Add build_mrbtest after config block is evaluated

This allows us to add `enable_test` anywhere in a build target,
without having to worry about the order in which they are included.

Previously, there was a bug that occured when adding 'mruby-test' gem
to dependencies before additional gems.

Instead of adding the 'mruby-test' gem dependency manually to a test build,
we now only need to call `enable_test` in the target. This also allows us to
call `test_enabled?` downstream when running mruby tests ourselves.

/cc #2924

1 files changed, 1 insertions, 3 deletions

diff --git a/Rakefile b/Rakefile
index 574c1365a..8a8912af5 100644
--- a/Rakefile
+++ b/Rakefile
@@ -116,9 +116,7 @@ end
 desc "run all mruby tests"
 task :test => ["all"] do
   MRuby.each_target do
-    if gems.find { |v| v.name == 'mruby-test' }
-      run_test unless build_mrbtest_lib_only?
-    end
+    run_test if test_enabled?
   end
 end