t8n: exclude empty requests in result, but include type byte

Reference: https://github.com/ethereum/execution-apis/pull/599/files.

Author: pdobacz

test/integration/t8n/CMakeLists.txt

@@ -146,10 +146,10 @@ add_test(
 )
 string(
     JOIN ".*" EXPECTED_OUT
-    # empty requests list of exactly 3 elements (withdrawals, deposits, consolidations)
-    [=["requests": \[[^],]*"0x",[^],]*"0x",[^],]*"0x"[^,]*\]]=]
+    # empty requests list
+    [=["requests": \[\]]=]
     # requests hash should be present
-    [=["requestsHash": "0x6036c41849da9c076ed79654d434017387a88fb833c2856b32e18218b3341c5f"]=]
+    [=["requestsHash": "0xe3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"]=]
 )
 set_tests_properties(
     ${PREFIX}/${TEST_CASE}/out.json PROPERTIES

test/t8n/t8n.cpp

@@ -255,8 +255,12 @@ int main(int argc, const char* argv[])
         {
             // EIP-7685: General purpose execution layer requests
             j_result["requests"] = json::json::array();
-            for (size_t i = 0; i < requests.size(); ++i)
-                j_result["requests"][i] = hex0x(requests[i].data());
+            for (const auto& r : requests)
+            {
+                if (!r.data().empty())
+                    // Only report non-empty requests. Include the leading type byte.
+                    j_result["requests"].emplace_back(hex0x(r.raw_data));
+            }
 
             auto requests_hash = calculate_requests_hash(requests);