[wip] stub in the "upload_download" Codex Testground plan

testground/upload_download/Dockerfile

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+FROM nimbase
+
+COPY . .
+
+RUN cd /extra/scratch/nim-codex && \
+    make USE_SYSTEM_NIM=1 update
+
+RUN cd /extra/scratch/nim-codex && \
+    make USE_SYSTEM_NIM=1 TESTGROUND_PLAN=upload_download testground_exec
+
+ENTRYPOINT ["/extra/scratch/nim-codex/build/codex_testground"]

testground/upload_download/config.nims

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+switch("define", "chronicles_sinks=textlines")
+switch("define", "chronicles_log_level=NOTICE")

testground/upload_download/main.nim

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+import std/strutils
+
+import pkg/chronos
+import pkg/stew/byteutils
+import pkg/testground_sdk
+
+testground(client):
+  let
+    myId = await client.signalAndWait("setup", client.testInstanceCount)
+    myIp = client.testSubnet.split('.')[0..1].join(".") & ".1." & $myId
+    serverIp = client.testSubnet.split('.')[0..1].join(".") & ".1.1"
+
+  await client.updateNetworkParameter(
+    NetworkConf(
+      network: "default",
+      ipv4: some myIp & "/24",
+      enable: true,
+      callback_state: "network_setup",
+      callback_target: some client.testInstanceCount,
+      routing_policy: "accept_all",
+    )
+  )
+
+  await client.waitForBarrier("network_setup", client.testInstanceCount)
+
+  let
+    payload = client.param(string, "payload")
+    count = client.param(int, "count")
+    printResult = client.param(bool, "printResult")
+
+  if myId == 1: # server
+    let
+      server = createStreamServer(
+        initTAddress(myIp & ":5050"), flags = {ReuseAddr})
+
+      connection = await server.accept()
+
+    for _ in 0 ..< count:
+      doAssert (await connection.write(payload.toBytes())) == payload.len
+
+    connection.close()
+
+  else: # client
+    let
+      connection = await connect(initTAddress(serverIp & ":5050"))
+
+    var
+      buffer = newSeq[byte](payload.len)
+
+    for _ in 0 ..< count:
+      await connection.readExactly(addr buffer[0], payload.len)
+      doAssert string.fromBytes(buffer) == payload
+
+    connection.close()
+
+  if printResult:
+    client.recordMessage("Hourray " & $myId & "!")

testground/upload_download/manifest.toml

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+name = "upload_download"
+
+[defaults]
+builder = "docker:generic"
+runner = "local:docker"
+
+[builders."docker:generic"]
+enabled = true
+
+[runners."local:docker"]
+enabled = true
+
+[[testcases]]
+name= "default"
+instances = { min = 2, default = 2, max = 2 }
+
+[testcases.params]
+payload = { type = "string", default = "Hello!" }
+count = { type = "int", default = 2 }
+printResult = { type = "bool", default = true }
+
+[extra_sources]
+  docker_generic = [
+    "../../scratch"
+  ]