Add mill-mima to check binary compatibility (#90)

Author: lolgab

.github/workflows/actions.yml

@@ -16,6 +16,17 @@ jobs:
           java-version: 8
       - name: Run tests
         run: ./mill -i __.publishArtifacts __.test
+  check-binary-compatibility:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 8
+      - name: Check Binary Compatibility
+        run: ./mill -i __.mimaReportBinaryIssues
 
   publish-sonatype:
     if: github.repository == 'com-lihaoyi/requests-scala' && contains(github.ref, 'refs/tags/')

build.sc

@@ -3,12 +3,15 @@ import mill.scalalib.publish.{Developer, License, PomSettings, VersionControl}
 import scalalib._
 import $ivy.`de.tototec::de.tobiasroeser.mill.vcs.version_mill0.9:0.1.1`
 import de.tobiasroeser.mill.vcs.version.VcsVersion
+import $ivy.`com.github.lolgab::mill-mima_mill0.9:0.0.4`
+import com.github.lolgab.mill.mima._
 
 val dottyVersion = Option(sys.props("dottyVersion"))
 
 object requests extends Cross[RequestsModule]((List("2.12.13", "2.13.5", "2.11.12", "3.0.0") ++ dottyVersion): _*)
-class RequestsModule(val crossScalaVersion: String) extends CrossScalaModule with PublishModule {
+class RequestsModule(val crossScalaVersion: String) extends CrossScalaModule with PublishModule with Mima {
   def publishVersion = VcsVersion.vcsState().format()
+  def mimaPreviousVersions = VcsVersion.vcsState().lastTag.toSeq
   def artifactName = "requests"
   def pomSettings = PomSettings(
     description = "Scala port of the popular Python Requests HTTP client",