diff --git a/compiler/testData/diagnostics/helpers/coroutines/CoroutineHelpers.kt b/compiler/testData/diagnostics/helpers/coroutines/CoroutineHelpers.kt
new file mode 100644
index 00000000000..fbba93231cd
--- /dev/null
+++ b/compiler/testData/diagnostics/helpers/coroutines/CoroutineHelpers.kt
@@ -0,0 +1,49 @@
+package helpers
+
+import kotlin.coroutines.*
+import kotlin.coroutines.intrinsics.*
+import kotlin.coroutines.jvm.internal.*
+
+fun <T> handleResultContinuation(x: (T) -> Unit): Continuation<T> = object: Continuation<T> {
+    override val context = EmptyCoroutineContext
+    override fun resumeWith(result: Result<T>) {
+        x(result.getOrThrow())
+    }
+}
+
+fun handleExceptionContinuation(x: (Throwable) -> Unit): Continuation<Any?> = object: Continuation<Any?> {
+    override val context = EmptyCoroutineContext
+    override fun resumeWith(result: Result<Any?>) {
+        result.exceptionOrNull()?.let(x)
+    }
+}
+
+open class EmptyContinuation(override val context: CoroutineContext = EmptyCoroutineContext) : Continuation<Any?> {
+    companion object : EmptyContinuation()
+    override fun resumeWith(result: Result<Any?>) {
+        result.getOrThrow()
+    }
+}
+
+class ResultContinuation : Continuation<Any?> {
+    override val context = EmptyCoroutineContext
+    override fun resumeWith(result: Result<Any?>) {
+        this.result = result.getOrThrow()
+    }
+
+    var result: Any? = null
+}
+
+abstract class ContinuationAdapter<in T> : Continuation<T> {
+    override val context: CoroutineContext = EmptyCoroutineContext
+    override fun resumeWith(result: Result<T>) {
+        if (result.isSuccess) {
+            resume(result.getOrThrow())
+        } else {
+            resumeWithException(result.exceptionOrNull()!!)
+        }
+    }
+
+    abstract fun resumeWithException(exception: Throwable)
+    abstract fun resume(value: T)
+}
diff --git a/compiler/testData/diagnostics/helpers/coroutines/StateMachineChecker.kt b/compiler/testData/diagnostics/helpers/coroutines/StateMachineChecker.kt
new file mode 100644
index 00000000000..69a47f6aac6
--- /dev/null
+++ b/compiler/testData/diagnostics/helpers/coroutines/StateMachineChecker.kt
@@ -0,0 +1,52 @@
+package helpers
+
+import kotlin.coroutines.*
+import kotlin.coroutines.intrinsics.*
+import kotlin.coroutines.jvm.internal.*
+
+class StateMachineCheckerClass {
+    private var counter = 0
+    var finished = false
+
+    var proceed: () -> Unit = {}
+
+    fun reset() {
+        counter = 0
+        finished = false
+        proceed = {}
+    }
+
+    suspend fun suspendHere() = suspendCoroutine<Unit> { c ->
+        counter++
+        proceed = { c.resume(Unit) }
+    }
+
+    fun check(numberOfSuspensions: Int, checkFinished: Boolean = true) {
+        for (i in 1..numberOfSuspensions) {
+            if (counter != i) error("Wrong state-machine generated: suspendHere should be called exactly once in one state. Expected " + i + ", got " + counter)
+            proceed()
+        }
+        if (counter != numberOfSuspensions)
+            error("Wrong state-machine generated: wrong number of overall suspensions. Expected " + numberOfSuspensions + ", got " + counter)
+        if (finished) error("Wrong state-machine generated: it is finished early")
+        proceed()
+        if (checkFinished && !finished) error("Wrong state-machine generated: it is not finished yet")
+    }
+}
+
+val StateMachineChecker = StateMachineCheckerClass()
+
+object CheckStateMachineContinuation: ContinuationAdapter<Unit>() {
+    override val context: CoroutineContext
+        get() = EmptyCoroutineContext
+
+    override fun resume(value: Unit) {
+        StateMachineChecker.proceed = {
+            StateMachineChecker.finished = true
+        }
+    }
+
+    override fun resumeWithException(exception: Throwable) {
+        throw exception
+    }
+}
diff --git a/compiler/testData/diagnostics/helpers/coroutines/TailCallOptimizationChecker.kt b/compiler/testData/diagnostics/helpers/coroutines/TailCallOptimizationChecker.kt
new file mode 100644
index 00000000000..ad89c2c337c
--- /dev/null
+++ b/compiler/testData/diagnostics/helpers/coroutines/TailCallOptimizationChecker.kt
@@ -0,0 +1,35 @@
+package helpers
+
+import kotlin.coroutines.*
+import kotlin.coroutines.intrinsics.*
+import kotlin.coroutines.jvm.internal.*
+
+class TailCallOptimizationCheckerClass {
+    private val stackTrace = arrayListOf<StackTraceElement?>()
+
+    suspend fun saveStackTrace() = suspendCoroutineUninterceptedOrReturn<Unit> {
+        saveStackTrace(it)
+    }
+
+    fun saveStackTrace(c: Continuation<*>) {
+        if (c !is CoroutineStackFrame) error("Continuation " + c + " is not subtype of CoroutineStackFrame")
+        stackTrace.clear()
+        var csf: CoroutineStackFrame? = c
+        while (csf != null) {
+            stackTrace.add(csf.getStackTraceElement())
+            csf = csf.callerFrame
+        }
+    }
+
+    fun checkNoStateMachineIn(method: String) {
+        stackTrace.find { it?.methodName?.startsWith(method) == true }?.let { error("tail-call optimization miss: method at " + it + " has state-machine " +
+                                                                                            stackTrace.joinToString(separator = "\n")) }
+    }
+
+    fun checkStateMachineIn(method: String) {
+        stackTrace.find { it?.methodName?.startsWith(method) == true } ?: error("tail-call optimization hit: method " + method + " has no state-machine " +
+                                                                                        stackTrace.joinToString(separator = "\n"))
+    }
+}
+
+val TailCallOptimizationChecker = TailCallOptimizationCheckerClass()