From 334517aba85eca4d9398e76db9948d65abb04288 Mon Sep 17 00:00:00 2001
From: Guillaume Martres <smarter@ubuntu.com>
Date: Tue, 14 Mar 2017 16:53:06 +0100
Subject: [PATCH] Fix #3013: ScriptedPlugin: Add support for paginated tests

This was already supported in the internal Scripted used by sbt but not
in the ScriptedPlugin. This is fixed by just copy-pasting the modified
parser. We will have to wait for sbt itself to be built using an sbt
with the upgraded ScriptedPlugin to be able to avoid the code duplication.
---
 notes/0.13.14/paginate_scripted_tests.md      | 12 +++++
 project/Scripted.scala                        |  2 +
 .../src/main/scala/sbt/ScriptedPlugin.scala   | 47 +++++++++++++++----
 3 files changed, 53 insertions(+), 8 deletions(-)
 create mode 100644 notes/0.13.14/paginate_scripted_tests.md

diff --git a/notes/0.13.14/paginate_scripted_tests.md b/notes/0.13.14/paginate_scripted_tests.md
new file mode 100644
index 000000000..8ffdae83f
--- /dev/null
+++ b/notes/0.13.14/paginate_scripted_tests.md
@@ -0,0 +1,12 @@
+### Improvements
+
+- ScriptedPlugin: Add the ability to paginate scripted tests.
+  It is now possible to run a subset of scripted tests in a directory at once,
+  for example:
+  ```
+  scripted source-dependencies/*1of3
+  ```
+  Will create three pages and run page 1. This is especially useful when running
+  scripted tests on a CI, to benefit from the available parallelism.
+  [3013]: https://github.com/sbt/sbt/pull/3013
+  [@smarter]: https://github.com/smarter
diff --git a/project/Scripted.scala b/project/Scripted.scala
index 80b1ac8c1..4f89c4cff 100644
--- a/project/Scripted.scala
+++ b/project/Scripted.scala
@@ -37,6 +37,8 @@ object Scripted {
   import DefaultParsers._
   // Paging, 1-index based.
   case class ScriptedTestPage(page: Int, total: Int)
+  // FIXME: Duplicated with ScriptedPlugin.scriptedParser, this can be
+  // avoided once we upgrade build.properties to 0.13.14
   def scriptedParser(scriptedBase: File): Parser[Seq[String]] =
     {
       val scriptedFiles: NameFilter = ("test": NameFilter) | "pending"
diff --git a/scripted/plugin/src/main/scala/sbt/ScriptedPlugin.scala b/scripted/plugin/src/main/scala/sbt/ScriptedPlugin.scala
index eae62b316..896277515 100644
--- a/scripted/plugin/src/main/scala/sbt/ScriptedPlugin.scala
+++ b/scripted/plugin/src/main/scala/sbt/ScriptedPlugin.scala
@@ -62,20 +62,51 @@ object ScriptedPlugin extends AutoPlugin {
       m.getClass.getMethod("run", classOf[File], classOf[Boolean], classOf[Array[String]], classOf[File], classOf[Array[String]])
   }
 
-  private def scriptedParser(scriptedBase: File): Parser[Seq[String]] =
+  import DefaultParsers._
+  case class ScriptedTestPage(page: Int, total: Int)
+
+  private[sbt] def scriptedParser(scriptedBase: File): Parser[Seq[String]] =
     {
-      import DefaultParsers._
-      val pairs = (scriptedBase * AllPassFilter * AllPassFilter * "test").get map { (f: File) =>
+
+      val scriptedFiles: NameFilter = ("test": NameFilter) | "pending"
+      val pairs = (scriptedBase * AllPassFilter * AllPassFilter * scriptedFiles).get map { (f: File) =>
         val p = f.getParentFile
         (p.getParentFile.getName, p.getName)
       }
-      val pairMap = pairs.groupBy(_._1).mapValues(_.map(_._2).toSet)
+      val pairMap = pairs.groupBy(_._1).mapValues(_.map(_._2).toSet);
 
       val id = charClass(c => !c.isWhitespace && c != '/').+.string
-      val groupP = token(id.examples(pairMap.keySet)) <~ token('/')
-      def nameP(group: String) = token("*".id | id.examples(pairMap(group)))
-      val testID = for (group <- groupP; name <- nameP(group)) yield (group, name)
-      (token(Space) ~> matched(testID)).*
+      val groupP = token(id.examples(pairMap.keySet.toSet)) <~ token('/')
+
+      // A parser for page definitions
+      val pageP: Parser[ScriptedTestPage] = ("*" ~ NatBasic ~ "of" ~ NatBasic) map {
+        case _ ~ page ~ _ ~ total => ScriptedTestPage(page, total)
+      }
+      // Grabs the filenames from a given test group in the current page definition.
+      def pagedFilenames(group: String, page: ScriptedTestPage): Seq[String] = {
+        val files = pairMap(group).toSeq.sortBy(_.toLowerCase)
+        val pageSize = files.size / page.total
+        // The last page may loose some values, so we explicitly keep them
+        val dropped = files.drop(pageSize * (page.page - 1))
+        if (page.page == page.total) dropped
+        else dropped.take(pageSize)
+      }
+      def nameP(group: String) = {
+        token("*".id | id.examples(pairMap(group)))
+      }
+      val PagedIds: Parser[Seq[String]] =
+        for {
+          group <- groupP
+          page <- pageP
+          files = pagedFilenames(group, page)
+          // TODO -  Fail the parser if we don't have enough files for the given page size
+          //if !files.isEmpty
+        } yield files map (f => group + '/' + f)
+
+      val testID = (for (group <- groupP; name <- nameP(group)) yield (group, name))
+      val testIdAsGroup = matched(testID) map (test => Seq(test))
+      //(token(Space) ~> matched(testID)).*
+      (token(Space) ~> (PagedIds | testIdAsGroup)).* map (_.flatten)
     }
 
   def scriptedTask: Initialize[InputTask[Unit]] = Def.inputTask {