Implement eth_getTransactionByHash JSON RPC function

Author: Bhargavasomu

trinity/rpc/modules/eth.py

@@ -247,6 +247,15 @@ async def getTransactionCount(self, address: Address, at_block: Union[str, int])
         nonce = account_db.get_nonce(address)
         return hex(nonce)
 
+    @format_params(decode_hex)
+    async def getTransactionByHash(self, transaction_hash: Hash32) -> Dict[str, str]:
+        transaction_block_number, transaction_index = self._chain.chaindb.get_transaction_index(
+            transaction_hash
+        )
+        block = await get_block_at_number(self._chain, transaction_block_number)
+        transaction = block.transactions[transaction_index]
+        return transaction_to_dict(transaction)
+
     @format_params(decode_hex)
     async def getUncleCountByBlockHash(self, block_hash: Hash32) -> str:
         block = await self._chain.coro_get_block_by_hash(block_hash)