1. Introduction
detekt is a powerful static code analysis tool specifically designed for Kotlin projects. In this article, we will explore how to integrate detekt into our Kotlin project, run it using Gradle or through the command line, and leverage its capabilities to improve code quality and maintainability.
Additionally, we’ll discuss the benefits of combining detekt with ktlint for comprehensive code analysis and enforcing coding standards. By incorporating detekt into our development workflow, we can identify potential issues early, write cleaner code, and build robust Kotlin applications.
2. Adding detekt to Our Project
Let’s start by adding detekt to our Kotlin project. We can easily integrate detekt by including the detekt Gradle plugin in our build configuration:
plugins {
id("io.gitlab.arturbosch.detekt") version "1.23.0"
}
By applying this plugin, detekt can be invoked during the build process, enabling us to analyze our code for potential issues.The detekt task is automatically included as part of the check step.
3. Running detekt Using Gradle
Once we’ve added the detekt plugin, running detekt on our codebase becomes effortless. There are multiple ways to execute detekt, depending on our preferences and project setup. The main way of running detekt is by executing its Gradle task:
./gradlew detekt
3.1. Running detekt Gradle Using a GitHub Action
If our project is hosted on GitHub, we can leverage GitHub Actions to automatically run detekt on every push or pull request. Here’s an example configuration for a detekt workflow using Gradle:
name: detekt
on:
push:
jobs:
detekt:
runs-on: ubuntu-latest
steps:
- name: Checkout code
uses: actions/checkout@v3
- name: Run detekt
uses: gradle/gradle-build-action@v2
with:
arguments: detekt
This GitHub Action configuration ensures that detekt is executed whenever changes are pushed to our repository, helping us maintain code quality consistently.
4. Running detekt Outside of Gradle
detekt also provides a command-line tool. This allows us to run it without installing the plugin in our project, which may be easier for some use cases.
4.1. Running detekt on a Codebase Using the Command Line
If we prefer running detekt directly from the command line, we can utilize the detekt executable itself. To execute detekt on our codebase:
- First, let’s make sure we have the detekt CLI (Command Line Interface) installed. We can download the detekt CLI with the instructions from the official detekt Documentation.
- Next, let’s open our command-line interface and navigate to the root directory of our Kotlin project.
- Now, we can run the detekt-cli command to analyze the codebase.
$ detekt-cli
kotlin-tutorials/kotlin-libraries/src/main/kotlin/com/baeldung/kovert/NoopServer.kt:44:45:
This empty block of code can be removed. [EmptyFunctionBlock]
kotlin-tutorials/kotlin-libraries/src/test/kotlin/com/baeldung/kotlin/arrow/FunctionalDataTypesUnitTest.kt:71:18:
The caught exception is swallowed. The original exception could be lost. [SwallowedException]
kotlin-tutorials/kotlin-libraries/src/main/kotlin/com/baeldung/kovert/SimpleServer.kt:34:28:
Function names should match the pattern: [a-z][a-zA-Z0-9]* [FunctionNaming]
...
This command triggers detekt’s analysis of our entire codebase, allowing us to identify potential issues and receive valuable suggestions for improvement.
The detekt executable provides us with a convenient way to run detekt independently of our build tool. It gives us the flexibility to incorporate detekt into our custom scripts or development workflow seamlessly.
4.2. Running detekt CLI Using a GitHub Action
If we want to set up and run the detekt executable in our project, there’s a GitHub Action for that:
name: Install detekt
on:
push:
jobs:
detekt:
runs-on: ubuntu-latest
steps:
- name: Setup detekt
uses: peter-murray/setup-detekt@v2
with:
detekt_version: 1.20
- name: Run detekt
run: detekt-cli --version
This GitHub action will set up the detekt-cli and then execute the customizable detekt-cli command.
5. How to Configure detekt
detekt provides a set of default rules that cover various aspects of code analysis. However, we can further refine the analysis by enabling or disabling specific rules according to our project requirements.
To configure detekt rules, we can create a detekt.yml file in the root directory of our project. In this YAML configuration file, we can specify which rules should be enabled or disabled, tweak their severity levels, and set up rule-specific configurations.
Here’s an example detekt.yml configuration file:
formatting:
Indentation:
active: true
autoCorrect: true
indentSize: 2
NoWildcardImports:
active: true
style:
MagicNumber:
active: false
In this example, we have changed a few detekt settings:
- Activated the Indentation rule
- Changed our indentation size to 2 instead of 4
- Allowed detekt to autocorrect indentation differences
- Activated the NoWildcardImports rule
- Activated the MagicNumber rule
By customizing the detekt rules configuration, we can focus on the specific aspects of code analysis that are relevant to our project and coding standards. We can explore the detekt documentation and experiment with different configuration options to fine-tune detekt to match our project’s requirements and coding style.
Reviewing and updating our detekt configuration periodically as our project evolves or when new code analysis needs arise is important. This ensures that detekt continues to provide relevant and effective analysis for our Kotlin codebase.
6. Additional Rules with ktlint
While detekt provides a comprehensive set of rules and checks for code analysis, combining it with ktlint can further enhance our code quality process. ktlint is a popular linting tool for Kotlin projects, focusing specifically on code style and formatting.
Detekt provides built-in support for integrating ktlint directly into its analysis process. This integration allows us to leverage both detekt’s powerful static code analysis capabilities and ktlint’s code style enforcement within a single tool.
To enable detekt’s integration with ktlint, we can add the detekt-formatting module as a dependency in our build configuration:
dependencies {
detektPlugins("io.gitlab.arturbosch.detekt:detekt-formatting:<detekt-version>")
}
By including the detekt-formatting module, detekt will automatically apply the ktlint rules alongside its own analysis rules during the code analysis process.
When running detekt, it will not only detect potential issues but also provide warnings for any code style violations according to the ktlint rules. This ensures that our codebase adheres to both static analysis and code style standards.
7. Conclusion
detekt is a powerful static code analysis tool that enhances the quality and maintainability of Kotlin projects. By integrating detekt into our development workflow, we can identify potential issues early and enforce coding standards consistently.
The combination of detekt with ktlint allows us to improve both code quality and style. With detekt’s configurable options, we can tailor the analysis to our project’s specific needs.
By utilizing detekt, we can write cleaner, more efficient code and ensure long-term project success. As always, the example code is available over on GitHub.