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Diffstat (limited to 'test/junit/scala/collection/immutable/StreamTest.scala')
-rw-r--r-- | test/junit/scala/collection/immutable/StreamTest.scala | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/test/junit/scala/collection/immutable/StreamTest.scala b/test/junit/scala/collection/immutable/StreamTest.scala new file mode 100644 index 0000000000..1b257aabc4 --- /dev/null +++ b/test/junit/scala/collection/immutable/StreamTest.scala @@ -0,0 +1,126 @@ +package scala.collection.immutable + +import org.junit.runner.RunWith +import org.junit.runners.JUnit4 +import org.junit.Test +import org.junit.Assert._ + +import scala.ref.WeakReference +import scala.util.Try + +@RunWith(classOf[JUnit4]) +class StreamTest { + + @Test + def t6727_and_t6440_and_8627(): Unit = { + assertTrue(Stream.continually(()).filter(_ => true).take(2) == Seq((), ())) + assertTrue(Stream.continually(()).filterNot(_ => false).take(2) == Seq((), ())) + assertTrue(Stream(1,2,3,4,5).filter(_ < 4) == Seq(1,2,3)) + assertTrue(Stream(1,2,3,4,5).filterNot(_ > 4) == Seq(1,2,3,4)) + assertTrue(Stream.from(1).filter(_ > 4).take(3) == Seq(5,6,7)) + assertTrue(Stream.from(1).filterNot(_ <= 4).take(3) == Seq(5,6,7)) + } + + /** Test helper to verify that the given Stream operation allows + * GC of the head during processing of the tail. + */ + def assertStreamOpAllowsGC(op: (=> Stream[Int], Int => Unit) => Any, f: Int => Unit): Unit = { + val msgSuccessGC = "GC success" + val msgFailureGC = "GC failure" + + // A stream of 500 elements at most. We will test that the head can be collected + // while processing the tail. After each element we will GC and wait 10 ms, so a + // failure to collect will take roughly 5 seconds. + val ref = WeakReference( Stream.from(1).take(500) ) + + def gcAndThrowIfCollected(n: Int): Unit = { + System.gc() // try to GC + Thread.sleep(10) // give it 10 ms + if (ref.get.isEmpty) throw new RuntimeException(msgSuccessGC) // we're done if head collected + f(n) + } + + val res = Try { op(ref(), gcAndThrowIfCollected) }.failed // success is indicated by an + val msg = res.map(_.getMessage).getOrElse(msgFailureGC) // exception with expected message + // failure is indicated by no + assertTrue(msg == msgSuccessGC) // exception, or one with different message + } + + @Test + def foreach_allows_GC() { + assertStreamOpAllowsGC(_.foreach(_), _ => ()) + } + + @Test + def filter_all_foreach_allows_GC() { + assertStreamOpAllowsGC(_.filter(_ => true).foreach(_), _ => ()) + } + + @Test // SI-8990 + def withFilter_after_first_foreach_allows_GC: Unit = { + assertStreamOpAllowsGC(_.withFilter(_ > 1).foreach(_), _ => ()) + } + + @Test // SI-8990 + def withFilter_after_first_withFilter_foreach_allows_GC: Unit = { + assertStreamOpAllowsGC(_.withFilter(_ > 1).withFilter(_ < 100).foreach(_), _ => ()) + } + + @Test // SI-8990 + def withFilter_can_retry_after_exception_thrown_in_filter: Unit = { + // use mutable state to control an intermittent failure in filtering the Stream + var shouldThrow = true + + val wf = Stream.from(1).take(10).withFilter { n => + if (shouldThrow && n == 5) throw new RuntimeException("n == 5") else n > 5 + } + + assertTrue( Try { wf.map(identity) }.isFailure ) // throws on n == 5 + + shouldThrow = false // won't throw next time + + assertTrue( wf.map(identity).length == 5 ) // success instead of NPE + } + + /** Test helper to verify that the given Stream operation is properly lazy in the tail */ + def assertStreamOpLazyInTail(op: (=> Stream[Int]) => Stream[Int], expectedEvaluated: List[Int]): Unit = { + // mutable state to record every strict evaluation + var evaluated: List[Int] = Nil + + def trackEffectsOnNaturals: Stream[Int] = { + def loop(i: Int): Stream[Int] = { evaluated ++= List(i); i #:: loop(i + 1) } + loop(1) + } + + // call op on a stream which records every strict evaluation + val result = op(trackEffectsOnNaturals) + + assertTrue( evaluated == expectedEvaluated ) + } + + @Test // SI-9134 + def filter_map_properly_lazy_in_tail: Unit = { + assertStreamOpLazyInTail(_.filter(_ % 2 == 0).map(identity), List(1, 2)) + } + + @Test // SI-9134 + def withFilter_map_properly_lazy_in_tail: Unit = { + assertStreamOpLazyInTail(_.withFilter(_ % 2 == 0).map(identity), List(1, 2)) + } + + @Test + def test_si9379() { + class Boom { + private var i = -1 + def inc = { + i += 1 + if (i > 1000) throw new NoSuchElementException("Boom! Too many elements!") + i + } + } + val b = new Boom + val s = Stream.continually(b.inc) + // zipped.toString must allow s to short-circuit evaluation + assertTrue((s, s).zipped.toString contains s.toString) + } +} |