test/junit/scala/collection/mutable/HashMapTest.scala


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package scala.collection
package mutable

import org.junit.Assert._
import org.junit.Test
import org.junit.runner.RunWith
import org.junit.runners.JUnit4

@RunWith(classOf[JUnit4])
class HashMapTest {

  @Test
  def getOrElseUpdate_mutationInCallback() {
    val hm = new mutable.HashMap[String, String]()
    // add enough elements to resize the hash table in the callback
    def add() = 1 to 100000 foreach (i => hm(i.toString) = "callback")
    hm.getOrElseUpdate("0", {
      add()
      ""
    })
    assertEquals(Some(""), hm.get("0"))
  }

  @Test
  def getOrElseUpdate_evalOnce(): Unit = {
    var i = 0
    val hm = new mutable.HashMap[Int, Int]()
    hm.getOrElseUpdate(0, {i += 1; i})
    assertEquals(1, hm(0))
  }

  @Test
  def getOrElseUpdate_noEval(): Unit = {
    val hm = new mutable.HashMap[Int, Int]()
    hm.put(0, 0)
    hm.getOrElseUpdate(0, throw new AssertionError())
  }
}