Chin*
+
 *   Ensure logger tags configured with `config.log_tags` are still active in `request.action_dispatch` handlers
 
     *KJ Tsanaktsidis*

railties/lib/rails/test_unit/runner.rb

@@ -87,7 +87,7 @@ def default_test_glob
           end
 
           def default_test_exclude_glob
-            ENV["DEFAULT_TEST_EXCLUDE"] || "test/{system,dummy}/**/*_test.rb"
+            ENV["DEFAULT_TEST_EXCLUDE"] || "test/{system,dummy,fixtures}/**/*_test.rb"
           end
 
           def regexp_filter?(arg)

railties/test/application/test_runner_test.rb

@@ -1223,6 +1223,12 @@ class DummyTest < ApplicationSystemTestCase
       assert_match "1 runs, 1 assertions, 0 failures, 0 errors, 0 skips", output
     end
 
+    def test_run_does_not_load_file_from_the_fixture_folder
+      create_test_file "fixtures", "smoke_foo"
+
+      assert_match "0 runs, 0 assertions, 0 failures, 0 errors, 0 skips", run_test_command("")
+    end
+
     def test_can_exclude_files_from_being_tested_via_default_rails_command_by_setting_DEFAULT_TEST_EXCLUDE_env_var
       create_test_file "smoke", "smoke_foo"