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Add tests for Channel closed with an exception #4517

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00fc86a
add tests, replace Enum.values() with .entries, add *toList* samples
murfel Sep 2, 2025
4a7c83c
remove irrelevant tests
murfel Nov 10, 2025
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24 changes: 13 additions & 11 deletions kotlinx-coroutines-core/common/test/channels/BasicOperationsTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -8,31 +8,31 @@ class BasicOperationsTest : TestBase() {
@Test
fun testSimpleSendReceive() = runTest {
// Parametrized common test :(
TestChannelKind.values().forEach { kind -> testSendReceive(kind, 20) }
TestChannelKind.entries.forEach { kind -> testSendReceive(kind, 20) }
}

@Test
fun testTrySendToFullChannel() = runTest {
TestChannelKind.values().forEach { kind -> testTrySendToFullChannel(kind) }
TestChannelKind.entries.forEach { kind -> testTrySendToFullChannel(kind) }
}

@Test
fun testTrySendAfterClose() = runTest {
TestChannelKind.values().forEach { kind -> testTrySendAfterClose(kind) }
TestChannelKind.entries.forEach { kind -> testTrySendAfterClose(kind) }
}

@Test
fun testSendAfterClose() = runTest {
TestChannelKind.values().forEach { kind -> testSendAfterClose(kind) }
TestChannelKind.entries.forEach { kind -> testSendAfterClose(kind) }
}

@Test
fun testReceiveCatching() = runTest {
TestChannelKind.values().forEach { kind -> testReceiveCatching(kind) }
TestChannelKind.entries.forEach { kind -> testReceiveCatching(kind) }
}

@Test
fun testInvokeOnClose() = TestChannelKind.values().forEach { kind ->
fun testInvokeOnClose() = TestChannelKind.entries.forEach { kind ->
reset()
val channel = kind.create<Int>()
channel.invokeOnClose {
Expand All @@ -48,7 +48,7 @@ class BasicOperationsTest : TestBase() {
}

@Test
fun testInvokeOnClosed() = TestChannelKind.values().forEach { kind ->
fun testInvokeOnClosed() = TestChannelKind.entries.forEach { kind ->
reset()
expect(1)
val channel = kind.create<Int>()
Expand All @@ -59,7 +59,7 @@ class BasicOperationsTest : TestBase() {
}

@Test
fun testMultipleInvokeOnClose() = TestChannelKind.values().forEach { kind ->
fun testMultipleInvokeOnClose() = TestChannelKind.entries.forEach { kind ->
reset()
val channel = kind.create<Int>()
channel.invokeOnClose { expect(3) }
Expand All @@ -71,14 +71,16 @@ class BasicOperationsTest : TestBase() {
}

@Test
fun testIterator() = runTest {
TestChannelKind.values().forEach { kind ->
fun testIteratorHasNextMustPrecedeNext() = runTest {
TestChannelKind.entries.forEach { kind ->
val channel = kind.create<Int>()
val iterator = channel.iterator()
assertFailsWith<IllegalStateException> { iterator.next() }
channel.close()
assertFailsWith<IllegalStateException> { iterator.next() }
assertFalse(iterator.hasNext())
assertFailsWith<NoSuchElementException> { iterator.next() }
assertFailsWith<IllegalStateException> { iterator.next() }
}
}

Expand Down Expand Up @@ -109,7 +111,7 @@ class BasicOperationsTest : TestBase() {
try {
expect(2)
channel.close()
} catch (e: TestException) {
} catch (_: TestException) {
expect(4)
}
}
Expand Down
123 changes: 123 additions & 0 deletions kotlinx-coroutines-core/common/test/channels/ClosedChannelTest.kt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,123 @@
package kotlinx.coroutines.channels

import kotlinx.coroutines.testing.*
import kotlin.test.*

class ClosedChannelTest : TestBase() {
/**
* Iterator.
*/

@Test
fun testIteratorClosedHasNextFalse() = runTest {
TestChannelKind.entries.forEach { kind ->
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@dkhalanskyjb dkhalanskyjb Sep 17, 2025

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Proposal:

    fun TestChannelKind.Companion.runTestForEach(
        testBody: suspend CoroutineScope.(TestChannelKind) -> Unit
    ): TestResult = runTest {
        TestChannelKind.entries.forEach { kind ->
            testBody(kind)
        }
    }

May be more convenient, with how often this pattern occurs.

val channel = kind.create<Int>()
val iterator = channel.iterator()
channel.close()
assertFalse(iterator.hasNext())
}
}

@Test
fun testIteratorClosedWithExceptionHasNextThrows() = runTest {
TestChannelKind.entries.forEach { kind ->
val channel = kind.create<Int>()
val iterator = channel.iterator()
channel.close(TestException())
assertFailsWith<TestException> { (iterator.hasNext()) }
}
}

@Test
fun testClosedToListOk() = runTest {
TestChannelKind.entries.forEach { kind ->
val channel = kind.create<Int>()
channel.close()
channel.toList()
}
}

/**
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@dkhalanskyjb dkhalanskyjb Sep 17, 2025

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This syntax means the comment is a KDoc and refers to the entity directly below it. To make this a normal multiline comment for separating groups of tests, use /*.

That said, I think the separation is easy to break accidentally. Why not introduce separate classes to make this more robust?

class ClosedChannelTest: TestBase() {
    /**
     * Properties.
     *
     * Properties stay the same regardless of whether the channel was closed with or without exception.
     */
    class PropertiesTests: TestBase() {
        
    }
}

* Properties.
*
* Properties stay the same regardless of whether the channel was closed with or without exception.
*/

@Test
fun testClosedIsClosedForReceive() = runTest {
TestChannelKind.entries.forEach { kind ->
val channel = kind.create<Int>()
assertFalse(channel.isClosedForReceive)
channel.close()
assertTrue(channel.isClosedForReceive)
}
}

@Test
fun testClosedWithExceptionIsClosedForReceive() = runTest {
TestChannelKind.entries.forEach { kind ->
val channel = kind.create<Int>()
assertFalse(channel.isClosedForReceive)
channel.close(TestException())
assertTrue(channel.isClosedForReceive)
}
}

@Test
fun testClosedIsEmptyFalse() = runTest {
TestChannelKind.entries.forEach { kind ->
val channel = kind.create<Int>()
assertTrue(channel.isEmpty)
assertFalse(channel.isClosedForReceive)
channel.close()
// NB! Not obvious.
assertFalse(channel.isEmpty)
assertTrue(channel.isClosedForReceive)
}
}

@Test
fun testClosedWithExceptionIsEmptyFalse() = runTest {
TestChannelKind.entries.forEach { kind ->
val channel = kind.create<Int>()
assertTrue(channel.isEmpty)
assertFalse(channel.isClosedForReceive)
channel.close(TestException())
assertFalse(channel.isEmpty)
assertTrue(channel.isClosedForReceive)
}
}

@Test
fun testSendClosedReceiveIsEmptyFalse() = runTest {
val channel = Channel<Int>(1)
assertTrue(channel.isEmpty)
assertFalse(channel.isClosedForReceive)
channel.send(1)
assertFalse(channel.isEmpty)
assertFalse(channel.isClosedForReceive)
channel.close()
assertFalse(channel.isEmpty)
assertFalse(channel.isClosedForReceive)
channel.receive()
assertFalse(channel.isEmpty)
assertTrue(channel.isClosedForReceive)
}

@Test
fun testSendClosedWithExceptionReceiveIsEmptyFalse() = runTest {
val channel = Channel<Int>(1)
assertTrue(channel.isEmpty)
assertFalse(channel.isClosedForReceive)
channel.send(1)
assertFalse(channel.isEmpty)
assertFalse(channel.isClosedForReceive)
channel.close(TestException())
assertFalse(channel.isEmpty)
assertFalse(channel.isClosedForReceive)
channel.receive()
assertFalse(channel.isEmpty)
assertTrue(channel.isClosedForReceive)
}

}