ConcurrentUtilsTest: fix testRunSingle_SameKey_Parallel (bitfireAT/davx5#494)

import at.bitfire.davdroid.util.ConcurrentUtils

import org.junit.Assert.assertEquals

import org.junit.Assert.assertFalse

import org.junit.Assert.assertTrue

import org.junit.Assert.fail

import org.junit.Test

import java.util.concurrent.atomic.AtomicInteger

import kotlin.concurrent.thread

class ConcurrentUtilsTest {

        var nrCalled = AtomicInteger()

        val threads = mutableListOf<Thread>()

        for (i in 0 until 10)

            threads += Thread() {

            threads += thread {

                ConcurrentUtils.runSingle(i) {

                    nrCalled.incrementAndGet()

                    Thread.sleep(100)

                }

            }.apply { start() }

            }

        threads.forEach { it.join() }

        assertEquals(10, nrCalled.get())

    }

    }

    @Test

    fun testRunSingle_SameKey_Parallel() {

    fun testRunSingle_SameKey_Nested() {

        val key = "a"

        val nrCalled = AtomicInteger()

        val threads = mutableListOf<Thread>()

        for (i in 0 until 10)

            threads += Thread() {

        var outerBlockExecuted = false

        ConcurrentUtils.runSingle(key) {

                    nrCalled.incrementAndGet()

                    Thread.sleep(100)

            outerBlockExecuted = true

            // Now a code block with the key is already running, further ones should be ignored

            assertFalse(ConcurrentUtils.runSingle(key) {

                fail("Shouldn't have been called")

            })

        }

            }.apply { start() }

        threads.forEach { it.join() }

        assertEquals(1, nrCalled.get())

        assertTrue(outerBlockExecuted)

    }

}

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