[ruby-cvs:78431] fa0f3eff22 (master): [ruby/fileutils] Fix error printing test failure

David Rodríguez	2019-11-30 22:01:18 +0900 (Sat, 30 Nov 2019)

  New Revision: fa0f3eff22

  https://github.com/ruby/ruby/commit/fa0f3eff22

  Log:
    [ruby/fileutils] Fix error printing test failure
    
    `exception_details` is not defined anywhere.
    
    This commit fixes the following test crash in ruby 2.4
    
    ```
    Error: test_assert_output_lines(TestFileUtils): NoMethodError: undefined method `exception_details' for #<TestFileUtils:0x00005556ef699178>
    ```
    
    And replaces it with an actual test failure:
    
    ```
    [Test::Unit::CoreAssertions::MiniTest::Assertion] exception expected, not #<NoMethodError: undefined method `full_message' for #<RuntimeError: ok>
    Did you mean?  message>.
    ```
    
    https://github.com/ruby/fileutils/commit/2f38ba6e82

  Modified files:
    tool/lib/test/unit/core_assertions.rb