tests: predictable and simpler tempfile management

Instead of using completely random names, we'll use
predictable ones since we already depend on them for
exit codes and such.  This drops our ability to run
the same test for the same version of Ruby in the
same working tree, but that's an unlikely scenario.

While we're at it, avoid remove tempfiles if a test
failed.  This should make debugging easier.

1 files changed, 1 insertions, 1 deletions

diff --git a/t/GNUmakefile b/t/GNUmakefile
index 993aa35..552f9d0 100644
--- a/t/GNUmakefile
+++ b/t/GNUmakefile
@@ -14,7 +14,7 @@ ifeq ($(RUBYLIB),)
 else
   RUBYLIB := $(rainbows_lib):$(RUBYLIB)
 endif
-export RUBYLIB
+export RUBYLIB RUBY_VERSION
 
 T = $(wildcard t[0-9][0-9][0-9][0-9]-*.sh)