detekt

Meet detekt, a static code analysis tool for the Kotlin programming language. It operates on the abstract syntax tree provided by the Kotlin compiler.

Features

• Code smell analysis for your Kotlin projects
• Complexity reports based on lines of code, cyclomatic complexity and amount of code smells
• Highly configurable rule sets
• Suppression of findings with Kotlin's @Suppress and Java's @SuppressWarnings annotations
• Specification of quality gates which will break your build
• Code Smell baseline and suppression for legacy projects
• Gradle plugin for code analysis via Gradle builds
• SonarQube integration
• Extensibility by enabling incorporation of personal rule sets, FileProcessListener's and OutputReport's
• IntelliJ integration
• Third party integrations for Maven, Bazel and GitHub actions

Project Website

Visit the project website for installation guides, release notes, migration guides, rule descriptions and configuration options.

Quick-Links

• Changelog and migration guides
• Available CLI options
• Rule set and rule descriptions
• Writing custom rules and extending detekt
• Suppressing issues in code
• Suppressing issues via baseline file
• Configuring detekt
• Sample Gradle integrations examples:
  • multi project (Kotlin DSL) with precompiled script plugin
  • single project (Groovy DSL)
  • single project (Unofficial Maven plugin)
  • setup additional detekt task for all modules (Kotlin DSL)
  • setup additional formatting task for all modules (Kotlin DSL)

Quick Start ...

with the command-line interface

curl -sSLO https://github.com/detekt/detekt/releases/download/v[version]/detekt && chmod a+x detekt
./detekt --help

You can find other ways to install detekt here

with Gradle

Gradle 5.4+ is required:

buildscript {
    repositories {
        jcenter()
    }

    // or

    mavenCentral()
    jcenter {
        content {
            // just allow to include kotlinx projects
            // detekt needs 'kotlinx-html' for the html report
            includeGroup "org.jetbrains.kotlinx"
        }
    }
}

plugins {
    id("io.gitlab.arturbosch.detekt").version("[version]")
}

detekt {
    failFast = true // fail build on any finding
    buildUponDefaultConfig = true // preconfigure defaults
    config = files("$projectDir/config/detekt.yml") // point to your custom config defining rules to run, overwriting default behavior
    baseline = file("$projectDir/config/baseline.xml") // a way of suppressing issues before introducing detekt

    reports {
        html.enabled = true // observe findings in your browser with structure and code snippets
        xml.enabled = true // checkstyle like format mainly for integrations like Jenkins
        txt.enabled = true // similar to the console output, contains issue signature to manually edit baseline files
    }
}


// Groovy dsl
tasks.detekt.jvmTarget = "1.8"

// or

// Kotlin dsl
tasks {
    withType<Detekt> {
        // Target version of the generated JVM bytecode. It is used for type resolution.
        this.jvmTarget = "1.8"
    }
}

See maven central for releases and sonatype for snapshots.

Adding more rule sets

detekt itself provides a wrapper over ktlint as a formatting rule set which can be easily added to the Gradle configuration:

dependencies {
    detektPlugins "io.gitlab.arturbosch.detekt:detekt-formatting:[version]"
}

Likewise custom extensions can be added to detekt.

Contributors

If you contributed to detekt but your name is not in the list, please feel free to add yourself to it!

• Artur Bosch - Maintainer
• Marvin Ramin - Collaborator, Bunch of rules, Active on Issues, refactorings, MultiRule
• schalks - Collaborator, Active on Issues, Bunch of rules, Project metrics
• Niklas Baudy - Active on Issues, Bunch of rules, Bug fixes
• lummax - Cli enhancements
• Svyatoslav Chatchenko - Active on Issues, NamingConventions and UnusedImport fixes
• Sean Flanigan - Config from classpath resource
• Sebastian Schuberth - Active on Issues, Windows support
• Olivier Lemasle - NP-Bugfix, rules fixes, Gradle plugin improvement
• Marc Prengemann - Support for custom output formats, prototyped Rule-Context-Issue separation
• Sebastiano Poggi - Build tooling improvements, rules improvements and fixes, docs fixes, Gradle plugin improvements
• Ilya Tretyakov - Sonar runs should not auto correct formatting.
• Andrey T - Readme fix
• Ivan Balaksha - Rules: UnsafeCast, SpreadOperator, UnsafeCallOnNullableType, LabeledExpression
• Anna Y - Readme fix
• Karol Wrótniak - Treat comments as not empty blocks
• Radim Vaculik - VariableMaxLength - bugfix
• Martin Nonnenmacher - UndocumentedPublicClass - enum support
• Dmytro Troynikov - Updated Magic Number rule to ignore Named Arguments
• Andrew Ochsner - Updated Readme for failFast option
• Paul Merlin - Gradle build improvements
• Konstantin Aksenov - Coding improvement
• Matthew Haughton - Added type resolution, Dependency updates, Coding + Documentation improvements
• Janusz Bagiński - Fixed line number reporting for MaxLineLengthRule
• Mike Kobit - Gradle build improvements
• Philipp Hofmann - Readme improvements
• Olivier PEREZ - Fixed Typo in Readme
• Sebastian Kaspari - Html-Output-Format, Documentation fix
• Ilya Zorin - Rule improvement: UnnecessaryAbstractClass
• Gesh Markov - Improve error message for incorrect configuration file
• Patrick Pilch - Rule improvement: ReturnCount
• Serj Lotutovici - Rule improvement: LongParameterList
• Dmitry Primshyts - Rule improvement: MagicNumber
• Egor Neliuba - Rule improvement: EmptyFunctionBlock, EmptyClassBlock
• Said Tahsin Dane - Gradle plugin improvements
• Misa Torres - Added: TrailingWhitespace and NoTabs rules
• R.A. Porter - Updated Readme links to RuleSets
• Robbin Voortman - Rule improvement: MaxLineLength
• Mike Gorunov — Rule improvement: UndocumentedPublicFunction
• Joey Kaan - New rule: MandatoryBracesIfStatements
• Dmitriy Samaryan - Rule fix: SerialVersionUIDInSerializableClass
• Mariano Simone - Rule improvement: UnusedPrivateMember. New Rules: UnusedPrivateClass, VarCouldBeVal
• Shunsuke Maeda - Fix: to work on multi module project using maven plugin
• Mikhail Levchenko - New rules: Unnecessary let, ExplicitItLambdaParameter
• Scott Kennedy - Minor fixes
• Mickele Moriconi - Added: ConstructorParameterNaming and FunctionParameterNaming rules
• Lukasz Jazgar - Fixed configuring formatting rules
• Pavlos-Petros Tournaris - Lazy evaluation of Regex in Rules
• Erhard Pointl - Kotlin DSL and Gradle enhancements
• Tyler Thrailkill - FunctionNaming rule enhancements
• Tarek Belkahia - TooManyFunctions rule options
• Bournane Abdelkrim - Fix typos
• Rafael Toledo - Fix Gradle plugin badge
• Alberto Ballano - ExceptionRaisedInUnexpectedLocation rule improvements
• Guido Pio Mariotti - Documentation improvement
• Mygod - UnusedImports rule improvement
• Andreas Volkmann - yaml code comments
• glammers - Documentation improvement
• Ahmad El-Melegy - yaml syntax fix
• Arjan Kleene - Add unnecessary apply rule
• Paweł Gajda - Rule improvement: FunctionParameterNaming
• Alistair Sykes - Doc improvement
• Andrew Arnott - UnusedPrivateMember improvement
• Tyler Wong - UnderscoresInNumericLiterals rule
• Daniele Conti - ObjectPropertyNaming improvement
• Nicola Corti - Fixed Suppress of MaxLineLenght
• Michael Lotkowski - Rule improvement: False positive UnusedImport for componentN
• Nuno Caro - Adds TXT report support on Gradle plugin
• Minsuk Eom - Rule fix: PackageNaming
• Jonas Alves - Rule fix: MagicNumber with ignoreNamedArgument and a negative value
• Natig Babayev - Readme improvements
• David Phillips - New rule: MandatoryBracesLoops
• Volkan Şahin - Documentation improvement
• Remco Mokveld - Rename Blacklist/Whitelist to more meaningful names
• Zachary Moore - Rule, cli, gradle plugin, and config improvements
• Veyndan Stuart - New rule: UseEmptyCounterpart; Rule improvement: UselessCallOnNotNull
• Parimatch Tech - New rule: LibraryEntitiesShouldNotBePublic
• Chao Zhang - Rule improvement: ImplicitDefaultLocale, ModifierOrder, and LibraryCodeMustReturnSpecifyReturnType
• Marcelo Hernandez - New rule: SuspendFunWithFlowReturnType
• Harold Martin - Rule improvement: ClassOrdering
• Roman Ivanov - Rule improvement: ReturnFromFinally

Mentions

As mentioned in...

• KotlinConf 2018 - Safe(r) Kotlin Code - Static Analysis Tools for Kotlin by Marvin Ramin
• droidcon NYC 2018 - Static Code Analysis For Kotlin
• Kotlin on Code Quality Tools - by @vanniktech Slides Presentation
• @medium/acerezoluna/static-code-analysis-tools-for-kotlin-in-android
• @medium/annayan/writing-custom-lint-rules-for-your-kotlin-project-with-detekt
• Free Continuous Integration for modern Android apps with CircleCI
• Static code analysis for Kotlin in Android
• The Art of Android DevOps
• Android Basics: Continuous Integration
• Kotlin Static Analysis — why and how?
• Check the quality of Kotlin code
• Kotlin Static Analysis Tools
• Speeding up the detekt task in a multi-project Gradle build (for detekt < 1.7.0)
• SBCARS '18 - Are you still smelling it?: A comparative study between Java and Kotlin language by Flauzino et al.
• Preventing software antipatterns with Detekt

Integrations:

• SonarKotlin
• Codacy
• Gradle plugin that generates ErrorProne, Findbugs, Checkstyle, PMD, CPD, Lint, Detekt & Ktlint Tasks for every subproject
• Java library for parsing report files from static code analysis
• sputnik is a free tool for static code review and provides support for detekt
• Novoda Gradle Static Analysis plugin
• Maven plugin that wraps the Detekt CLI
• Bazel plugin that wraps the Detekt CLI
• Gradle plugin that helps facilitate GitHub PR checking and automatic commenting of violations
• Codefactor
• detekt-hint is a plugin to detekt that provides detection of design principle violations through integration with Danger
• GitHub Action: Detekt All

Custom rules from 3rd parties:

• cph-cachet/detekt-verify-implementation
• detekt-hint is a plugin to detekt that provides detection of design principle violations through integration with Danger

Credits

• JetBrains - Creating IntelliJ + Kotlin
• PMD & Checkstyle & ktlint - Ideas for threshold values and style rules