# Detekt — Static Code Analysis for Kotlin

> A static code analysis tool for Kotlin that detects code smells, complexity issues, and style violations with Gradle plugin integration and auto-correction.

## Install

Save in your project root:

# Detekt — Static Code Analysis for Kotlin

## Quick Use
```kotlin
// build.gradle.kts
plugins {
    id("io.gitlab.arturbosch.detekt") version "1.23.7"
}
// Then run:
// ./gradlew detekt
```

## Introduction
Detekt performs static code analysis on Kotlin projects to find code smells, complexity issues, and style violations. It integrates as a Gradle plugin and provides a CLI for standalone use. Its rule set is designed specifically for Kotlin idioms and patterns.

## What Detekt Does
- Analyzes Kotlin source code for complexity, style, naming, and potential bugs
- Provides a Gradle plugin for seamless build integration
- Supports custom rule sets written in Kotlin
- Generates reports in HTML, XML, SARIF, and Markdown formats
- Offers auto-correction for a subset of formatting rules via the detekt-formatting wrapper

## Architecture Overview
Detekt uses the Kotlin compiler embeddable library to parse Kotlin source files into a PSI (Program Structure Interface) tree. Rules are visitors that traverse the PSI tree and report findings. The configuration layer reads a YAML file (`detekt.yml`) that controls which rule sets are active and their threshold parameters. Type resolution is optional and enables deeper analysis when the Kotlin compiler classpath is provided.

## Self-Hosting & Configuration
- Apply the Gradle plugin or download the CLI JAR from GitHub releases
- Generate a default config with `detekt --generate-config` to create `detekt.yml`
- Set complexity thresholds like `maxLineLength`, `maxFunctionLength`, and `maxCyclomaticComplexity`
- Enable type resolution by configuring `classpath` and `jvmTarget` in the Gradle task
- Add the `detekt-formatting` plugin for ktlint-compatible formatting rules

## Key Features
- Kotlin-specific rules that understand coroutines, sealed classes, and data classes
- Complexity metrics including McCabe complexity, lines of code, and nesting depth
- Baseline file support for incremental adoption on existing projects
- SARIF output for GitHub code scanning and IntelliJ IDEA integration
- Parallel analysis for faster execution on multi-module projects

## Comparison with Similar Tools
- **ktlint** — focuses on formatting and style enforcement; Detekt covers broader analysis including complexity and code smells
- **SonarQube** — a full platform with dashboards and history; Detekt is a lightweight CLI and Gradle plugin
- **IntelliJ inspections** — built into the IDE; Detekt runs in CI without an IDE dependency
- **Diktat** — a stricter Kotlin coding convention enforcer; Detekt offers more configurable and flexible rules

## FAQ
**Q: Can Detekt analyze Kotlin Multiplatform projects?**
A: Yes. Configure Detekt for each source set in your Gradle build, and it will analyze common, JVM, JS, and Native source sets.

**Q: How do I suppress a finding for a specific function?**
A: Add `@Suppress("DetektRuleName")` annotation to the function, class, or file.

**Q: Does Detekt support Kotlin script (.kts) files?**
A: Yes. Detekt can analyze `.kt` and `.kts` files including Gradle build scripts.

**Q: How do I create a custom rule?**
A: Implement a class extending `Rule`, override the `visitNamedFunction` or other PSI visitor methods, and package it as a rule set provider in a separate module.

## Sources
- https://github.com/detekt/detekt
- https://detekt.dev/

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Source: https://tokrepo.com/en/workflows/asset-5e849eca
Author: AI Open Source