- (Re)Fixed marshalling of exceptions, neutering them in 2 passes.

[git-p4: depot-paths = "//src/minitest/dev/": change = 13432]

lib/minitest/test.rb

@@ -203,12 +203,27 @@ def capture_exceptions # :nodoc:
 
     def sanitize_exception e # :nodoc:
       Marshal.dump e
-      e
+      e                                         # good: use as-is
     rescue TypeError
+      neuter_exception e
+    end
+
+    def neuter_exception e
       bt = e.backtrace
-      e = RuntimeError.new "Wrapped undumpable exception for: #{e.class}: #{e.message}"
-      e.set_backtrace bt
-      e
+      msg = e.message.dup
+
+      new_exception e.class, msg, bt            # e.class can be a problem...
+    rescue TypeError
+      msg.prepend "Neutered Exception #{e.class}: "
+
+      new_exception RuntimeError, msg, bt       # but if this raises, we die
+    end
+
+    def new_exception klass, msg, bt
+      ne = klass.new msg
+      ne.set_backtrace bt
+      Marshal.dump ne                           # can raise TypeError
+      ne
     end
 
     def with_info_handler &block # :nodoc:

test/minitest/test_minitest_test.rb

@@ -838,13 +838,52 @@ def test_spec_marshal
   end
 
   def test_spec_marshal_with_exception
-    klass = describe("whatever") { it("passes") { raise Class.new(StandardError)} }
+    klass = describe("whatever") {
+      it("raises, badly") {
+        raise Class.new(StandardError), "this is bad!"
+      }
+    }
+
     rm = klass.runnable_methods.first
 
     # Run the test
     @tc = klass.new(rm).run
 
     assert_kind_of Minitest::Result, @tc
+    assert_instance_of Minitest::UnexpectedError, @tc.failure
+
+    msg = @tc.failure.error.message
+    assert_includes msg, "Neutered Exception #<Class:"
+    assert_includes msg, "this is bad!"
+
+    # Pass it over the wire
+    over_the_wire = Marshal.load Marshal.dump @tc
+
+    assert_equal @tc.time,       over_the_wire.time
+    assert_equal @tc.name,       over_the_wire.name
+    assert_equal @tc.assertions, over_the_wire.assertions
+    assert_equal @tc.failures,   over_the_wire.failures
+    assert_equal @tc.klass,      over_the_wire.klass
+  end
+
+  def test_spec_marshal_with_exception_nameerror
+    klass = describe("whatever") {
+      it("raises nameerror") {
+        NOPE::does_not_exist
+      }
+    }
+
+    rm = klass.runnable_methods.first
+
+    # Run the test
+    @tc = klass.new(rm).run
+
+    assert_kind_of Minitest::Result, @tc
+    assert_instance_of Minitest::UnexpectedError, @tc.failure
+
+    msg = @tc.failure.error.message
+    assert_includes msg, "uninitialized constant TestMinitestRunnable::NOPE"
+    assert_includes msg, "NOPE::does_not_exist"
 
     # Pass it over the wire
     over_the_wire = Marshal.load Marshal.dump @tc