How to add Scala compiler plugin only for test sources

user_1517328 0
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Is it possible to add a Scala compiler plugin only when compiling test sources?

When a compiler plugin is added by calling SBT's addCompilerPlugin then a library dependency is added. The relevant methods are:

  /** Transforms `dependency` to be in the auto-compiler plugin configuration. */
  def compilerPlugin(dependency: ModuleID): ModuleID =
    dependency.withConfigurations(Some("plugin->default(compile)"))

  /** Adds `dependency` to `libraryDependencies` in the auto-compiler plugin configuration. */
  def addCompilerPlugin(dependency: ModuleID): Setting[Seq[ModuleID]] =
    libraryDependencies += compilerPlugin(dependency)

The question boils down if there is a withConfigurations that causes the plugin to be on the classpath only when compiling test sources. I tried Some("plugin->default(testCompile)") without success.

sbt scala
1 Answers

To answer my own question: It is possible by setting autoCompilerPlugins to false and adding the necessary -Xplugin=... Scalac option manually in the test configuration. This can be done by using the Classpaths.autoPlugins utility method.

In my case I wanted to activate the SemanticDB compiler plugin during tests only. This can be accomplished by the following SBT settings:

    autoCompilerPlugins := false,
    ivyConfigurations += Configurations.CompilerPlugin,
    scalacOptions in Test ++= Classpaths.autoPlugins(update.value, Seq(), ScalaInstance.isDotty(scalaVersion.value)),
    scalacOptions in Test += "-Yrangepos",
    scalacOptions in Test += "-P:semanticdb:text:on",
user_15173280
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