Merge pull request #4075 from som-snytt/issue/8835-junit

SI-8835 Iterator tests can be junit

2 files changed, 150 insertions, 3 deletions

diff --git a/test/junit/scala/collection/IteratorTest.scala b/test/junit/scala/collection/IteratorTest.scala
index b7a9805c9f..d5389afd0c 100644
--- a/test/junit/scala/collection/IteratorTest.scala
+++ b/test/junit/scala/collection/IteratorTest.scala
@@ -6,11 +6,14 @@ import org.junit.Test
 import org.junit.runner.RunWith
 import org.junit.runners.JUnit4
 
+import scala.tools.testing.AssertUtil._
+
+import Seq.empty
+
 @RunWith(classOf[JUnit4])
 class IteratorTest {
 
-  @Test
-  def groupedIteratorShouldNotAskForUnneededElement(): Unit = {
+  @Test def groupedIteratorShouldNotAskForUnneededElement(): Unit = {
     var counter = 0
     val it = new Iterator[Int] { var i = 0 ; def hasNext = { counter = i; true } ; def next = { i += 1; i } }
     val slidingIt = it sliding 2
@@ -25,4 +28,130 @@ class IteratorTest {
     slidingIt.next
     assertEquals("Counter should be one, that means we didn't look further than needed", 1, counter)
   }
+
+  @Test def dropDoesNotGrowStack(): Unit = {
+    def it = new Iterator[Throwable] { def hasNext = true ; def next = new Throwable }
+
+    assertEquals(it.drop(1).next.getStackTrace.length, it.drop(1).drop(1).next.getStackTrace.length)
+  }
+
+  @Test def dropIsChainable(): Unit = {
+    assertSameElements(1 to 4, Iterator from 0 take 5 drop 1)
+    assertSameElements(3 to 4, Iterator from 0 take 5 drop 3)
+    assertSameElements(empty,  Iterator from 0 take 5 drop 5)
+    assertSameElements(empty,  Iterator from 0 take 5 drop 10)
+    assertSameElements(0 to 4, Iterator from 0 take 5 drop 0)
+    assertSameElements(0 to 4, Iterator from 0 take 5 drop -1)
+    assertSameElements(2 to 8 by 2, Iterator from 0 take 5 drop 1 map (2 * _))
+    assertSameElements(2 to 8 by 2, Iterator from 0 take 5 map (2 * _) drop 1)
+    assertSameElements(3 to 4, Iterator from 0 take 5 drop 1 drop 2)
+    assertSameElements(3 to 4, Iterator from 0 take 5 drop 2 drop 1)
+  }
+
+  @Test def sliceIsChainable(): Unit = {
+    assertSameElements(3 to 6, Iterator from 0 slice (3, 7))
+    assertSameElements(empty,  Iterator from 0 slice (3, 3))
+    assertSameElements(0 to 2, Iterator from 0 slice (-1, 3))
+    assertSameElements(empty,  Iterator from 0 slice (3, -1))
+    assertSameElements(6 to 12 by 2, Iterator from 0 slice (3, 7) map (2 * _))
+    assertSameElements(6 to 12 by 2, Iterator from 0 map (2 * _) slice (3, 7))
+    assertSameElements(4 to 6, Iterator from 0 slice (3, 7) drop 1)
+    assertSameElements(4 to 7, Iterator from 0 drop 1 slice (3, 7))
+    assertSameElements(4 to 5, Iterator from 0 slice (3, 7) slice (1, 3))
+    assertSameElements(4 to 6, Iterator from 0 slice (3, 7) slice (1, 10))
+  }
+
+  // test/files/run/iterator-concat.scala
+  @Test def concatIsStackFriendly(): Unit = {
+    // Create `size` Function0s, each of which evaluates to an Iterator
+    // which produces 1. Then fold them over ++ to get a single iterator,
+    // which should sum to "size".
+    def mk(size: Int): Iterator[Int] = {
+      //val closures = (1 to size).toList.map(x => (() => Iterator(1)))
+      //closures.foldLeft(Iterator.empty: Iterator[Int])((res, f) => res ++ f())
+      List.fill(size)(() => Iterator(1)).foldLeft(Iterator.empty: Iterator[Int])((res, f) => res ++ f())
+    }
+    assertEquals(100,    mk(100).sum)
+    assertEquals(1000,   mk(1000).sum)
+    assertEquals(10000,  mk(10000).sum)
+    assertEquals(100000, mk(100000).sum)
+  }
+
+  @Test def from(): Unit = {
+    val it1 = Iterator.from(-1)
+    val it2 = Iterator.from(0, -1)
+    assertEquals(-1, it1.next())
+    assertEquals(0,  it2.next())
+  }
+  @Test def range(): Unit = {
+    assertEquals(5, Iterator.range(0, 10, 2).size)
+    assertEquals(0, Iterator.range(0, 10, -2).size)
+    assertEquals(5, Iterator.range(10, 0, -2).size)
+    assertEquals(0, Iterator.range(10, 0, 2).size)
+    assertEquals(1, Iterator.range(0, 10, 11).size)
+    assertEquals(10, Iterator.range(0, 10, 1).size)
+    assertEquals(10, Iterator.range(10, 0, -1).size)
+  }
+  @Test def range3(): Unit = {
+    val r1 = Iterator.range(0, 10)
+    assertTrue(r1 contains 5)
+    assertTrue(r1 contains 6)
+    assertFalse(r1 contains 4)
+    val r2a = Iterator.range(0, 10, 2)
+    assertFalse(r2a contains 5)
+    val r2b = Iterator.range(0, 10, 2)
+    assertTrue(r2b contains 6)
+    val r3 = Iterator.range(0, 10, 11)
+    assertFalse(r3 contains 5)
+    assertTrue(r3.isEmpty)
+  }
+  @Test def take(): Unit = {
+    assertEquals(10, (Iterator from 0 take 10).size)
+  }
+  @Test def foreach(): Unit = {
+    val it1 = Iterator.from(0) take 20
+    var n = 0
+    it1 foreach { n += _ }
+    assertEquals(190, n)
+  }
+  // ticket #429
+  @Test def fromArray(): Unit = {
+    val a = List(1, 2, 3, 4).toArray
+    var xs0 = a.iterator.toList;
+    var xs1 = a.slice(0, 1).iterator
+    var xs2 = a.slice(0, 2).iterator
+    var xs3 = a.slice(0, 3).iterator
+    var xs4 = a.slice(0, 4).iterator
+    assertEquals(14, xs0.size + xs1.size + xs2.size + xs3.size + xs4.size)
+  }
+  @Test def toSeq(): Unit = {
+    assertEquals("1x2x3x4x5", List(1, 2, 3, 4, 5).iterator.mkString("x"))
+  }
+  @Test def indexOf(): Unit = {
+    assertEquals(3, List(1, 2, 3, 4, 5).iterator.indexOf(4))
+    assertEquals(-1, List(1, 2, 3, 4, 5).iterator.indexOf(16))
+  }
+  @Test def indexWhere(): Unit = {
+    assertEquals(3, List(1, 2, 3, 4, 5).iterator.indexWhere { x: Int => x >= 4 })
+    assertEquals(-1, List(1, 2, 3, 4, 5).iterator.indexWhere { x: Int => x >= 16 })
+  }
+  // iterator-iterate-lazy.scala
+  // was java.lang.UnsupportedOperationException: tail of empty list
+  @Test def iterateIsSufficientlyLazy(): Unit = {
+    //Iterator.iterate((1 to 5).toList)(_.tail).takeWhile(_.nonEmpty).toList  // suffices
+    Iterator.iterate((1 to 5).toList)(_.tail).takeWhile(_.nonEmpty).map(_.head).toList
+  }
+  // SI-3516
+  @Test def toStreamIsSufficientlyLazy(): Unit = {
+    val results = collection.mutable.ListBuffer.empty[Int]
+    def mkIterator = (1 to 5).iterator map (x => { results += x ; x })
+    def mkInfinite = Iterator continually { results += 1 ; 1 }
+
+    // Stream is strict in its head so we should see 1 from each of them.
+    val s1 = mkIterator.toStream
+    val s2 = mkInfinite.toStream
+    // back and forth without slipping into nontermination.
+    results += (Stream from 1).toIterator.drop(10).toStream.drop(10).toIterator.next()
+    assertSameElements(List(1,1,21), results)
+  }
 }
diff --git a/test/junit/scala/tools/testing/AssertUtil.scala b/test/junit/scala/tools/testing/AssertUtil.scala
index 9b4833d46b..83a637783f 100644
--- a/test/junit/scala/tools/testing/AssertUtil.scala
+++ b/test/junit/scala/tools/testing/AssertUtil.scala
@@ -1,6 +1,11 @@
 package scala.tools
 package testing
 
+import org.junit.Assert
+import Assert.fail
+import scala.runtime.ScalaRunTime.stringOf
+import scala.collection.{ GenIterable, IterableLike }
+
 /** This module contains additional higher-level assert statements
  *  that are ultimately based on junit.Assert primitives.
  */
@@ -21,6 +26,19 @@ object AssertUtil {
           throw e
         else return
     }
-    throw new AssertionError("Expression did not throw!")
+    fail("Expression did not throw!")
   }
+
+  /** JUnit-style assertion for `IterableLike.sameElements`.
+   */
+  def assertSameElements[A, B >: A](expected: IterableLike[A, _], actual: GenIterable[B], message: String = ""): Unit =
+    if (!(expected sameElements actual))
+      fail(
+        f"${ if (message.nonEmpty) s"$message " else "" }expected:<${ stringOf(expected) }> but was:<${ stringOf(actual) }>"
+      )
+
+  /** Convenient for testing iterators.
+   */
+  def assertSameElements[A, B >: A](expected: IterableLike[A, _], actual: Iterator[B]): Unit =
+    assertSameElements(expected, actual.toList, "")
 }