problem: some nodes may respond with a JSON RPC setting a non-200 status code but Dshackle ignores that JSON

src/test/groovy/io/emeraldpay/dshackle/upstream/rpcclient/JsonRpcHttpClientSpec.groovy

@@ -26,6 +26,7 @@ import org.mockserver.model.HttpRequest
 import org.mockserver.model.HttpResponse
 import org.mockserver.model.MediaType
 import org.springframework.util.SocketUtils
+import reactor.core.Exceptions
 import reactor.test.StepVerifier
 import spock.lang.Specification
 
@@ -84,7 +85,7 @@ class JsonRpcHttpClientSpec extends Specification {
                         .withBody("pong")
         )
         when:
-        def act = client.execute("ping".bytes).map { new String(it) }
+        def act = client.execute("ping".bytes).map { new String(it.t2) }
         then:
         StepVerifier.create(act)
                 .expectNext("pong")
@@ -111,13 +112,44 @@ class JsonRpcHttpClientSpec extends Specification {
                         .withBody("pong")
         )
         when:
-        def act = client.execute("ping".bytes).map { new String(it) }
+        def act = client.read(
+                new JsonRpcRequest("ping", [])
+        ).block(Duration.ofSeconds(1))
         then:
-        StepVerifier.create(act)
-                .expectErrorMatches { t ->
-                    t instanceof JsonRpcException && t.error.code == RpcResponseError.CODE_UPSTREAM_INVALID_RESPONSE
-                }
-                .verify(Duration.ofSeconds(1))
+        def t = thrown(RuntimeException) // reactor.core.Exceptions$ReactiveException
+        t.cause instanceof JsonRpcException
+        with(((JsonRpcException)t.cause).error) {
+            code == RpcResponseError.CODE_UPSTREAM_INVALID_RESPONSE
+            message == "HTTP Code: 500"
+        }
+    }
+
+    def "Tries to extract message if HTTP error if it still contains a JSON RPC message"() {
+        setup:
+        def client = new JsonRpcHttpClient("localhost:${port}", metrics, null, null)
+
+        mockServer.when(
+                HttpRequest.request()
+        ).respond(
+                HttpResponse.response()
+                        .withStatusCode(500)
+                        .withBody('{' +
+                                '"jsonrpc": "2.0", ' +
+                                '"id": 1, ' +
+                                '"error": {"code": -32603, "message": "Something happened"}' +
+                                '}')
+        )
+        when:
+        def act = client.read(
+                new JsonRpcRequest("ping", [])
+        ).block(Duration.ofSeconds(1))
+        then:
+        def t = thrown(RuntimeException) // reactor.core.Exceptions$ReactiveException
+        t.cause instanceof JsonRpcException
+        with(((JsonRpcException)t.cause).error) {
+            code == -32603
+            message == "Something happened"
+        }
     }
 
 }