Obtaining Code Coverage Information While running Functional Test Cases

Frontend Code Coverage

Problem Statement / Requirement:

• We Required to obtain code coverage of Angular JS/React Application with the use of Istanbul, a JavaScript test coverage tool. 
• The code coverage should be calculated when we execute and automate the application using selenium test cases or manual testing.

Proposed solution:

• We can use "nyc" command line utility of istanbul for instrumenting the code so that we can capture the coverage.
• The window.__coverage__  will be object where the coverage data will get stored.
• We can the store the coverage obtained into the json file and run through report command to obtain the proper report of the application.

How the solution works:

Utilities addition

• We need to add the command line utility of istanbul nyc using the command.
• npm install --save-dev nyc
• We can add it globally (system wide) or limited to application.

Changes in the package.json

• We need to configure the package.json as per the requirements.
• Addition of nyc configurations  e.g extension, parser plugins, reporter, exclude & include etc.

Advantages

• nyc supports majority of the framework.
• It gives the detailed code coverage e.g how many branches, statements, and lines got covered.
• It provides you with collection of reports e.g, both text on terminal and html report
• We can obtain the code coverage using istanbul without having to do unit testing i.e it works well with manual testing as well automated test cases.
• It supports mocha, ava etc,which are polular unit testing frameworks. 

Disadvantages

• Instrumention has to be done before application comes up, which is an additonal step(on the fly instrumentation is not supported).
• For ts files with decorators we need to add parser-plugins so as to get the files instrumented.
•      Reference : https://github.com/istanbuljs/nyc/issues/1437
• After the instrumentation of ts files with the decorators it gives comile-time error.
•      Reference : https://github.com/istanbuljs/nyc/issues/1411
• Jsx and Tsx file instrumentation is not happening properly
•      Reference : https://github.com/istanbuljs/nyc/issues/1334

Additional tool tried for React JS

• We have tried cypress CRA for the react JS application and it only works with React JS.

References

• https://istanbul.js.org/
• https://github.com/istanbuljs/nyc/issues/1437
• https://www.npmjs.com/package/@cypress/instrument-cra

Java Code Coverage

Problem Statement

• We Required to obtain code coverage of Java Application with the use of Jacoco code coverage tool
• The code coverage should be calculated when we execute and automate the application using selenium test cases or manual testing.

Proposed solution

• We propose to use the jacoco agent which sits between the application and the request which are coming up to the application with JVM
• We just need to deploy the application with agent

How the solution works

Sample Commands

Java -javaagent:PATH_TO_JACOCO_AGENT_JAR/jacocoagent.jar=destfile=PATH_TO_GENERATE_JACOCO_EXEC_FILE/jacoco.exec,output=file,append=false

java -jar PATH_TO_JACOCO_DIRECTORY/jacococli.jar report jacoco.exec --classfiles PATH_TO_APPLICATION_CLASS_FILES --html PATH_TO_HTML_REPORT_DIRECTORY

References

• https://www.eclemma.org/jacoco/trunk/doc/agent.html#:~:text=The%20JaCoCo%20agent%20collects%20execution,written%20to%20a%20local%20file.
• https://www.jacoco.org/jacoco/trunk/doc/implementation.html
• https://automationbyte.com/integrate-jacoco-agent-on-tomcat-in-these-simple-steps/