Enable MIMA in build, fix binary incompatibility (#195)

* enable mima

* binary incompatibility fix

* revert ring change

* bumped version, disabled mima

* cache travis

* add ignored

.travis.yml

@@ -31,10 +31,14 @@ cache:
   - $HOME/.ivy2/cache
   - $HOME/.nvm
 
-script: ./sbt ++$TRAVIS_SCALA_VERSION clean coreJS/test lawsJS/test && ./sbt ++$TRAVIS_SCALA_VERSION clean coverage coreJVM/test lawsJVM/test coverageReport && ./sbt ++$TRAVIS_SCALA_VERSION core:mimaReportBinaryIssues && ./sbt ++$TRAVIS_SCALA_VERSION docs/makeMicrosite
+script:
+  - ./sbt ++$TRAVIS_SCALA_VERSION clean coreJS/test lawsJS/test
+  - ./sbt ++$TRAVIS_SCALA_VERSION clean coverage coreJVM/test lawsJVM/test coverageReport mimaReportBinaryIssues
+  - ./sbt ++$TRAVIS_SCALA_VERSION docs/makeMicrosite
 
 after_success:
   - bash <(curl -s https://codecov.io/bash)
+
 notifications:
   irc:
     channels:

build.sbt

@@ -3,18 +3,17 @@ import sbtunidoc.Plugin.UnidocKeys._
 import ReleaseTransformations._
 import com.typesafe.sbt.SbtGhPages.GhPagesKeys._
 import com.typesafe.tools.mima.plugin.MimaPlugin.mimaDefaultSettings
-import com.typesafe.tools.mima.plugin.MimaKeys.previousArtifact
 
 lazy val scalaCheckVersion = "1.13.4"
-lazy val scalaTestVersion = "3.0.0"
+lazy val scalaTestVersion = "3.0.1"
 lazy val disciplineVersion = "0.7.2"
 lazy val catsVersion = "0.8.1"
 lazy val catalystsVersion = "0.0.5"
 
 lazy val buildSettings = Seq(
   organization := "org.typelevel",
-  scalaVersion := "2.12.0",
-  crossScalaVersions := Seq("2.10.6", "2.11.8", "2.12.0")
+  scalaVersion := "2.12.1",
+  crossScalaVersions := Seq("2.10.6", "2.11.8", "2.12.1")
 )
 
 lazy val commonSettings = Seq(
@@ -101,12 +100,27 @@ lazy val aggregate = project.in(file("."))
   .aggregate(coreJS, lawsJS)
   .dependsOn(coreJS, lawsJS)
 
+val binaryCompatibleVersion = "0.6.0"
+
+/**
+  * Empty this each time we publish a new version (and bump the minor number)
+  */
+val ignoredABIProblems = {
+  import com.typesafe.tools.mima.core._
+  import com.typesafe.tools.mima.core.ProblemFilters._
+  Seq(
+    exclude[ReversedMissingMethodProblem]("algebra.ring.RingFunctions.defaultFromDouble")
+  )
+}
+
 lazy val core = crossProject
   .crossType(CrossType.Pure)
   .settings(moduleName := "algebra")
   .settings(mimaDefaultSettings: _*)
-  // TODO: update this to a published stable version, e.g. 0.4.0
-  //.settings(previousArtifact := Some("org.spire-math" %% "algebra" % "0.3.1"))
+  .settings(
+    mimaPreviousArtifacts := Set("org.typelevel" %% "algebra" % binaryCompatibleVersion),
+    mimaBinaryIssueFilters ++= ignoredABIProblems
+  )
   .settings(libraryDependencies ++= Seq(
     "org.typelevel" %%% "cats-kernel" % catsVersion,
     "org.scalacheck" %%% "scalacheck" % scalaCheckVersion % "test",
@@ -121,6 +135,9 @@ lazy val laws = crossProject
   .crossType(CrossType.Pure)
   .dependsOn(core)
   .settings(moduleName := "algebra-laws")
+  .settings(mimaDefaultSettings: _*)
+  .settings(mimaPreviousArtifacts :=
+    Set("org.typelevel" %% "algebra-laws" % binaryCompatibleVersion))
   .settings(algebraSettings: _*)
   .settings(libraryDependencies ++= Seq(
     "org.typelevel" %%% "cats-kernel-laws" % catsVersion,

core/src/main/scala/algebra/instances/bigDecimal.scala

@@ -8,11 +8,12 @@ import algebra.ring._
 package object bigDecimal extends BigDecimalInstances
 
 trait BigDecimalInstances extends cats.kernel.instances.BigDecimalInstances {
-  implicit val bigDecimalAlgebra: BigDecimalAlgebra =
-    new BigDecimalAlgebra(MathContext.UNLIMITED)
+  implicit val bigDecimalAlgebra: BigDecimalAlgebra = new BigDecimalAlgebra()
 }
 
 class BigDecimalAlgebra(mc: MathContext) extends Field[BigDecimal] with Serializable {
+  def this() = this(MathContext.UNLIMITED)
+
   val zero: BigDecimal = BigDecimal(0, mc)
   val one: BigDecimal = BigDecimal(1, mc)
 

project/plugins.sbt

@@ -5,6 +5,6 @@ addSbtPlugin("com.jsuereth"      % "sbt-pgp"         % "1.0.0")
 addSbtPlugin("org.xerial.sbt"    % "sbt-sonatype"    % "1.1")
 addSbtPlugin("com.typesafe.sbt"  % "sbt-ghpages"     % "0.5.4")
 addSbtPlugin("org.scala-js"      % "sbt-scalajs"     % "0.6.13")
-addSbtPlugin("com.typesafe"      % "sbt-mima-plugin" % "0.1.11")
+addSbtPlugin("com.typesafe"      % "sbt-mima-plugin" % "0.1.12")
 addSbtPlugin("org.scoverage"     % "sbt-scoverage"   % "1.5.0")
 addSbtPlugin("pl.project13.scala" % "sbt-jmh"        % "0.2.18")

version.sbt

@@ -1 +1 @@
-version in ThisBuild := "0.6.1-SNAPSHOT"
+version in ThisBuild := "0.7.0-SNAPSHOT"