Merge pull request #13392 from rabbitmq/mergify/bp/v4.1.x/pr-13389

Configure location of mocha-test dockerfile (backport #13389)

Author: michaelklishin

selenium/README.md

@@ -209,3 +209,10 @@ following command:
 ```
   npm install
 ```
+
+## Build mocha-test image using a different Dockefile
+
+```bash 
+MOCHA_DOCKER_FILE=\location\of\my\Dockerfile ./run-suites.sh
+```
+

selenium/bin/suite_template

@@ -128,11 +128,15 @@ init_suite() {
 }
 
 build_mocha_image() {
-  begin "Ensuring mocha-test image ..."
+  DOCKER_BUILD_ARGS=""
+  if [[ -n "$MOCHA_DOCKER_FILE" ]]; then 
+    DOCKER_BUILD_ARGS="-f $MOCHA_DOCKER_FILE "
+  fi
+  begin "Ensuring mocha-test image ($DOCKER_BUILD_ARGS) ..."
   tag=($(md5sum $SELENIUM_ROOT_FOLDER/package.json))
   print "> tag : $tag"
   if [[ $(docker images -q mocha-test:$tag 2> /dev/null) == "" ]]; then
-    docker build -t mocha-test:$tag  --target test $SELENIUM_ROOT_FOLDER
+    docker build $DOCKER_BUILD_ARGS -t mocha-test:$tag  --target test $SELENIUM_ROOT_FOLDER
     print "> Built docker image mocha-test:$tag"
   fi
   end "mocha-test image exists"