Code Coverage for Kotlin

As you release an app, you don’t want to leave any bugs. This would damage your reputation as a developer. Unfortunately, not all open source code coverage tools are user friendly. Many of these don’t support different coverage levels. Worse, some don’t provide you with support or backup for bugs.

To ease your code coverage testing, we present RKTracer Tool, a handy code coverage tool for any Kotlin programmer.

Table of Contents

What is Kotlin Code and Test Coverage?

Code coverage in Kotlin is a measure of code executed during testing. 

On the other hand, kotlin test coverage is a measure of the extent to which the feature being tested has been covered by tests. 

Code coverage tells you about all areas of the app that aren’t covered in any tests. It prompts you to investigate all untested areas. 

The percentages don’t necessarily matter, but the information regarding code that’s not being executed is useful for your project’s success. 

Test coverage percentages will only relate to your known test ideas. For instance, you might think that running 20 tests will give you a 100% test coverage. However, there are more tests that you couldn’t have thought of that would give you a different result.

Kotlin language and its Build Environment 

A free, open-source programming language, Kotlin targets JavaScript, JVBM, Native, and Android. This language was launched by JetBrains and was first released in February 2016.  An updated version 1.4.10  was later published on September 10, 2020.  

You can use it in both FP and OO styles. You can also mix the two elements while doing functional programming. 

Kotlin boasts of being more concise. To back this up, estimates indicate that about 40% of code lines are cut using this language. It supports non-nullable types and makes applications less prone to NPEs. 

You can write expressive code and create DSL. This is enabled by Kotlin’s smart casting, lambdas, extension functions, and higher-order functions. 

More to this, Kotlin is fully interoperable with Java. There’s even an automated IDE Java-to-Kotlin converter that makes it easy for you to migrate existing code.

Klotin and Android Studio Relationship

You can evaluate the logic of your Android App and use RKTracer for code coverage generation. Check the Kotlin Code Coverage Demo Video.  How to instrument app in Android Studio, Test in the emulator, and generate code coverage. To do this, you do not have to run every single unit on a real device. 

With this, you’ll find yourself fulfilling your dependency relationships faster. This applies to both complex and minimal interactions within the app’s framework. 

You’ll have to store your source files for local unit tests in your Android Studio directory. 

With RKTracer, you’ll find it easy configuring the testing dependencies to simplify local unit tests. 

Types of Kotlin Tests and JUnit framework 

WIth RKTracer, you may use unit testing using the JUnit framework. 

JUnit is quite interoperable with Java, and hence, works well-writing tests for Kotlin code. This can be good for you, especially if you have worked with Java and JUnit in the past.  

This, and other Kotlin testing Libraries, use similar assertions as any Java Library. This gives you a chance to test anything from true or false to whether a set has certain elements. 

Other test libraries include: 

  • Kotlin Test: This is the standard framework for Kotlin testing. It provides annotations and assertions and is quite similar to how JUnit works. 
  • MockK: This library enables you to create mocks easily. You can as well mock out the final classes.
  • Mockito 2: Similar to MockK, Mockito 2 enables you to mock the final classes. Kotlin mocking classes and objects work like they do in Java. 

About the RKTracer Code Coverage Tool

To help you understand how to use RKTracer, we have a prime example in our demo

RKTracer supports 0.1.x to the latest android studio versions. It comes with a plugin for Android Studio. The plugin is straightforward to turn on and off. 

The tool supports 1.2.x to the latest Kotlin Versions  in:

  • Windows OS
  • Linux
  • Android

The built environments supported by RKTracer include: 

  • Grandle
  • Maven
  • ANT
  • Support all build environments.

Code coverage levels support: 

  • Line coverage
  • Statement coverage
  • Function Coverage
  • Branch coverage
  • Condition coverage
  • Multiple condition coverage. 
code-coverage-Kotlin

The Working Principle and Benefits of RKTracer

Once your project is ready for testing, RKTracer makes the process easy with a 4-step command. These steps are:

  • Instrumentation using the RKTracer tool.
  • Testing the application.
  • Dump coverage data.
  • Html Report Generation.
RKTracer-working-principle

RKTracer parallels most of its functionality, including fast plug-and-run for project tests. 

It also implements standard unit testing concepts for it to build for a reliable and straightforward testing mechanism. 

RKTracer is meant for an extensive Kotlin android code coverage Gradle. It also allows you to export test results in any popular format that you may like. 

RKTracer can also work together with your build environment to give custom testing solutions and mechanisms. 

Kotlin Unit and Integration Testing 

RKTracer’s unit testing is executed in a few steps. These are:

  • Checking your code out in the respiratory
  • Carrying out required changes
  • Execution of unit tests
  • Fixing defect unit tests
  • Doing a code review
  • Checking the code in the respiratory 

In different operating levels, unit testing will come just before integration testing. The code quality in unit testing identifies its defects. These defects might be aroused before the code is sent for further testing. 

RKTracer has been designed to do integration testing. This ensures that modules interact with third-party tools and APIs. With this, you’ll have good functionality since errors are detected at a good time. 

The tool also supports generating code coverage for testing apps in devices. This will help you generate code coverage without unit test cases. 

How to Generate and Increase Code Coverage Kotlin Using RKTracer tool 

  • Turn your Kotlin project on to have the source files implemented.
  • rktracer -on . kt -v
  • Go ahead and build your project to have your code coverage generated.
  • Run the application and enter the input value. In our example, we run the value 5
kotlin-testing-2
  • Generate the report adding (rkresults) and open it in the browser
code-coverage-kotlin
  • To see a specific file, click on “File Path,” and it will take you there. By this, you will find it easy to find unreachable code even after thorough testing with the help of color coding in the HTML reports generated. 
code-coverage-Kotlin-file

Line, Statement, and Multiple Code Coverage 

Line Coverage, statement coverage, and multiple condition code coverage generated by RKTracer will help you better understand your code. 

  • RKTracer’s Line coverage results will tell you whether each line of your source code is executed at least once upon the test run.
  • Statement coverage results will ensure that each statement in your code is executed at least once
  • With Multiple condition code coverage, you’ll see whether all possible combinations of outcomes are tested at least once
  • Let’s re-run the program with more numbers to test and Again generate the report using the “rkresults” command.

Testing Your Application

RKTracer gives you a chance to test and write test cases manually in your application. You can then uncover code that’s been reported in Code Coverage HTML reports. This helps you ensure that you have tested code with unit testing and ensure that all possible scenarios and logic have been covered.

Even if you have code lines that can’t fit in one screen, you right-click within the given function. This will get you a function summary, a file summary, and the project summary.

With this, you can find the correct input values that you need to parse and uncover the unreachable code. In turn, you can increase your code coverage. It takes a second or less to instrument all the files.

What’s better?

With RKTracer’s backup, you can generate a report as many times and access your old reports at any given moment. It helps you generate code coverage the easy way, with or without test cases.

Our example below ascertained that over 90% of the code had been covered in testing. 

More Benefits of RKTracer 

  • RKTracer plug-in for Android Studio. With just one click, you enable and disable a tool.
  • RKTracer will help you to increase code coverage.
  • You will have an easy time when merging reports from two different tests. You can also combine both of the reports.
  • RKTracer has a continuous integration that’s been automated. You can test Jenkins 18 and check reports.
  • Want to go the sonarqube code coverage way? RKTracer will give you an easy time with Sonarqube kotlin coverage reports. 
  • The tool will give code coverage for tests executed with manual or automation tools if your source code has an if…else loop, the test would still cover both cases.
  • You will have an easy time integrating with testing tools. This will allow you to run automated tests, unit tests, and CI or CD systems.
  • RKTracer collects code coverage at runtime analysis data.
  • RKTracer supports Python, Go, and Swift.

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Code testing will improve the quality and predictability of your software/app. With code coverage, you’re able to:

  • Identify problems in your code at the early stages of your project.
  • Create more tests to maximize coverage.
  • Know the areas of your program that need some work.
  • Measure the quality of your app. 

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