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ORT is written in Kotlin and uses Gradle as the build system, with Kotlin script instead of Groovy as the DSL. Please ensure to have Gradle's incubating configuration on demand feature disabled as it is currently incompatible with ORT.

When developing on the command line, use the committed Gradle wrapper to bootstrap Gradle in the configured version and execute any given tasks. The most important tasks for this project are:

assembleBuild the JAR artifacts for all projects
detektRun static code analysis on all projects
testRun unit tests for all projects
funTestRun functional tests for all projects
installDistBuild all projects and install the start scripts for distribution

All contributions need to pass the detekt, test and funTest checks before they can be merged.

For IDE development, we recommend the IntelliJ IDEA Community Edition which can directly import the Gradle build files. After cloning the project's source code recursively, run IDEA and use the following steps to import the project.

  1. From the Welcome dialog: Select Open.

    From a running IDEA instance: Select File > New > Project from Existing Sources...

  2. Browse to ORT's source code directory and select either the build.gradle.kts or the settings.gradle.kts file.

  3. In the Open Project dialog select Open as Project.


To set up a basic run configuration for debugging, navigate to OrtMain.kt in the cli module and look for the fun main(args: Array<String>) function. In the gutter next to it, a green "Play" icon should be displayed. Click on it and select Run 'OrtMainKt' to run the entry point, which implicitly creates a run configuration. Double-check that running ORT without any arguments will simply show the command line help in IDEA's Run tool window. Finally, edit the created run configuration to your needs, e.g. by adding an argument and options to run a specific ORT sub-command.


ORT uses Kotest as the test framework. For running tests and individual test cases from the IDE, the Kotest plugin needs to be installed. Afterward, tests can be run via the green "Play" icon from the gutter as described above.

When running functional tests (for package managers) from the command line, ORT supports the special value "unified" for Kotest's kotest.assertions.multi-line-diff system property. When set like

./gradlew -Dkotest.assertions.multi-line-diff=unified -p plugins/package-managers funTest

any failing tests will show the deviation from the expected result in a unified diff format that is compatible with git apply. If the actual result should be taken as the new expected result, copy the diff from the console to the clipboard and run

  • wl-paste | patch -p1 (Linux with Wayland)
  • xsel -b | patch -p1 (Linux with X)
  • cat /dev/clipboard | patch -p1 (Windows with Git Bash)
  • pbpaste | patch -p1 (macOS)

to apply the diff to the local Git working tree (this does not create a commit yet). After reviewing the changes, create a commit to accept the new expected result.

Static Analysis

To ensure consistent code style, ORT uses several static analysis tools. These tools are run as part of the CI pipeline, but it is recommended to run them locally before pushing changes. The most important tools are listed below. For the full list, see the GitHub workflow.


Commitlint is used to ensure that commit messages follow the Conventional Commits specification. It can be executed locally using npx. For example, to check the last two commits, run:

npx commitlint --from=HEAD~2


Detekt is used to run static code analysis on the Kotlin code. It can be executed locally using the Gradle tasks for each source set:

./gradlew detektMain detektTestFixtures detektTest detektFunTest

The above tasks can be slow because they use type resolution. To run only the subset of rules that do not require type resolution, use:

./gradlew detekt


Markdownlint is used to check the Markdown files. Instead of a line-length limit, for Markdown files the "one sentence per line" rule is enforced. This check requires installing a Markdownlint extension:

npm install -g markdownlint-rule-max-one-sentence-per-line@0.0.2

Markdownlint can be executed locally using npx:

npx markdownlint-cli2

Want to Help or have Questions?

All contributions are welcome. If you are interested in contributing, please read our contributing guide. To get quick answers to your questions, join our Slack community or start a GitHub discussion.