reapply r46568 "assertions.rb: refine message"

`exception` is an expected exception class, not the raised instance,
so the result message cannot have any backtraces.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46588 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 1 deletions

diff --git a/test/lib/test/unit/assertions.rb b/test/lib/test/unit/assertions.rb
index 869baf505f..435719a22e 100644
--- a/test/lib/test/unit/assertions.rb
+++ b/test/lib/test/unit/assertions.rb
@@ -126,7 +126,7 @@ module Test
           raise TypeError, "Expected #{expected.inspect} to be a kind of String or Regexp, not #{expected.class}"
         end
 
-        ex = assert_raise(exception, *msg) {yield}
+        ex = assert_raise(exception, msg || proc {"Exception(#{exception}) with message matches to #{expected.inspect}"}) {yield}
         msg = message(msg, "") {"Expected Exception(#{exception}) was raised, but the message doesn't match"}
 
         if assert == :assert_equal