diff --git a/kotlinx-coroutines-core/api/kotlinx-coroutines-core.api b/kotlinx-coroutines-core/api/kotlinx-coroutines-core.api
index 546bfe3507..7f99a31afd 100644
--- a/kotlinx-coroutines-core/api/kotlinx-coroutines-core.api
+++ b/kotlinx-coroutines-core/api/kotlinx-coroutines-core.api
@@ -545,6 +545,15 @@ public final class kotlinx/coroutines/TimeoutKt {
 	public static final fun withTimeoutOrNull-KLykuaI (JLkotlin/jvm/functions/Function2;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 }
 
+public final class kotlinx/coroutines/YieldContext : kotlin/coroutines/AbstractCoroutineContextElement {
+	public static final field Key Lkotlinx/coroutines/YieldContext$Key;
+	public field dispatcherWasUnconfined Z
+	public fun <init> ()V
+}
+
+public final class kotlinx/coroutines/YieldContext$Key : kotlin/coroutines/CoroutineContext$Key {
+}
+
 public final class kotlinx/coroutines/YieldKt {
 	public static final fun yield (Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 }
diff --git a/kotlinx-coroutines-core/common/src/Unconfined.kt b/kotlinx-coroutines-core/common/src/Unconfined.kt
index 24a401f702..5837ae83f3 100644
--- a/kotlinx-coroutines-core/common/src/Unconfined.kt
+++ b/kotlinx-coroutines-core/common/src/Unconfined.kt
@@ -38,6 +38,7 @@ internal object Unconfined : CoroutineDispatcher() {
 /**
  * Used to detect calls to [Unconfined.dispatch] from [yield] function.
  */
+@PublishedApi
 internal class YieldContext : AbstractCoroutineContextElement(Key) {
     companion object Key : CoroutineContext.Key<YieldContext>
 
diff --git a/kotlinx-coroutines-test/api/kotlinx-coroutines-test.api b/kotlinx-coroutines-test/api/kotlinx-coroutines-test.api
index 15d894e18d..f024f2105f 100644
--- a/kotlinx-coroutines-test/api/kotlinx-coroutines-test.api
+++ b/kotlinx-coroutines-test/api/kotlinx-coroutines-test.api
@@ -9,15 +9,6 @@ public abstract interface class kotlinx/coroutines/test/DelayController {
 	public abstract fun runCurrent ()V
 }
 
-public final class kotlinx/coroutines/test/StandardTestDispatcher : kotlinx/coroutines/test/TestDispatcher, kotlinx/coroutines/Delay {
-	public fun <init> ()V
-	public fun <init> (Lkotlinx/coroutines/test/TestCoroutineScheduler;Ljava/lang/String;)V
-	public synthetic fun <init> (Lkotlinx/coroutines/test/TestCoroutineScheduler;Ljava/lang/String;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
-	public fun dispatch (Lkotlin/coroutines/CoroutineContext;Ljava/lang/Runnable;)V
-	public fun getScheduler ()Lkotlinx/coroutines/test/TestCoroutineScheduler;
-	public fun toString ()Ljava/lang/String;
-}
-
 public final class kotlinx/coroutines/test/TestBuildersKt {
 	public static final fun runBlockingTest (Lkotlin/coroutines/CoroutineContext;Lkotlin/jvm/functions/Function2;)V
 	public static final fun runBlockingTest (Lkotlinx/coroutines/test/TestCoroutineDispatcher;Lkotlin/jvm/functions/Function2;)V
@@ -49,6 +40,13 @@ public final class kotlinx/coroutines/test/TestCoroutineDispatcher : kotlinx/cor
 	public fun toString ()Ljava/lang/String;
 }
 
+public final class kotlinx/coroutines/test/TestCoroutineDispatchersKt {
+	public static final fun StandardTestDispatcher (Lkotlinx/coroutines/test/TestCoroutineScheduler;Ljava/lang/String;)Lkotlinx/coroutines/test/TestDispatcher;
+	public static synthetic fun StandardTestDispatcher$default (Lkotlinx/coroutines/test/TestCoroutineScheduler;Ljava/lang/String;ILjava/lang/Object;)Lkotlinx/coroutines/test/TestDispatcher;
+	public static final fun UnconfinedTestDispatcher (Lkotlinx/coroutines/test/TestCoroutineScheduler;Ljava/lang/String;)Lkotlinx/coroutines/test/TestDispatcher;
+	public static synthetic fun UnconfinedTestDispatcher$default (Lkotlinx/coroutines/test/TestCoroutineScheduler;Ljava/lang/String;ILjava/lang/Object;)Lkotlinx/coroutines/test/TestDispatcher;
+}
+
 public final class kotlinx/coroutines/test/TestCoroutineExceptionHandler : kotlin/coroutines/AbstractCoroutineContextElement, kotlinx/coroutines/CoroutineExceptionHandler, kotlinx/coroutines/test/UncaughtExceptionCaptor {
 	public fun <init> ()V
 	public fun cleanupTestCoroutinesCaptor ()V
@@ -88,7 +86,6 @@ public final class kotlinx/coroutines/test/TestCoroutineScopeKt {
 }
 
 public abstract class kotlinx/coroutines/test/TestDispatcher : kotlinx/coroutines/CoroutineDispatcher, kotlinx/coroutines/Delay {
-	public fun <init> ()V
 	public fun delay (JLkotlin/coroutines/Continuation;)Ljava/lang/Object;
 	public abstract fun getScheduler ()Lkotlinx/coroutines/test/TestCoroutineScheduler;
 	public fun invokeOnTimeout (JLjava/lang/Runnable;Lkotlin/coroutines/CoroutineContext;)Lkotlinx/coroutines/DisposableHandle;
@@ -105,13 +102,3 @@ public abstract interface class kotlinx/coroutines/test/UncaughtExceptionCaptor
 	public abstract fun getUncaughtExceptions ()Ljava/util/List;
 }
 
-public final class kotlinx/coroutines/test/UnconfinedTestDispatcher : kotlinx/coroutines/test/TestDispatcher, kotlinx/coroutines/Delay {
-	public fun <init> ()V
-	public fun <init> (Lkotlinx/coroutines/test/TestCoroutineScheduler;Ljava/lang/String;)V
-	public synthetic fun <init> (Lkotlinx/coroutines/test/TestCoroutineScheduler;Ljava/lang/String;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
-	public fun dispatch (Lkotlin/coroutines/CoroutineContext;Ljava/lang/Runnable;)V
-	public fun getScheduler ()Lkotlinx/coroutines/test/TestCoroutineScheduler;
-	public fun isDispatchNeeded (Lkotlin/coroutines/CoroutineContext;)Z
-	public fun toString ()Ljava/lang/String;
-}
-
diff --git a/kotlinx-coroutines-test/common/src/TestCoroutineDispatcher.kt b/kotlinx-coroutines-test/common/src/TestCoroutineDispatcher.kt
index 32fe1829d3..31249ee6e4 100644
--- a/kotlinx-coroutines-test/common/src/TestCoroutineDispatcher.kt
+++ b/kotlinx-coroutines-test/common/src/TestCoroutineDispatcher.kt
@@ -36,12 +36,6 @@ public class TestCoroutineDispatcher(public override val scheduler: TestCoroutin
             }
         }
 
-    /** @suppress */
-    override fun processEvent(time: Long, marker: Any) {
-        check(marker is Runnable)
-        marker.run()
-    }
-
     /** @suppress */
     override fun dispatch(context: CoroutineContext, block: Runnable) {
         checkSchedulerInContext(scheduler, context)
diff --git a/kotlinx-coroutines-test/common/src/TestCoroutineDispatchers.kt b/kotlinx-coroutines-test/common/src/TestCoroutineDispatchers.kt
index 7f3faf0211..bd04c046e7 100644
--- a/kotlinx-coroutines-test/common/src/TestCoroutineDispatchers.kt
+++ b/kotlinx-coroutines-test/common/src/TestCoroutineDispatchers.kt
@@ -29,21 +29,19 @@ import kotlin.coroutines.*
  * scheduler in order for the tasks to run.
  */
 @ExperimentalCoroutinesApi
-public class UnconfinedTestDispatcher(
-    public override val scheduler: TestCoroutineScheduler = TestCoroutineScheduler(),
-    private val name: String? = null
-): TestDispatcher(), Delay {
+@Suppress("FunctionName")
+public fun UnconfinedTestDispatcher(
+    scheduler: TestCoroutineScheduler = TestCoroutineScheduler(),
+    name: String? = null
+): TestDispatcher = UnconfinedTestDispatcherImpl(scheduler, name)
 
-    /** @suppress */
-    override fun processEvent(time: Long, marker: Any) {
-        check(marker is Runnable)
-        marker.run()
-    }
+private class UnconfinedTestDispatcherImpl(
+    override val scheduler: TestCoroutineScheduler,
+    private val name: String? = null
+): TestDispatcher() {
 
-    /** @suppress */
     override fun isDispatchNeeded(context: CoroutineContext): Boolean = false
 
-    /** @suppress */
     @Suppress("INVISIBLE_MEMBER")
     override fun dispatch(context: CoroutineContext, block: Runnable) {
         checkSchedulerInContext(scheduler, context)
@@ -64,9 +62,7 @@ public class UnconfinedTestDispatcher(
         )
     }
 
-    /** @suppress */
     override fun toString(): String = "${name ?: "UnconfinedTestDispatcher"}[scheduler=$scheduler]"
-
 }
 
 /**
@@ -88,26 +84,22 @@ public class UnconfinedTestDispatcher(
  *
  * @see UnconfinedTestDispatcher for a dispatcher that is not confined to any particular thread.
  */
+@Suppress("FunctionName")
+public fun StandardTestDispatcher(
+    scheduler: TestCoroutineScheduler = TestCoroutineScheduler(),
+    name: String? = null
+): TestDispatcher = StandardTestDispatcherImpl(scheduler, name)
+
 @ExperimentalCoroutinesApi
-public class StandardTestDispatcher(
-    public override val scheduler: TestCoroutineScheduler = TestCoroutineScheduler(),
+private class StandardTestDispatcherImpl(
+    override val scheduler: TestCoroutineScheduler = TestCoroutineScheduler(),
     private val name: String? = null
-): TestDispatcher(), Delay {
+): TestDispatcher() {
 
-    /** @suppress */
-    override fun processEvent(time: Long, marker: Any) {
-        check(marker is Runnable)
-        marker.run()
-    }
-
-    /** @suppress */
-    @Suppress("INVISIBLE_MEMBER")
     override fun dispatch(context: CoroutineContext, block: Runnable) {
         checkSchedulerInContext(scheduler, context)
         scheduler.registerEvent(this, 0, block) { false }
     }
 
-    /** @suppress */
-    override fun toString(): String = "${name ?: "ConfinedTestDispatcher"}[scheduler=$scheduler]"
-
+    override fun toString(): String = "${name ?: "StandardTestDispatcher"}[scheduler=$scheduler]"
 }
diff --git a/kotlinx-coroutines-test/common/src/TestDispatcher.kt b/kotlinx-coroutines-test/common/src/TestDispatcher.kt
index b37f10bfda..2ad34d90bd 100644
--- a/kotlinx-coroutines-test/common/src/TestDispatcher.kt
+++ b/kotlinx-coroutines-test/common/src/TestDispatcher.kt
@@ -12,13 +12,16 @@ import kotlin.jvm.*
  * A test dispatcher that can interface with a [TestCoroutineScheduler].
  */
 @ExperimentalCoroutinesApi
-public abstract class TestDispatcher: CoroutineDispatcher(), Delay {
+public sealed class TestDispatcher: CoroutineDispatcher(), Delay {
     /** The scheduler that this dispatcher is linked to. */
     @ExperimentalCoroutinesApi
     public abstract val scheduler: TestCoroutineScheduler
 
     /** Notifies the dispatcher that it should process a single event marked with [marker] happening at time [time]. */
-    internal abstract fun processEvent(time: Long, marker: Any)
+    internal open fun processEvent(time: Long, marker: Any) {
+        check(marker is Runnable)
+        marker.run()
+    }
 
     /** @suppress */
     override fun scheduleResumeAfterDelay(timeMillis: Long, continuation: CancellableContinuation<Unit>) {