problem: doesn't handle upstream error for additionally allowed methods; allowing an existing method redefines its logic

rel: #67

testing/dshackle/dshackle.yaml

@@ -11,6 +11,7 @@ cluster:
       methods:
         enabled:
           - name: debug_traceTransaction
+          - name: test_foo
       options:
         disable-validation: true
       connection:

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

@@ -34,6 +34,11 @@ class TestcaseHandler implements CallHandler {
                 && params[0].to?.toLowerCase() == "0xdAC17F958D2ee523a2206206994597C13D831ec7".toLowerCase()) {
             return Result.error(-32000, "invalid opcode: opcode 0xfe not defined")
         }
+        // https://github.com/emeraldpay/dshackle/issues/67, when a custom method configured
+        if (method == "test_foo"
+                && params[0].to?.toLowerCase() == "0xdAC17F958D2ee523a2206206994597C13D831ec7".toLowerCase()) {
+            return Result.error(-32000, "invalid opcode: opcode 0xfe not defined")
+        }
         return null
     }
 }

testing/trial/src/test/groovy/io/emeraldpay/dshackle/testing/trial/proxy/GivesErrorSpec.groovy

@@ -51,4 +51,22 @@ class GivesErrorSpec extends Specification {
             message == "invalid opcode: opcode 0xfe not defined"
         }
     }
+
+    def "Dispatch error from upstream when custome method is used"() {
+        // issue #67
+        when:
+        def call = [
+                to  : "0xdAC17F958D2ee523a2206206994597C13D831ec7",
+                from: "0xEF65ffB384c99a00403EAa22115323a555700D79",
+                data: "0xa9059cbb0000000000000000000000003f5ce5fbfe3e9af3971dd833d26ba9b5c936f0be000000000000000000000000000000000000000000000000000000004856fb60"
+        ]
+        def act = client.execute("test_foo", [call, "0x100000"])
+        then:
+        act.result == null
+        act.error != null
+        with(act.error) {
+            code == -32000
+            message == "invalid opcode: opcode 0xfe not defined"
+        }
+    }
 }