.travis.yml: force to execute JIT test on Travis

test_jit.rb: with environment variable RUBY_FORCE_TEST_JIT, we can force
to test JIT availability.

I wanted to have such CI, but Travis was the only option which I can
modify easily.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62327 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

.travis.yml

@@ -61,7 +61,7 @@ before_script:
 
 script:
   - "make -s test TESTOPTS=--color=never"
-  - "make -s $JOBS test-all -o exts TESTOPTS='-q --color=never --job-status=normal'"
+  - "make -s $JOBS test-all -o exts TESTOPTS='-q --color=never --job-status=normal' RUBY_FORCE_TEST_JIT=1"
   - "make -s $JOBS test-spec MSPECOPT=-j"
 
 # Branch matrix.  Not all branches are Travis-ready so we limit branches here.

test/ruby/test_jit.rb

@@ -61,6 +61,12 @@ class TestJIT < Test::Unit::TestCase
   def jit_supported?
     return @jit_supported if defined?(@jit_supported)
 
+    # Experimental. If you want to ensure JIT is working with this test, please set this for now.
+    if ENV.key?('RUBY_FORCE_TEST_JIT')
+      return @jit_supported = true
+    end
+
+    # Very pessimistic check. With this check, we can't ensure JIT is working.
     begin
       _, err = eval_with_jit('proc {}.call', verbose: 1, min_calls: 1, timeout: 10)
       @jit_supported = err.match?(JIT_SUCCESS_PREFIX)