* TestMintCoinsToFeeCollectorAndGetProportions refactor

* TestDistrAssetToDeveloperRewardsAddrWhenNotEmpty refactor

* add feePool and feeCollector check

* comment

* use hasPreExistingSupply and better readable mintKeeper

* Update x/mint/keeper/keeper_test.go

Co-authored-by: Matt, Park <[email protected]>

* Update x/mint/keeper/keeper_test.go

Co-authored-by: Matt, Park <[email protected]>

* add testcase when nil dev reward address

* use shorter keeper name for better readability

Co-authored-by: Matt, Park <[email protected]>
(cherry picked from commit ed55aebc

)

Co-authored-by: vuong <[email protected]>