How to get js code coverage for tomcat application?

[gajananrmahajan]

@tntim96, I can see that you've been handling this project alone. Thanks for all your efforts and keep moving this project!

I'm very new to code coverage and applications deployed in tomcat. Searched a lot and also went through JSCOver doc but could comprehend fully, hence need your help. My questions could be silly but please help me.

My requirement is to get JS Code Coverage of application which is deployed in Tomcat. To hit the code, I'll execute Selenium tests.

In document I can see following command where doc/example has js code(& index.html) which is going to be checked for coverage -

java -jar target/dist/JSCover-all.jar -ws --document-root=doc/example --report-dir=target

In Tomcat, my app is at - /home/oracle/apache-tomcat-8.5.11/webapps/MyApp which is using port 8080. And I hit command -

java -jar target/dist/JSCover-all.jar -ws --document-root=/home/oracle/apache-tomcat-8.5.11/webapps/MyApp --report-dir=target

But it results into error -

Exception in thread "main" java.lang.RuntimeException: java.net.BindException: Address already in use (Bind failed)

1. How can I use different port for server started by above js cover?
2. Am I doing above things correctly? This question is because our team has documented like following and neither is helping me move further

Steps by team -

1. Stop the application i.e MyApp
2. Instrument js files of MyApp with -

java -jar target\dist\JSCover-all.jar -fs --local-storage /home/oracle/apache-tomcat-8.5.11/webapps/MyApp target/MyApp-Ins

This created instrumented folder MyApp-Ins

3. Rename WEB-INF folder from /home/oracle/apache-tomcat-8.5.11/webapps/MyApp to something like WEB-INF-OLD
4. Copied instrumented folder MyApp-Ins under webapps at same level as of MyApp
5. Restart server and access instrumented app like - http://localhost:8080/MyApp-Ins
6. Start JSCover server with -
   java -cp target\dist\JSCover-all.jar jscover.server.SimpleWebServer target/MyApp-Ins 8080

But this results into error -

Exception in thread "main" java.lang.NullPointerException
        at jscover.server.SimpleWebServer.main(SimpleWebServer.java:362)

I did not understand why this failed and why to use port 8080 again here(which is used for app deployed) and use target/MyaApp-Ins which is instrumented in JSCover directory

Please help me how I can proceed with this?

[tntim96]

If the application is deployed, you should instrument the JS code using file-mode before deploying. There is a working example here: https://github.com/tntim96/JSCover/tree/master/examples/localStorage-file-system

There are also other tools that might be better suited for your scenario:
https://blog.logrocket.com/using-the-chrome-devtools-new-code-coverage-feature-ca96c3dddcaf/
https://egghead.io/lessons/javascript-how-to-write-a-javascript-library-adding-code-coverage-recording-with-istanbul