Fix a bug that tagged logger warning doesn't work with Rails 7

GitHub: fix GH-17

Test::Unit::AssertionFailedError doesn't have the raised exception. We
need to extract the information from message.

Reported by akira yamada. Thanks!!!

lib/test/unit/active_support.rb

@@ -1,4 +1,4 @@
-# Copyright (C) 2012-2022  Sutou Kouhei <[email protected]>
+# Copyright (C) 2012-2024  Sutou Kouhei <[email protected]>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -91,9 +91,12 @@ def mu_pp(object)
       def _assert_nothing_raised_or_warn(assertion, &block)
         assert_nothing_raised(&block)
       rescue Test::Unit::AssertionFailedError => e
-        if tagged_logger && tagged_logger.warn?
+        if tagged_logger &&
+           tagged_logger.warn? &&
+           e.message.start_with?("Exception raised:\n")
+          inspected_exception = e.message.lines[1] || "Unknown exception"
           warning = <<-MSG.gsub(/^\s+/, "")
-            #{self.class} - #{name}: #{e.error.class} raised.
+            #{self.class} - #{name}: #{inspected_exception.strip} raised.
             If you expected this exception, use `assert_raise` as near to the code that raises as possible.
             Other block based assertions (e.g. `#{assertion}`) can be used, as long as `assert_raise` is inside their block.
           MSG

test/test_assertions.rb

@@ -1,4 +1,4 @@
-# Copyright (C) 2015-2022  Kouhei Sutou <[email protected]>
+# Copyright (C) 2015-2024  Sutou Kouhei <[email protected]>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -14,6 +14,8 @@
 # License along with this library; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 
+require "stringio"
+
 class TestAssertions < ActiveSupport::TestCase
   test "assert_not" do
     assert_not(false)
@@ -34,12 +36,26 @@ class TestAssertions < ActiveSupport::TestCase
           raise "Unexpected"
         end
       end
+    elsif ActiveSupport.version < Gem::Version.new("7")
+      assert_raise(Test::Unit::AssertionFailedError) do
+        assert_difference("x", 1) do
+          raise "Unexpected"
+        end
+      end
     else
+      logdev = StringIO.new
+      self.tagged_logger = ActiveSupport::TaggedLogging.new(Logger.new(logdev))
       assert_raise(Test::Unit::AssertionFailedError) do
         assert_difference("x", 1) do
           raise "Unexpected"
         end
       end
+      assert_equal(<<-MESSAGE, logdev.string)
+#{self.class} - #{name}: RuntimeError(<Unexpected>) raised.
+If you expected this exception, use `assert_raise` as near to the code that raises as possible.
+Other block based assertions (e.g. `assert_difference`) can be used, as long as `assert_raise` is inside their block.
+
+      MESSAGE
     end
   end