internal/ethapi: return null for missing debug_getRawTransaction

Change DebugAPI.GetRawTransaction return type from hexutil.Bytes to
*hexutil.Bytes so that a not-found transaction serialises as JSON null
instead of "0x". Add TestRPCDebugGetRawTransaction with golden files.

internal/ethapi/api.go

@@ -2100,12 +2100,17 @@ func (api *DebugAPI) GetRawReceipts(ctx context.Context, blockNrOrHash rpc.Block
 }
 
 // GetRawTransaction returns the bytes of the transaction for the given hash.
-func (api *DebugAPI) GetRawTransaction(ctx context.Context, hash common.Hash) (hexutil.Bytes, error) {
+func (api *DebugAPI) GetRawTransaction(ctx context.Context, hash common.Hash) (*hexutil.Bytes, error) {
 	// Retrieve a finalized transaction, or a pooled otherwise
 	found, tx, _, _, _ := api.b.GetCanonicalTransaction(hash)
 	if !found {
 		if tx = api.b.GetPoolTransaction(hash); tx != nil {
-			return tx.MarshalBinary()
+			blob, err := tx.MarshalBinary()
+			if err != nil {
+				return nil, err
+			}
+			b := hexutil.Bytes(blob)
+			return &b, nil
 		}
 		// If also not in the pool there is a chance the tx indexer is still in progress.
 		if !api.b.TxIndexDone() {
@@ -2114,7 +2119,12 @@ func (api *DebugAPI) GetRawTransaction(ctx context.Context, hash common.Hash) (h
 		// Transaction is not found in the pool and the indexer is done.
 		return nil, nil
 	}
-	return tx.MarshalBinary()
+	blob, err := tx.MarshalBinary()
+	if err != nil {
+		return nil, err
+	}
+	b := hexutil.Bytes(blob)
+	return &b, nil
 }
 
 // PrintBlock retrieves a block and returns its pretty printed form.

internal/ethapi/api_test.go

@@ -4468,3 +4468,42 @@ func TestRPCGetRawTransactionByBlockNumberAndIndex(t *testing.T) {
 		testRPCResponseWithFile(t, i, result, "eth_getRawTransactionByBlockNumberAndIndex", tt.file)
 	}
 }
+
+func TestRPCDebugGetRawTransaction(t *testing.T) {
+	t.Parallel()
+
+	var (
+		backend, txHashes = setupReceiptBackend(t, 2)
+		api               = NewDebugAPI(backend)
+	)
+
+	var testSuite = []struct {
+		txHash common.Hash
+		file   string
+	}{
+		// 0. legacy transfer tx (block 0 default case)
+		{
+			txHash: txHashes[0],
+			file:   "found-legacy",
+		},
+		// 1. zero hash, not in chain
+		{
+			txHash: common.Hash{},
+			file:   "txhash-empty",
+		},
+		// 2. unknown hash, not in chain
+		{
+			txHash: common.HexToHash("deadbeef"),
+			file:   "txhash-notfound",
+		},
+	}
+
+	for i, tt := range testSuite {
+		result, err := api.GetRawTransaction(context.Background(), tt.txHash)
+		if err != nil {
+			t.Errorf("test %d: want no error, have %v", i, err)
+			continue
+		}
+		testRPCResponseWithFile(t, i, result, "debug_getRawTransaction", tt.file)
+	}
+}

internal/ethapi/testdata/debug_getRawTransaction-found-legacy.json

@@ -0,0 +1 @@
+"0xf8658084342770c0825208940d3ab14bbad3d99f4203bd7a11acb94882050e7e8203e8801ba0cd190747077598c3b9c5f21ea06f8487d6ab1e23358fbe0e0e0c4e64651b68f3a0467ebcb2186b332969991e2e25244959dcdb3feb7652ff6b81ce96e646d86abd"

internal/ethapi/testdata/debug_getRawTransaction-txhash-empty.json

@@ -0,0 +1 @@
+null

internal/ethapi/testdata/debug_getRawTransaction-txhash-notfound.json

@@ -0,0 +1 @@
+null