Added test for stack-trace recovery in JobCancellationException

Fixes #950

Author: elizarov

kotlinx-coroutines-core/jvm/test/exceptions/StackTraceRecoveryNestedChannelsTest.kt

@@ -133,4 +133,40 @@ class StackTraceRecoveryNestedChannelsTest : TestBase() {
         finish(3)
         deferred.await()
     }
+
+    // See https://github.com/Kotlin/kotlinx.coroutines/issues/950
+    @Test
+    fun testCancelledOffer() = runTest {
+        expect(1)
+        val job = Job()
+        val actor = actor<Int>(job, Channel.UNLIMITED) {
+            consumeEach {
+                expectUnreached() // is cancelled before offer
+            }
+        }
+        job.cancel()
+        try {
+            actor.offer(1)
+        } catch (e: Exception) {
+            verifyStackTrace(e,
+                "kotlinx.coroutines.JobCancellationException: Job was cancelled; job=JobImpl{Cancelling}@3af42ad0\n" +
+                        "\t(Coroutine boundary)\n" +
+                        "\tat kotlinx.coroutines.channels.AbstractSendChannel.offer(AbstractChannel.kt:186)\n" +
+                        "\tat kotlinx.coroutines.channels.ChannelCoroutine.offer(ChannelCoroutine.kt)\n" +
+                        "\tat kotlinx.coroutines.exceptions.StackTraceRecoveryNestedChannelsTest\$testCancelledOffer\$1.invokeSuspend(StackTraceRecoveryNestedChannelsTest.kt:150)\n" +
+                    "Caused by: kotlinx.coroutines.JobCancellationException: Job was cancelled; job=JobImpl{Cancelling}@3af42ad0\n",
+                    // ... java.lang.* stuff snipped here ...
+                        "\tat kotlinx.coroutines.JobCancellationException.<init>(Exceptions.kt:44)\n" +
+                        "\tat kotlinx.coroutines.JobSupport.createJobCancellationException(JobSupport.kt:631)\n" +
+                        "\tat kotlinx.coroutines.JobSupport.createCauseException(JobSupport.kt:656)\n" +
+                        "\tat kotlinx.coroutines.JobSupport.cancelMakeCompleting(JobSupport.kt:620)\n" +
+                        "\tat kotlinx.coroutines.JobSupport.cancelImpl(JobSupport.kt:608)\n" +
+                        "\tat kotlinx.coroutines.JobSupport.cancelInternal(JobSupport.kt:583)\n" +
+                        "\tat kotlinx.coroutines.JobSupport.cancel(JobSupport.kt:571)\n" +
+                        "\tat kotlinx.coroutines.Job\$DefaultImpls.cancel\$default(Job.kt:164)\n" +
+                        "\tat kotlinx.coroutines.exceptions.StackTraceRecoveryNestedChannelsTest\$testCancelledOffer\$1.invokeSuspend(StackTraceRecoveryNestedChannelsTest.kt:148)"
+            )
+            finish(2)
+        }
+    }
 }

kotlinx-coroutines-core/jvm/test/exceptions/Stacktraces.kt

@@ -6,10 +6,12 @@ import kotlin.test.*
 public fun verifyStackTrace(e: Throwable, vararg traces: String) {
     val stacktrace = toStackTrace(e)
     traces.forEach {
-        assertTrue(
-            stacktrace.trimStackTrace().contains(it.trimStackTrace()),
-            "\nExpected trace element:\n$it\n\nActual stacktrace:\n$stacktrace"
-        )
+        val actual = stacktrace.trimStackTrace()
+        val expected = it.trimStackTrace()
+        if (!actual.contains(expected)) {
+            // A more readable error message would be produced by assertEquals
+            assertEquals(expected, actual, "Actual trace does not contain expected one")
+        }
     }
 
     val causes = stacktrace.count("Caused by")
@@ -23,11 +25,11 @@ public fun toStackTrace(t: Throwable): String {
     return sw.toString()
 }
 
-public fun String.trimStackTrace(): String {
-    return applyBackspace(trimIndent().replace(Regex(":[0-9]+"), "")
+public fun String.trimStackTrace(): String =
+    applyBackspace(replace(Regex(":[0-9]+"), "")
         .replace("kotlinx_coroutines_core_main", "") // yay source sets
         .replace("kotlinx_coroutines_core", ""))
-}
+        .replace(Regex("@[0-9a-f]+"), "") // hex addresses in debug toStrings
 
 public fun applyBackspace(line: String): String {
     val array = line.toCharArray()