No 20% tx fee cut for validators

[bedeho]

Block author still gets tip, but no inclusion fee cut of 20%, also good for tokenomics, see background https://github.com/Joystream/joystream/issues/4174

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[mnaamani]

Implemented in https://github.com/Joystream/joystream/pull/4199

[bedeho]

How to test in QA: verify that validator does not receive any tx inclusion fee revenue at all, they still should be able to receive tips.

[mnaamani]

How to test in QA: verify that validator does not receive any tx inclusion fee revenue at all, they still should be able to receive tips.

I added a basic test for correct implementation of the DealWithFees implementation in the runtime as cargo unit tests, but this is by no means a complete test coverage.

We could have simple test scenario in integration tests as follows:

• Setup Account X fund it from Alice (the block author)
• Record total issuance, and balance of Alice and X
• execute N balances:transfer() calls each with a tip T, transferring amount V to account Y
• At end of the scenario (which should be completed before the end of an Era) the following should hold:
  • Alice Balance should have increased by (N * T) only
  • Account X balance decresed by (N * T + N * V + TotalTxFeesPaid)
  • Account Y balance equal to (N * V)
  • Total Issuance reduced by TotalTxFeesPaid

we can derive TotalTxFeesPaid by BalanceOf(X) - (N * T + N * V) we can also simplify by transfering to self ie. X == Y and transferring zero balance, ie V == 0