solution: integration test with two upstreams

testing/simple-upstream/src/main/groovy/testing/InternalHandler.groovy

@@ -0,0 +1,35 @@
+package testing
+
+import java.time.Instant
+import java.util.concurrent.atomic.AtomicInteger
+
+class InternalHandler implements CallHandler {
+
+    private AtomicInteger ids = new AtomicInteger()
+    private List<Item> requests = new ArrayList()
+
+    def record(String json) {
+        requests << new Item(ids.getAndIncrement(), json)
+    }
+
+    @Override
+    Result handle(String method, List<Object> params) {
+        if (method == "eth_call"
+                && params[0].to?.toLowerCase() == "0x0123456789abcdef0123456789abcdef00000002".toLowerCase()) {
+            return Result.ok(Collections.unmodifiableList(requests))
+        }
+        return null
+    }
+
+    class Item {
+        Integer id
+        String timestamp
+        String json
+
+        Item(Integer id, String json) {
+            this.id = id
+            this.timestamp = Instant.now().toString()
+            this.json = json
+        }
+    }
+}

testing/simple-upstream/src/main/groovy/testing/PingPongHandler.groovy

@@ -0,0 +1,12 @@
+package testing
+
+class PingPongHandler implements CallHandler {
+    @Override
+    Result handle(String method, List<Object> params) {
+        if (method == "eth_call"
+                && params[0].to?.toLowerCase() == "0x0123456789abcdef0123456789abcdef00000001".toLowerCase()) {
+            return Result.ok([data: params[0].data])
+        }
+        return null
+    }
+}

testing/simple-upstream/src/main/groovy/testing/SimpleUpstream.groovy

@@ -5,17 +5,23 @@ import spark.Spark
 
 class SimpleUpstream {
 
-    private int port = 18545
+    private int port = System.getenv("DSHACKLE_TESTUP_PORT")?.toInteger() ?: 18545
     private ObjectMapper objectMapper
 
     private List<CallHandler> handlers = []
+    private InternalHandler internalHandler
 
     void prepare() {
         objectMapper = new ObjectMapper()
 
+        internalHandler = new InternalHandler()
+
         handlers << new TestcaseHandler(objectMapper)
         handlers << new CommonHandlers()
         handlers << new BlocksHandler(objectMapper)
+        handlers << new PingPongHandler()
+        handlers << internalHandler
+
         handlers << new InvalidCallHandler()
     }
 
@@ -23,9 +29,11 @@ class SimpleUpstream {
         println("Starting upstream on 0.0.0.0:$port")
         Spark.port(port)
         Spark.post("/") { req, resp ->
-            println("request")
             try {
-                Map json = objectMapper.readValue(req.body(), Map)
+                def requestBody = req.body()
+                println("request: $requestBody")
+                internalHandler.record(requestBody)
+                Map json = objectMapper.readValue(requestBody, Map)
                 def id = json["id"]
                 String method = json["method"].toString()
                 List<Object> params = json.containsKey("params") ? json["params"] as List<Object> : []