Test Ruby 2.7 on Travis

Generated code does not yet compile, so set as allow_failure for now
rvm master currently needs to be installed when testing ruby-2.7 on Travis

.travis.yml

@@ -300,6 +300,11 @@ matrix:
       env: SWIGLANG=ruby VER=2.6
       sudo: required
       dist: xenial
+    - compiler: gcc
+      os: linux
+      env: SWIGLANG=ruby VER=2.7
+      sudo: required
+      dist: xenial
     - compiler: gcc
       os: linux
       env: SWIGLANG=scilab
@@ -449,6 +454,12 @@ matrix:
       env: SWIGLANG=php VER=7.2
       sudo: required
       dist: xenial
+    # Not yet supported
+    - compiler: gcc
+      os: linux
+      env: SWIGLANG=ruby VER=2.7
+      sudo: required
+      dist: xenial
     # Sometimes hits the Travis 50 minute time limit
     - compiler: clang
       os: osx

Tools/travis-linux-install.sh

@@ -95,6 +95,12 @@ case "$SWIGLANG" in
 		travis_retry sudo apt-get -qq install r-base
 		;;
 	"ruby")
+		if [[ "$VER" == "2.7" ]]; then
+			# Ruby 2.7 support is currently only rvm master (30 Dec 2019)
+			travis_retry rvm get master
+			rvm reload
+			rvm list known
+		fi
 		if [[ "$VER" ]]; then
 			travis_retry rvm install $VER
 		fi