ZIO client streaming transport and generic tests (#148)

* feat: split client into regular and bidirectional one depending on transport

# Conflicts:
#	client/src/main/scala/chimp/client/McpClientImpl.scala
#	client/src/main/scala/chimp/client/transport/HttpTransport.scala

* feat: effectful client creation, initialize internally, avoids having  transient client state

* refactor: small refactor

* refactor: more readable response handling in http transport

* feat: zio client parts

* refactor: rename

* refactor: logging

* refactor: logging

* feat: integration tests WIP

* feat: integration tests WIP

* feat: integration tests WIP

* fix: flush chunks eagerly for ZIO stdio transport

* feat: add integration tests to ci

* fix: merge error

* feat: extend integration tests WIP

* fix: fix resource type tool tests

* fix: formatting

* refactor: abstract test cases over mcp client only instead over transport

* feat: default, scoped and layered factory methods for zio transport to match sttp

* fix: fix zio stdio transport hung on close

* fix: remove streams evidence from streaming stdio transport, it makes sense only to narrow down possible sttp http backend choices

* review: resolve critical findings

* feat: configurable timeout of async zio transport

* feat: require resumability for SSE stream from streaming http transports, implement for ZIO and generic test using toxiproxy

* review: avoid Thread.sleep(), abstract sleep to implement for effects

* wip: few more test cases for server sens events and client responses

* wip: few more test cases for server sens events and client responses

* fix: fix restarting SSE listener on transport close by introducing closing flag

* fix: take closing ref into account when resuming stream for pending request too

* fix: define retry policy for SSE stream reconnect instead of fixed delay

* fix: improve shutdown, make pending requests truly internal

* fix: move -32000 error to enum

* fix: specific version of everything container and latest toxiproxy

Author: kubinio123

.github/workflows/ci.yml

@@ -44,12 +44,14 @@ jobs:
         # TODO bring this step back after first release with new project structure (client + server)
 #      - name: Verify that examples compile using Scala CLI
 #        run: sbt -v "project examples" verifyExamplesCompileUsingScalaCli
-      - name: Test
+      - name: Unit tests
         run: sbt -v test
-      - name: Client conformance
+      - name: Client conformance tests
         run: sbt -v "clientConformance/conformance client --suite core"
-      - name: Server conformance
+      - name: Server conformance tests
         run: sbt -v "serverConformance/conformance server"
+      - name: Integration tests
+        run: sbt -v "testOnly -- -n Integration"
       - uses: actions/upload-artifact@v5  # upload test results
         if: success() || failure()        # run this step even if previous step failed
         with:

build.sbt

@@ -8,6 +8,9 @@ val slf4jV = "2.0.18"
 val logbackV = "1.5.32"
 val tapirV = "1.13.19"
 val sttpClientV = "4.0.24"
+val zioV = "2.1.26"
+val zioProcessV = "0.8.0"
+val testcontainersScalaV = "0.41.8"
 
 lazy val verifyExamplesCompileUsingScalaCli = taskKey[Unit]("Verify that each example compiles using Scala CLI")
 
@@ -22,6 +25,8 @@ lazy val commonSettings = commonSmlBuildSettings ++ ossPublishSettings ++ Seq(
   }.value,
   Test / scalacOptions += "-Wconf:msg=unused value of type org.scalatest.Assertion:s",
   Test / scalacOptions += "-Wconf:msg=unused value of type org.scalatest.compatible.Assertion:s",
+  Test / test / testOptions += Tests.Argument(TestFrameworks.ScalaTest, "-l", "Integration"),
+  Test / parallelExecution := false,
   scalacOptions ++= Seq("-Wunused:all", "-Werror")
 )
 
@@ -30,7 +35,7 @@ val scalaTest = "org.scalatest" %% "scalatest" % scalaTestV % Test
 lazy val root = (project in file("."))
   .settings(commonSettings: _*)
   .settings(publishArtifact := false, name := "chimp")
-  .aggregate(core, server, client, examples, serverConformance, clientConformance)
+  .aggregate(core, server, client, clientZio, examples, serverConformance, clientConformance)
 
 val conformance = inputKey[Unit]("Run the MCP conformance harness via npx, extra args are passed through")
 
@@ -68,18 +73,35 @@ lazy val client: Project = (project in file("client"))
     name := "chimp-client",
     libraryDependencies ++= Seq(
       scalaTest,
-      "com.softwaremill.sttp.client4" %% "core" % sttpClientV
+      "com.softwaremill.sttp.client4" %% "core" % sttpClientV,
+      "com.dimafeng" %% "testcontainers-scala-scalatest" % testcontainersScalaV % Test,
+      "ch.qos.logback" % "logback-classic" % logbackV % Test,
+      "com.dimafeng" %% "testcontainers-scala-toxiproxy" % testcontainersScalaV % Test
     )
   )
   .dependsOn(core)
 
+lazy val clientZio: Project = (project in file("client-streaming/client-zio"))
+  .settings(commonSettings: _*)
+  .settings(
+    name := "chimp-client-zio",
+    libraryDependencies ++= Seq(
+      scalaTest,
+      "dev.zio" %% "zio" % zioV,
+      "dev.zio" %% "zio-streams" % zioV,
+      "dev.zio" %% "zio-process" % zioProcessV,
+      "com.softwaremill.sttp.client4" %% "zio" % sttpClientV
+    )
+  )
+  .dependsOn(client % "compile->compile;test->test")
+
 lazy val examples = (project in file("examples"))
   .settings(commonSettings: _*)
   .settings(
     publishArtifact := false,
     name := "examples",
     libraryDependencies ++= Seq(
-      "com.softwaremill.sttp.client4" %% "core" % "4.0.24",
+      "com.softwaremill.sttp.client4" %% "core" % sttpClientV,
       "com.softwaremill.sttp.tapir" %% "tapir-netty-server-sync" % tapirV,
       "com.softwaremill.sttp.tapir" %% "tapir-zio-http-server" % tapirV,
       "ch.qos.logback" % "logback-classic" % logbackV

client-conformance/src/main/scala/chimp/conformance/client/Main.scala

@@ -34,14 +34,12 @@ object Main:
       try
         scenario match
           case "initialize" =>
-            val client = McpClient[Identity](transport, clientInfo, protocolVersion = protocolVersion)
-            val _ = client.initialize()
+            val client = McpClient[Identity](transport, clientInfo, protocolVersion)
             client.close()
             0
 
           case "tools_call" =>
-            val client = McpClient[Identity](transport, clientInfo, protocolVersion = protocolVersion)
-            val _ = client.initialize()
+            val client = McpClient[Identity](transport, clientInfo, protocolVersion)
             val _ = client.callTool(
               "add_numbers",
               Json.obj("a" -> Json.fromInt(2), "b" -> Json.fromInt(3))