**Current Problem**
When X transactions are created, with M transactions out of them having
`gasFeeCap` greater than the current `baseFeePerGas` for the block, and
N transactions having `gasFeeCap` lower, all X transactions get added to
the yellow pool (baseFee) in the txpool and they never get mined.
However when X transactions all having `gasFeeCap` higher than the
`baseFeePerGas` are created, they all get added to the green pool
(pending) in the txpool and thus get mined.
This phenomenon can be inspected in the
`signEIP1559TxsLowerAndHigherThanBaseFee2` function where the number of
transactions that should have `gasFeeCap` higher than and lower than the
current `baseFeePerGas` is specified in its parameter - `func
signEIP1559TxsLowerAndHigherThanBaseFee2(amountLower, amountHigher
int...`.
When `amountLower` is set as `0`, all transactions created from
`amountHigher` will be mined because they have `gasFeeCap` >
`baseFeePerGas`. When `amountLower` has a value > `0`, all the
transactions created (including transactions created with
`amountHigher`) will go to the yellow pool (baseFee) and thus do not get
mined.
- Added listening methods for WebSocket subscriptions
- Listened for new blocks using the newHeads method to determine when to
look for a transaction
- Added new util methods and tests for them
- Simplified communication to the user upon initiating the devnet tool
