* common.mk: add a comment how to use "make test-all"

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52177 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,7 @@
+Sun Oct 18 13:03:09 2015  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* common.mk: add a comment how to use "make test-all"
+
 Sun Oct 18 12:59:22 2015  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* common.mk: add comments how to use "make benchmark"

common.mk

@@ -590,6 +590,8 @@ no-test-testframework: PHONY
 
 test: test-sample btest-ruby test-knownbug
 
+# $ make test-all TESTOPTS="--help" displays more detail
+# for example, make test-all TESTOPTS="-j2 -v -n test-name -- test-file-name"
 test-all: $(TEST_RUNNABLE)-test-all
 yes-test-all: prog PHONY
 	$(Q)$(exec) $(RUNRUBY) "$(srcdir)/test/runner.rb" --ruby="$(RUNRUBY)" $(TEST_EXCLUDES) $(TESTOPTS) $(TESTS)
@@ -1072,7 +1074,7 @@ help: PHONY
 	"  test-all:        all ruby tests [TESTS=<test files>]" \
 	"  test-rubyspec:   run RubySpec test suite" \
 	"  update-rubyspec: update local copy of RubySpec" \
-	"  benchmark:       benchmark this ruby and COMPARE_RUBY" \
+	"  benchmark:       benchmark this ruby and COMPARE_RUBY." \
 	"  gcbench:         gc benchmark [GCBENCH_ITEM=<item_name>]" \
 	"  gcbench-rdoc:    gc benchmark with GCBENCH_ITEM=rdoc" \
 	"  install:         install all ruby distributions" \