chore: (x/mint) improve code cov (cosmos#14066)

## Description

missed the test coverage in last audit.
ref: cosmos#13988 cosmos#13456 



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

x/mint/keeper/genesis_test.go

@@ -0,0 +1,83 @@
+package keeper_test
+
+import (
+	"testing"
+
+	"cosmossdk.io/math"
+	"github.com/golang/mock/gomock"
+	"github.com/stretchr/testify/suite"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	storetypes "github.com/cosmos/cosmos-sdk/store/types"
+	"github.com/cosmos/cosmos-sdk/testutil"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	moduletestutil "github.com/cosmos/cosmos-sdk/types/module/testutil"
+	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
+	"github.com/cosmos/cosmos-sdk/x/mint"
+	"github.com/cosmos/cosmos-sdk/x/mint/keeper"
+	minttestutil "github.com/cosmos/cosmos-sdk/x/mint/testutil"
+	"github.com/cosmos/cosmos-sdk/x/mint/types"
+)
+
+var minterAcc = authtypes.NewEmptyModuleAccount(types.ModuleName, authtypes.Minter)
+
+type GenesisTestSuite struct {
+	suite.Suite
+
+	sdkCtx        sdk.Context
+	keeper        keeper.Keeper
+	cdc           codec.BinaryCodec
+	accountKeeper types.AccountKeeper
+	key           *storetypes.KVStoreKey
+}
+
+func TestGenesisTestSuite(t *testing.T) {
+	suite.Run(t, new(GenesisTestSuite))
+}
+
+func (s *GenesisTestSuite) SetupTest() {
+	key := sdk.NewKVStoreKey(types.StoreKey)
+	testCtx := testutil.DefaultContextWithDB(s.T(), key, sdk.NewTransientStoreKey("transient_test"))
+	encCfg := moduletestutil.MakeTestEncodingConfig(mint.AppModuleBasic{})
+
+	// gomock initializations
+	ctrl := gomock.NewController(s.T())
+	s.cdc = codec.NewProtoCodec(encCfg.InterfaceRegistry)
+	s.sdkCtx = testCtx.Ctx
+	s.key = key
+
+	stakingKeeper := minttestutil.NewMockStakingKeeper(ctrl)
+	accountKeeper := minttestutil.NewMockAccountKeeper(ctrl)
+	bankKeeper := minttestutil.NewMockBankKeeper(ctrl)
+	s.accountKeeper = accountKeeper
+	accountKeeper.EXPECT().GetModuleAddress(minterAcc.Name).Return(minterAcc.GetAddress())
+	accountKeeper.EXPECT().GetModuleAccount(s.sdkCtx, minterAcc.Name).Return(minterAcc)
+
+	s.keeper = keeper.NewKeeper(s.cdc, key, stakingKeeper, accountKeeper, bankKeeper, "", "")
+}
+
+func (s *GenesisTestSuite) TestImportExportGenesis() {
+	genesisState := types.DefaultGenesisState()
+	genesisState.Minter = types.NewMinter(sdk.NewDecWithPrec(20, 2), math.LegacyNewDec(1))
+	genesisState.Params = types.NewParams(
+		"testDenom",
+		sdk.NewDecWithPrec(15, 2),
+		sdk.NewDecWithPrec(22, 2),
+		sdk.NewDecWithPrec(9, 2),
+		sdk.NewDecWithPrec(69, 2),
+		uint64(60*60*8766/5),
+	)
+
+	s.keeper.InitGenesis(s.sdkCtx, s.accountKeeper, genesisState)
+
+	minter := s.keeper.GetMinter(s.sdkCtx)
+	s.Require().Equal(genesisState.Minter, minter)
+
+	invalidCtx := testutil.DefaultContextWithDB(s.T(), s.key, sdk.NewTransientStoreKey("transient_test"))
+	s.Require().Panics(func() { s.keeper.GetMinter(invalidCtx.Ctx) }, "stored minter should not have been nil")
+	params := s.keeper.GetParams(s.sdkCtx)
+	s.Require().Equal(genesisState.Params, params)
+
+	genesisState2 := s.keeper.ExportGenesis(s.sdkCtx)
+	s.Require().Equal(genesisState, genesisState2)
+}

x/mint/keeper/keeper.go

@@ -72,7 +72,7 @@ func (k Keeper) GetMinter(ctx sdk.Context) (minter types.Minter) {
 	return
 }
 
-// GetMinter sets the minter.
+// SetMinter sets the minter.
 func (k Keeper) SetMinter(ctx sdk.Context, minter types.Minter) {
 	store := ctx.KVStore(k.storeKey)
 	bz := k.cdc.MustMarshal(&minter)

x/mint/keeper/keeper_test.go

@@ -20,9 +20,11 @@ import (
 type IntegrationTestSuite struct {
 	suite.Suite
 
-	mintKeeper keeper.Keeper
-	ctx        sdk.Context
-	msgServer  types.MsgServer
+	mintKeeper    keeper.Keeper
+	ctx           sdk.Context
+	msgServer     types.MsgServer
+	stakingKeeper *minttestutil.MockStakingKeeper
+	bankKeeper    *minttestutil.MockBankKeeper
 }
 
 func TestKeeperTestSuite(t *testing.T) {
@@ -52,6 +54,11 @@ func (s *IntegrationTestSuite) SetupTest() {
 		authtypes.FeeCollectorName,
 		authtypes.NewModuleAddress(govtypes.ModuleName).String(),
 	)
+	s.stakingKeeper = stakingKeeper
+	s.bankKeeper = bankKeeper
+
+	s.Require().Equal(testCtx.Ctx.Logger().With("module", "x/"+types.ModuleName),
+		s.mintKeeper.Logger(testCtx.Ctx))
 
 	err := s.mintKeeper.SetParams(s.ctx, types.DefaultParams())
 	s.Require().NoError(err)
@@ -110,3 +117,22 @@ func (s *IntegrationTestSuite) TestParams() {
 		})
 	}
 }
+
+func (s *IntegrationTestSuite) TestAliasFunctions() {
+	stakingTokenSupply := sdk.NewIntFromUint64(100000000000)
+	s.stakingKeeper.EXPECT().StakingTokenSupply(s.ctx).Return(stakingTokenSupply)
+	s.Require().Equal(s.mintKeeper.StakingTokenSupply(s.ctx), stakingTokenSupply)
+
+	bondedRatio := sdk.NewDecWithPrec(15, 2)
+	s.stakingKeeper.EXPECT().BondedRatio(s.ctx).Return(bondedRatio)
+	s.Require().Equal(s.mintKeeper.BondedRatio(s.ctx), bondedRatio)
+
+	coins := sdk.NewCoins(sdk.NewCoin("stake", sdk.NewInt(1000000)))
+	s.bankKeeper.EXPECT().MintCoins(s.ctx, types.ModuleName, coins).Return(nil)
+	s.Require().Equal(s.mintKeeper.MintCoins(s.ctx, sdk.NewCoins()), nil)
+	s.Require().Nil(s.mintKeeper.MintCoins(s.ctx, coins))
+
+	fees := sdk.NewCoins(sdk.NewCoin("stake", sdk.NewInt(1000)))
+	s.bankKeeper.EXPECT().SendCoinsFromModuleToModule(s.ctx, types.ModuleName, authtypes.FeeCollectorName, fees).Return(nil)
+	s.Require().Nil(s.mintKeeper.AddCollectedFees(s.ctx, fees))
+}

x/mint/types/params.go

@@ -10,6 +10,7 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
+// NewParams returns Params instance with the given values.
 func NewParams(mintDenom string, inflationRateChange, inflationMax, inflationMin, goalBonded sdk.Dec, blocksPerYear uint64) Params {
 	return Params{
 		MintDenom:           mintDenom,