Merge pull request #1533 from sbt/fix/1530

Fixes #1530. Fixes NPE by using IO.listFiles

notes/0.13.6.md

@@ -47,6 +47,7 @@
   [1516]: https://github.com/sbt/sbt/pull/1516
   [1465]: https://github.com/sbt/sbt/issues/1465
   [1524]: https://github.com/sbt/sbt/issues/1524
+  [1530]: https://github.com/sbt/sbt/issues/1530
 
   [@dansanduleac]: https://github.com/dansanduleac
   [@2m]: https://github.com/2m
@@ -108,7 +109,7 @@
 - Fixes `build.sbt` errors causing `ArrayIndexOutOfBoundsException` due to invalid source in position. [#1181][1181] by [@eed3si9n][@eed3si9n]
 - Fixes config-classes leak in loading build files. [#1524][1524] by [@jsuereth][@jsuereth]
 - Fixes name-conflicts in hashed settings class files. [#1465][1465] by [@jsuereth][@jsuereth]
-
+- Fixes `NullPointerError` in tab completion by `FileExamples`. [#1530][1530] by [@eed3si9n][@eed3si9n]
 
 ### Maven Central Repository defaults to HTTPS
 

util/complete/src/main/scala/sbt/complete/ExampleSource.scala

@@ -1,7 +1,7 @@
 package sbt.complete
 
 import java.io.File
-import sbt.IO._
+import sbt.IO
 
 /**
  * These sources of examples are used in parsers for user input completion. An example of such a source is the
@@ -48,9 +48,9 @@ class FileExamples(base: File, prefix: String = "") extends ExampleSource {
   override def withAddedPrefix(addedPrefix: String): FileExamples = new FileExamples(base, prefix + addedPrefix)
 
   protected def files(directory: File): Stream[String] = {
-    val childPaths = directory.listFiles().toStream
-    val prefixedDirectChildPaths = childPaths.map(relativize(base, _).get).filter(_ startsWith prefix)
-    val dirsToRecurseInto = childPaths.filter(_.isDirectory).map(relativize(base, _).get).filter(dirStartsWithPrefix)
+    val childPaths = IO.listFiles(directory).toStream
+    val prefixedDirectChildPaths = childPaths map { IO.relativize(base, _).get } filter { _ startsWith prefix }
+    val dirsToRecurseInto = childPaths filter { _.isDirectory } map { IO.relativize(base, _).get } filter { dirStartsWithPrefix }
     prefixedDirectChildPaths append dirsToRecurseInto.flatMap(dir => files(new File(base, dir)))
   }
 

util/complete/src/test/scala/sbt/complete/FileExamplesTest.scala

@@ -80,8 +80,7 @@ class FileExamplesTest extends Specification {
       (childDirectories ++ nestedDirectories).map(_.mkdirs())
       (childFiles ++ nestedFiles).map(_.createNewFile())
 
-      // NOTE: Creating a new file here because `tempDir.listFiles()` returned an empty list.
-      baseDir = new File(tempDir.getCanonicalPath)
+      baseDir = tempDir
     }
 
     private def toChildFiles(baseDir: File, files: List[String]): List[File] = files.map(new File(baseDir, _))