Set up testing configuration for jruby
diff --git a/tests.sh b/tests.sh
index 998f5da..f1242a5 100755
--- a/tests.sh
+++ b/tests.sh
@@ -442,6 +442,11 @@
   cd ruby && bash travis-test.sh ruby-2.7.0 && cd ..
 }
 
+build_jruby() {
+  internal_build_cpp  # For conformance tests.
+  cd ruby && bash travis-test.sh jruby-9.2.11.1 && cd ..
+}
+
 build_javascript() {
   internal_build_cpp
   NODE_VERSION=node-v12.16.3-darwin-x64