add support for sbt-assembly (#152)

* add support for sbt-assembly

* Move assembly override to separate autoplugin

Co-authored-by: Arnout Engelen <arnout@bzzt.net>

build.sbt

@@ -24,6 +24,7 @@ libraryDependencies += "org.scalatest" %% "scalatest" % "3.1.2" % "test"
 // Optional integration:
 addSbtPlugin("com.typesafe.sbt" %% "sbt-native-packager" % "1.7.3" % Provided)
 addSbtPlugin("io.crashbox" %% "sbt-gpg" % "0.2.1" % Provided)
+addSbtPlugin("com.eed3si9n" %% "sbt-assembly" % "0.14.10" % Provided)
 // addSbtPlugin("com.jsuereth" % "sbt-pgp" % sbtPgpVersion % Provided)
 
 licenses += ("MIT", url("https://opensource.org/licenses/MIT"))

src/main/scala/AssemblyHelpers.scala

@@ -0,0 +1,16 @@
+package net.bzzt.reproduciblebuilds
+
+import sbtassembly.{Assembly, AssemblyPlugin}
+import sbtassembly.AssemblyPlugin.autoImport.{Assembly => _, baseAssemblySettings => _, _}
+import sbt._
+import sbt.Keys._
+
+object AssemblyHelpers {
+  val plugin: Plugins.Basic = AssemblyPlugin
+
+  val settings: Seq[Setting[_]] =
+    Seq(
+      assembly := ReproducibleBuildsPlugin.postProcessJar(assembly.value)
+    )
+
+}

src/main/scala/ReproducibleBuildsAssemblyPlugin.scala

@@ -0,0 +1,21 @@
+package net.bzzt.reproduciblebuilds
+
+import scala.util.Try
+
+import sbt._
+import sbt.plugins.JvmPlugin
+
+object ReproducibleBuildsAssemblyPlugin extends AutoPlugin {
+  val assemblyPluginOnClasspath =
+    Try(getClass.getClassLoader.loadClass("sbtassembly.AssemblyPlugin")).isSuccess
+
+  override def requires: Plugins = 
+    if (assemblyPluginOnClasspath) AssemblyHelpers.plugin
+    else JvmPlugin
+
+  override def trigger = allRequirements
+
+  override def projectSettings = 
+    if (assemblyPluginOnClasspath) AssemblyHelpers.settings
+    else Seq.empty
+}

src/main/scala/ReproducibleBuildsPlugin.scala

@@ -30,6 +30,7 @@ object ReproducibleBuildsPlugin extends AutoPlugin {
   val gpgPluginOnClasspath =
     Try(getClass.getClassLoader.loadClass("io.crashbox.gpg.SbtGpg")).isSuccess
 
+
   override def requires: Plugins = JvmPlugin
 
   val ReproducibleBuilds = config("reproducible-builds")

src/sbt-test/sbt-reproducible-builds/assembly/build.sbt

@@ -0,0 +1,3 @@
+scalaVersion := "2.12.7"
+
+enablePlugins(ReproducibleBuildsPlugin)

src/sbt-test/sbt-reproducible-builds/assembly/project/build.properties

@@ -0,0 +1 @@
+sbt.version=1.3.12

src/sbt-test/sbt-reproducible-builds/assembly/project/plugins.sbt

@@ -0,0 +1,7 @@
+sys.props.get("plugin.version") match {
+  case Some(x) => addSbtPlugin("net.bzzt" % "sbt-reproducible-builds" % sys.props("plugin.version"))
+  case _ => sys.error("""|The system property 'plugin.version' is not defined.
+                         |Specify this property using the scriptedLaunchOpts -D.""".stripMargin)
+}
+
+addSbtPlugin("com.eed3si9n"  % "sbt-assembly" % "0.14.10")

src/sbt-test/sbt-reproducible-builds/assembly/src/main/scala/Main.scala

@@ -0,0 +1,5 @@
+package net.bzzt
+
+object Main extends App {
+  println("Hello, Reproducible World")
+}

src/sbt-test/sbt-reproducible-builds/assembly/test

@@ -0,0 +1,4 @@
+> assembly
+$ exists target/scala-2.12/assembly-assembly-0.1.0-SNAPSHOT.jar
+$ exists target/scala-2.12/stripped/assembly-assembly-0.1.0-SNAPSHOT.jar
+$ must-mirror target/scala-2.12/stripped/assembly-assembly-0.1.0-SNAPSHOT.jar expected/assembly-assembly-0.1.0-SNAPSHOT.jar