MiMa Mill Plugin

Port of the MiMa Sbt Plugin

Getting Started

After importing it in the build.sc file:

import $ivy.`com.github.lolgab::mill-mima::x.y.z`
import com.github.lolgab.mill.mima._

this plugin can be mixed in a ScalaModule with PublishModule defining the mimaPreviousVersions:

object module extends ScalaModule with PublishModule with Mima {
  def mimaPreviousVersions = Seq("1.0.0", "1.5.0")

  // ... other settings
}

Configuration

mimaCheckDirection

The required direction of binary compatibility can be set in two ways:

• By setting the MIMA_CHECK_DIRECTION environment variable when running Mill

  MIMA_CHECK_DIRECTION=forward mill __.mimaReportBinaryIssues
  

  The possible values are backward (default), forward and both.

  This is useful when you want to check for different directions at the same time, for example when you might want to have separate CI checks for forward and backward compatibility to evaluate if changes introduce source compatibilities.

• By overriding mimaCheckDirection:

  override def mimaCheckDirection = CheckDirection.Both

  The possible values are CheckDirection.Backward (default), CheckDirection/Forward and CheckDirection.Both.

  This is useful when the setting is static and you want to keep the setting in your build.sc file.

mimaBinaryIssueFilters

When MiMa reports a binary incompatibility that you consider acceptable, such as a change in an internal package, you need to use the mimaBinaryIssueFilters setting to filter it out and get mimaReportBinaryIssues to pass, like so:

import com.github.lolgab.mill.mima._

object mylibrary extends ScalaModule with PublishModule with Mima {
  override def mimaBinaryIssueFilters = super.mimaBinaryIssueFilters() ++ Seq(
    ProblemFilter.exclude[MissingClassProblem]("com.example.mylibrary.internal.Foo")
  )

  // ... other settings
}

You may also use wildcards in the package and/or the top Problem parent type for such situations:

import com.github.lolgab.mill.mima._

override def mimaBinaryIssueFilters = super.mimaBinaryIssueFilters() ++ Seq(
  ProblemFilter.exclude[MissingClassProblem]("com.example.mylibrary.internal.*")
)

mimaExcludeAnnotations

The fully-qualified class names of annotations that exclude parts of the API from problem checking.

import com.github.lolgab.mill.mima._

object mylibrary extends ScalaModule with PublishModule with Mima {
  override def mimaExcludeAnnotations = Seq(
    Seq("mima.annotation.exclude")
  )
  // ... other settings
}

mimaPreviousArtifacts

If your previous artifacts have a different groupId or artifactId you can check against them using mimaPreviousArtifacts instead of millPreviousVersions (since millPreviousVersions assumes the same groupId and artifactId):

def mimaPreviousArtifacts = Agg(
  ivy"my_group_id::module:my_previous_version"
)

mimaCurrentArtifact

The PathRef to the actual artifact that is being checked for binary compatibility. Defaults to use the result of the jar target.

Up until version 0.0.24, this was implemented as compile().classes, for compatibility to the sbt plugin.

def mimaCurrentArtifact = T {
  compile().classes
}

mimaBackwardIssueFilters

Filters to apply to binary issues found grouped by version of a module checked against. These filters only apply to backward compatibility checking.

Signature:

def mimaBackwardIssueFilters: Target[Map[String, Seq[ProblemFilter]]]

mimaForwardIssueFilters

Filters to apply to binary issues found grouped by version of a module checked against. These filters only apply to forward compatibility checking.

Signature:

def mimaForwardIssueFilters: Target[Map[String, Seq[ProblemFilter]]]

IncompatibleSignatureProblem

Most MiMa checks (DirectMissingMethod,IncompatibleResultType, IncompatibleMethType, etc) are against the "method descriptor", which is the "raw" type signature, without any information about generic parameters.

The IncompatibleSignature check compares the Signature, which includes the full signature including generic parameters. This can catch real incompatibilities, but also sometimes triggers for a change in generics that would not in fact cause problems at run time. Notably, it will warn when updating your project to scala 2.12.9+ or 2.13.1+, see this issue for details.

You can opt-in to this check by setting:

def mimaReportSignatureProblems = true

Changelog

0.0.24

• Update MiMa to 1.1.3

0.0.23

• Support Mill 0.11.0

0.0.22

• Support Mill 0.11.0-M11

0.0.21

• Support Mill 0.11.0-M10

0.0.20

• Support Mill 0.11.0-M9

0.0.19

• Support Mill 0.11.0-M8

0.0.18

• Add support for MIMA_CHECK_DIRECTION environment variable

0.0.17

• Update MiMa to 1.1.2
• Support Mill 0.11.0-M7

0.0.13

• Update MiMa to 1.1.1

0.0.12

• Add ReadWriters for CheckDirection

0.0.10

• Run Mima in a separate classloader. Now Problems are mirrored in the com.github.lolgab.mill.mima package instead and the com.typesafe.tools.mima.core package

0.0.9

• Support Mill 0.10

0.0.8

• Correct hint in error message to match plugin's ProblemFilter class

0.0.7

• Support Mill 0.10.0-M5

0.0.6

• Support Mill 0.10.0-M4

0.0.5

• Add mimaExcludeAnnotations target
• Bump MiMa to 1.0.1
• Fix mill-scalalib dependency to be in compileIvyDeps

0.0.4

• Add support to resolve multiple previous artifacts
• Add mimaPreviousVersions target
• Redefine prepareOffline to include MiMa artifacts

0.0.3

• Support problem filters

0.0.2

• Change artifact name from mima_mill0.9 to mill-mima_mill0.9

0.0.1

First release