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Recipe: diff your detekt config with the default one

· One min read

detekt's ./gradlew detektGenerateConfig task copies the default configuration file to the location specified by the config property.

detekt {
  ...
  config = files(...)
  ...
}

When the file on this location already exists, your configuration won't be overwritten, and the task is a noop.

When we release a new version, some users like to generate the default one to compare changed properties. This can be done by running the detekt cli with the --generate-config --config [/new/location] flags. When already using Gradle, we can write a custom task and share this procedure with the team:

import io.gitlab.arturbosch.detekt.DetektGenerateConfigTask

val createDetektConfigForDiff by tasks.registering(DetektGenerateConfigTask::class) {
    description = "Generate newest default detekt config"
    config.setFrom(buildDir.resolve("detekt-diff.yaml"))

    doFirst {
      // optionally delete the old config diff file first 
    }
}

The last step involves calling your favorite diff tool (e.g. diff detekt-diff.yaml my_config.yaml) or using an online service like http://incaseofstairs.com/jsdiff/.

Likewise we can diff the default config of detekt version X with the default config of detekt version X-1. This will tell us which properties are new in version X.