diff --git a/build.gradle.kts b/build.gradle.kts
index 1c4fae0ce..b6e9a7271 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -59,6 +59,9 @@ configure(
         implementation("org.slf4j:slf4j-api")
         implementation("com.github.multiformats:java-multibase:v1.1.1")
 
+        testFixturesImplementation("com.google.guava:guava")
+        testFixturesImplementation("org.slf4j:slf4j-api")
+
         testImplementation("org.junit.jupiter:junit-jupiter")
         testImplementation("org.junit.jupiter:junit-jupiter-params")
         testImplementation("io.mockk:mockk")
diff --git a/libp2p/build.gradle.kts b/libp2p/build.gradle.kts
index 89c85a2d8..4012cb2d7 100644
--- a/libp2p/build.gradle.kts
+++ b/libp2p/build.gradle.kts
@@ -19,9 +19,12 @@ dependencies {
     implementation("org.bouncycastle:bcpkix-jdk15on")
 
     testImplementation(project(":tools:schedulers"))
-    testImplementation("org.apache.logging.log4j:log4j-core")
 
+    testFixturesApi("org.apache.logging.log4j:log4j-core")
+    testFixturesImplementation(project(":tools:schedulers"))
     testFixturesImplementation("io.netty:netty-transport-classes-epoll")
+    testFixturesImplementation("io.netty:netty-handler")
+    testFixturesImplementation("org.junit.jupiter:junit-jupiter-api")
 
     jmhImplementation(project(":tools:schedulers"))
     jmhImplementation("org.openjdk.jmh:jmh-core")
diff --git a/libp2p/src/main/kotlin/io/libp2p/mux/mplex/MplexFrame.kt b/libp2p/src/main/kotlin/io/libp2p/mux/mplex/MplexFrame.kt
index 13868402d..fb4e11bc0 100644
--- a/libp2p/src/main/kotlin/io/libp2p/mux/mplex/MplexFrame.kt
+++ b/libp2p/src/main/kotlin/io/libp2p/mux/mplex/MplexFrame.kt
@@ -14,6 +14,7 @@ package io.libp2p.mux.mplex
 
 import io.libp2p.etc.util.netty.mux.MuxId
 import io.netty.buffer.ByteBuf
+import io.netty.buffer.DefaultByteBufHolder
 import io.netty.buffer.Unpooled
 
 /**
@@ -24,7 +25,7 @@ import io.netty.buffer.Unpooled
  * @param data the data segment.
  * @see [mplex documentation](https://github.com/libp2p/specs/tree/master/mplex#opening-a-new-stream)
  */
-data class MplexFrame(val id: MuxId, val flag: MplexFlag, val data: ByteBuf) {
+data class MplexFrame(val id: MuxId, val flag: MplexFlag, val data: ByteBuf) : DefaultByteBufHolder(data) {
 
     companion object {
         fun createDataFrame(id: MuxId, data: ByteBuf) =
diff --git a/libp2p/src/test/kotlin/io/libp2p/mux/mplex/MplexFrameCodecTest.kt b/libp2p/src/test/kotlin/io/libp2p/mux/mplex/MplexFrameCodecTest.kt
index 8139f61df..6ba816250 100644
--- a/libp2p/src/test/kotlin/io/libp2p/mux/mplex/MplexFrameCodecTest.kt
+++ b/libp2p/src/test/kotlin/io/libp2p/mux/mplex/MplexFrameCodecTest.kt
@@ -30,20 +30,20 @@ class MplexFrameCodecTest {
         )
     }
     val dummyId = DefaultChannelId.newInstance()
+    val maxFrameDataLength = 1024
+    val channel = EmbeddedChannel(MplexFrameCodec(maxFrameDataLength = maxFrameDataLength))
 
     @Test
     fun `check max frame size limit`() {
-        val channelLarge = EmbeddedChannel(MplexFrameCodec(maxFrameDataLength = 1024))
-
         val mplexFrame = MplexFrame(
             MuxId(dummyId, 777, true), MplexFlag.MessageInitiator,
-            ByteArray(1024).toByteBuf()
+            ByteArray(maxFrameDataLength).toByteBuf()
         )
 
         assertTrue(
-            channelLarge.writeOutbound(mplexFrame)
+            channel.writeOutbound(mplexFrame)
         )
-        val largeFrameBytes = channelLarge.readOutbound<ByteBuf>()
+        val largeFrameBytes = channel.readOutbound<ByteBuf>()
         val largeFrameBytesTrunc = largeFrameBytes.slice(0, largeFrameBytes.readableBytes() - 1)
 
         val channelSmall = EmbeddedChannel(MplexFrameCodec(maxFrameDataLength = 128))
@@ -58,8 +58,6 @@ class MplexFrameCodecTest {
     @ParameterizedTest
     @MethodSource("splitIndexes")
     fun testDecoder(sliceIdx: List<Int>) {
-        val channel = EmbeddedChannel(MplexFrameCodec())
-
         val mplexFrames = arrayOf(
             MplexFrame(MuxId(dummyId, 777, true), MplexFlag.MessageInitiator, "Hello-1".toByteArray().toByteBuf()),
             MplexFrame(MuxId(dummyId, 888, true), MplexFlag.MessageInitiator, "Hello-2".toByteArray().toByteBuf()),
@@ -93,8 +91,6 @@ class MplexFrameCodecTest {
 
     @Test
     fun `test id initiator is inverted on decoding`() {
-        val channel = EmbeddedChannel(MplexFrameCodec())
-
         val mplexFrames = arrayOf(
             MplexFrame.createOpenFrame(MuxId(dummyId, 1, true)),
             MplexFrame.createDataFrame(MuxId(dummyId, 2, true), "Hello-2".toByteArray().toByteBuf()),
@@ -118,4 +114,21 @@ class MplexFrameCodecTest {
             assertEquals(mplexFrames[idx].flag, resFrame.flag)
         }
     }
+
+    @Test
+    fun `check the frame underlying buffer is released after send`() {
+        val frameDataBuf = "Hello-1".toByteArray().toByteBuf()
+
+        assertTrue(frameDataBuf.refCnt() == 1)
+
+        channel.writeOutbound(
+            MplexFrame(MuxId(dummyId, 777, true), MplexFlag.MessageInitiator, frameDataBuf)
+        )
+
+        val encodedFrame = channel.readOutbound<ByteBuf>()
+        // bytes are released after sending to the wire
+        encodedFrame.release()
+
+        assertTrue(frameDataBuf.refCnt() == 0)
+    }
 }
diff --git a/libp2p/src/test/kotlin/io/libp2p/pubsub/DeterministicFuzz.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/pubsub/DeterministicFuzz.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/pubsub/DeterministicFuzz.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/pubsub/DeterministicFuzz.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/pubsub/MockRouter.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/pubsub/MockRouter.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/pubsub/MockRouter.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/pubsub/MockRouter.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/pubsub/TestRouter.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/pubsub/TestRouter.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/pubsub/TestRouter.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/pubsub/TestRouter.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/pubsub/gossip/Eth2GossipParams.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/pubsub/gossip/Eth2GossipParams.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/pubsub/gossip/Eth2GossipParams.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/pubsub/gossip/Eth2GossipParams.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/CountingPingProtocol.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/CountingPingProtocol.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/CountingPingProtocol.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/CountingPingProtocol.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/DnsAvailability.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/DnsAvailability.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/DnsAvailability.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/DnsAvailability.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/DoNothingProtocol.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/DoNothingProtocol.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/DoNothingProtocol.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/DoNothingProtocol.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/EchoProtocol.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/EchoProtocol.kt
similarity index 97%
rename from libp2p/src/test/kotlin/io/libp2p/tools/EchoProtocol.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/EchoProtocol.kt
index 4da4b6581..17b14dda4 100644
--- a/libp2p/src/test/kotlin/io/libp2p/tools/EchoProtocol.kt
+++ b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/EchoProtocol.kt
@@ -44,7 +44,8 @@ open class EchoProtocol : ProtocolHandler<EchoController>(Long.MAX_VALUE, Long.M
         }
     }
 
-    open inner class EchoInitiator(val ready: CompletableFuture<Void>) : ProtocolMessageHandler<ByteBuf>, EchoController {
+    open inner class EchoInitiator(val ready: CompletableFuture<Void>) :
+        ProtocolMessageHandler<ByteBuf>, EchoController {
         lateinit var stream: Stream
         var ret = CompletableFuture<String>()
 
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/HostFactory.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/HostFactory.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/HostFactory.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/HostFactory.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/NullHost.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/NullHost.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/NullHost.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/NullHost.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/NullTransport.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/NullTransport.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/NullTransport.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/NullTransport.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/P2pdRunner.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/P2pdRunner.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/P2pdRunner.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/P2pdRunner.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/Stubs.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/Stubs.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/Stubs.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/Stubs.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/TCPProxy.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/TCPProxy.kt
similarity index 97%
rename from libp2p/src/test/kotlin/io/libp2p/tools/TCPProxy.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/TCPProxy.kt
index 6c3de7390..3f4ad2346 100644
--- a/libp2p/src/test/kotlin/io/libp2p/tools/TCPProxy.kt
+++ b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/TCPProxy.kt
@@ -12,8 +12,6 @@ import io.netty.channel.socket.nio.NioServerSocketChannel
 import io.netty.channel.socket.nio.NioSocketChannel
 import io.netty.handler.logging.LogLevel
 import io.netty.handler.logging.LoggingHandler
-import org.junit.jupiter.api.Disabled
-import org.junit.jupiter.api.Test
 import java.util.concurrent.CompletableFuture
 
 // Utility class (aka sniffer) that just forwards TCP traffic back'n'forth to another TCP address and log it
@@ -67,8 +65,6 @@ class TCPProxy {
         return future
     }
 
-    @Test
-    @Disabled
     fun run() {
         start(11111, "localhost", 10000)
             .channel().closeFuture().await()
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/TestChannel.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/TestChannel.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/TestChannel.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/TestChannel.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/TestHandler.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/TestHandler.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/TestHandler.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/TestHandler.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/TestLogAppender.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/TestLogAppender.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/TestLogAppender.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/TestLogAppender.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/TestStreamChannel.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/TestStreamChannel.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/TestStreamChannel.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/TestStreamChannel.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/protobuf/ProtobufUtils.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/protobuf/ProtobufUtils.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/protobuf/ProtobufUtils.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/protobuf/ProtobufUtils.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/tools/protobuf/RpcBuilder.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/tools/protobuf/RpcBuilder.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/tools/protobuf/RpcBuilder.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/tools/protobuf/RpcBuilder.kt
diff --git a/libp2p/src/test/kotlin/io/libp2p/transport/NullConnectionUpgrader.kt b/libp2p/src/testFixtures/kotlin/io/libp2p/transport/NullConnectionUpgrader.kt
similarity index 100%
rename from libp2p/src/test/kotlin/io/libp2p/transport/NullConnectionUpgrader.kt
rename to libp2p/src/testFixtures/kotlin/io/libp2p/transport/NullConnectionUpgrader.kt