simulators/ethereum/engine: Add ForkchoiceUpdated with Invalid Payload Attributes Test

simulators/ethereum/engine/README.md

@@ -64,6 +64,10 @@ Perform a forkchoiceUpdated call with an unknown (random) SafeBlockHash, the cli
 - Unknown FinalizedBlockHash:  
 Perform a forkchoiceUpdated call with an unknown (random) FinalizedBlockHash, the client should throw an error.
 
+- Invalid Payload Attributes:
+Perform a forkchoiceUpdated call with valid forkchoice but invalid payload attributes.
+Expected outcome is that the forkchoiceUpdate proceeds, but the call returns an error.
+
 - Pre-TTD Block Hash:  
 Perform a forkchoiceUpdated call using a block hash part of the canonical chain that precedes the block where the TTD occurred. (Behavior is undefined for this edge case and not verified, but should not produce unrecoverable error)
 

simulators/ethereum/engine/enginetests.go

@@ -50,6 +50,14 @@ var engineTests = []TestSpec{
 		Name: "Unknown FinalizedBlockHash",
 		Run:  unknownFinalizedBlockHash,
 	},
+	{
+		Name: "ForkchoiceUpdated Invalid Payload Attributes",
+		Run:  invalidPayloadAttributesGen(false),
+	},
+	{
+		Name: "ForkchoiceUpdated Invalid Payload Attributes (Syncing)",
+		Run:  invalidPayloadAttributesGen(true),
+	},
 	{
 		Name: "Pre-TTD ForkchoiceUpdated After PoS Switch",
 		Run:  preTTDFinalizedBlockHash,
@@ -377,6 +385,63 @@ func unknownHeadBlockHash(t *TestEnv) {
 
 }
 
+// Verify behavior on a forkchoiceUpdated with invalid payload attributes
+func invalidPayloadAttributesGen(syncing bool) func(*TestEnv) {
+
+	return func(t *TestEnv) {
+		// Wait until TTD is reached by this client
+		t.CLMock.waitForTTD()
+
+		// Produce blocks before starting the test
+		t.CLMock.produceBlocks(5, BlockProcessCallbacks{})
+
+		// Send a forkchoiceUpdated with invalid PayloadAttributes
+		t.CLMock.produceSingleBlock(BlockProcessCallbacks{
+			OnNewPayloadBroadcast: func() {
+				// Try to apply the new payload with invalid attributes
+				var blockHash common.Hash
+				if syncing {
+					// Setting a random hash will put the client into `SYNCING`
+					rand.Read(blockHash[:])
+				} else {
+					// Set the block hash to the next payload that was broadcasted
+					blockHash = t.CLMock.LatestPayloadBuilt.BlockHash
+				}
+				t.Logf("INFO (%s): Sending EngineForkchoiceUpdatedV1 (Syncing=%s) with invalid payload attributes", t.TestName, syncing)
+				fcu := ForkchoiceStateV1{
+					HeadBlockHash:      blockHash,
+					SafeBlockHash:      blockHash,
+					FinalizedBlockHash: blockHash,
+				}
+				attr := PayloadAttributesV1{
+					Timestamp:             0,
+					PrevRandao:            common.Hash{},
+					SuggestedFeeRecipient: common.Address{},
+				}
+				// 0) Check headBlock is known and there is no missing data, if not respond with SYNCING
+				// 1) Check headBlock is VALID, if not respond with INVALID
+				// 2) Apply forkchoiceState
+				// 3) Check payloadAttributes, if invalid respond with error: code: Invalid payload attributes
+				// 4) Start payload build process and respond with VALID
+				if syncing {
+					// If we are SYNCING, the outcome should be SYNCING regardless of the validity of the payload atttributes
+					r := t.TestEngine.TestEngineForkchoiceUpdatedV1(&fcu, &attr)
+					r.ExpectPayloadStatus(Syncing)
+					r.ExpectPayloadID(nil)
+				} else {
+					r := t.TestEngine.TestEngineForkchoiceUpdatedV1(&fcu, &attr)
+					r.ExpectError()
+
+					// Check that the forkchoice was applied, regardless of the error
+					s := t.TestEth.TestHeaderByNumber(nil)
+					s.ExpectHash(blockHash)
+				}
+			},
+		})
+	}
+
+}
+
 // Verify that a forkchoiceUpdated fails on hash being set to a pre-TTD block after PoS change
 func preTTDFinalizedBlockHash(t *TestEnv) {
 	// Wait until TTD is reached by this client