Hard: repay borrowed coins (#725)

* add msg borrow test

* repay types

* register msg repay on codec

* repay keeper functionality

* repay cli

* repay keeper test

* Hard: repay insufficient balance error (#726)

* repay error: insufficient balance

* isolate coin type in error msg

* add multi-coin repay example

* CalculatePaymentAmount, repay > SyncBorrowInterest

* remove todo: index updated by sync

* update tests

* add back in test

x/harvest/client/cli/tx.go

@@ -34,6 +34,7 @@ func GetTxCmd(cdc *codec.Codec) *cobra.Command {
 		getCmdWithdraw(cdc),
 		getCmdClaimReward(cdc),
 		getCmdBorrow(cdc),
+		getCmdRepay(cdc),
 	)...)
 
 	return harvestTxCmd
@@ -144,3 +145,31 @@ func getCmdBorrow(cdc *codec.Codec) *cobra.Command {
 		},
 	}
 }
+
+func getCmdRepay(cdc *codec.Codec) *cobra.Command {
+	return &cobra.Command{
+		Use:   "repay [1000000000ukava]",
+		Short: "repay tokens to the harvest protocol",
+		Long:  strings.TrimSpace(`repay tokens to the harvest protocol`),
+		Args:  cobra.ExactArgs(1),
+		Example: fmt.Sprintf(
+			`%s tx %s repay 1000000000ukava,25000000000bnb --from <key>`, version.ClientName, types.ModuleName,
+		),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			inBuf := bufio.NewReader(cmd.InOrStdin())
+			cliCtx := context.NewCLIContext().WithCodec(cdc)
+			txBldr := auth.NewTxBuilderFromCLI(inBuf).WithTxEncoder(utils.GetTxEncoder(cdc))
+
+			coins, err := sdk.ParseCoins(args[0])
+			if err != nil {
+				return err
+			}
+
+			msg := types.NewMsgRepay(cliCtx.GetFromAddress(), coins)
+			if err := msg.ValidateBasic(); err != nil {
+				return err
+			}
+			return utils.GenerateOrBroadcastMsgs(cliCtx, txBldr, []sdk.Msg{msg})
+		},
+	}
+}

x/harvest/handler.go

@@ -23,6 +23,8 @@ func NewHandler(k Keeper) sdk.Handler {
 			return handleMsgWithdraw(ctx, k, msg)
 		case types.MsgBorrow:
 			return handleMsgBorrow(ctx, k, msg)
+		case types.MsgRepay:
+			return handleMsgRepay(ctx, k, msg)
 		default:
 			return nil, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "unrecognized %s message type: %T", ModuleName, msg)
 		}
@@ -100,3 +102,21 @@ func handleMsgBorrow(ctx sdk.Context, k keeper.Keeper, msg types.MsgBorrow) (*sd
 		Events: ctx.EventManager().Events(),
 	}, nil
 }
+
+func handleMsgRepay(ctx sdk.Context, k keeper.Keeper, msg types.MsgRepay) (*sdk.Result, error) {
+	err := k.Repay(ctx, msg.Sender, msg.Amount)
+	if err != nil {
+		return nil, err
+	}
+
+	ctx.EventManager().EmitEvent(
+		sdk.NewEvent(
+			sdk.EventTypeMessage,
+			sdk.NewAttribute(sdk.AttributeKeyModule, types.AttributeValueCategory),
+			sdk.NewAttribute(sdk.AttributeKeySender, msg.Sender.String()),
+		),
+	)
+	return &sdk.Result{
+		Events: ctx.EventManager().Events(),
+	}, nil
+}

x/harvest/keeper/keeper.go

@@ -240,9 +240,13 @@ func (k Keeper) IterateBorrows(ctx sdk.Context, cb func(borrow types.Borrow) (st
 // SetBorrowedCoins sets the total amount of coins currently borrowed in the store
 func (k Keeper) SetBorrowedCoins(ctx sdk.Context, borrowedCoins sdk.Coins) {
 	store := prefix.NewStore(ctx.KVStore(k.key), types.BorrowedCoinsPrefix)
+	if borrowedCoins.Empty() {
+		store.Set([]byte{}, []byte{})
+	} else {
 		bz := k.cdc.MustMarshalBinaryBare(borrowedCoins)
 		store.Set([]byte{}, bz)
 	}
+}
 
 // GetBorrowedCoins returns an sdk.Coins object from the store representing all currently borrowed coins
 func (k Keeper) GetBorrowedCoins(ctx sdk.Context) (sdk.Coins, bool) {

x/harvest/keeper/repay.go

@@ -0,0 +1,77 @@
+package keeper
+
+import (
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
+
+	"github.com/kava-labs/kava/x/harvest/types"
+)
+
+// Repay borrowed funds
+func (k Keeper) Repay(ctx sdk.Context, sender sdk.AccAddress, coins sdk.Coins) error {
+	// Sync interest so loan is up-to-date
+	k.SyncBorrowInterest(ctx, sender, coins)
+
+	// Validate requested repay
+	err := k.ValidateRepay(ctx, sender, coins)
+	if err != nil {
+		return err
+	}
+
+	// Check borrow exists here to avoid duplicating store read in ValidateRepay
+	borrow, found := k.GetBorrow(ctx, sender)
+	if !found {
+		return types.ErrBorrowNotFound
+	}
+
+	payment := k.CalculatePaymentAmount(borrow.Amount, coins)
+
+	// Sends coins from user to Harvest module account
+	err = k.supplyKeeper.SendCoinsFromAccountToModule(ctx, sender, types.ModuleAccountName, payment)
+	if err != nil {
+		return err
+	}
+
+	// Update user's borrow in store
+	borrow.Amount = borrow.Amount.Sub(payment)
+	k.SetBorrow(ctx, borrow)
+
+	// Update total borrowed amount
+	k.DecrementBorrowedCoins(ctx, payment)
+
+	ctx.EventManager().EmitEvent(
+		sdk.NewEvent(
+			types.EventTypeHarvestRepay,
+			sdk.NewAttribute(types.AttributeKeySender, sender.String()),
+			sdk.NewAttribute(types.AttributeKeyRepayCoins, payment.String()),
+		),
+	)
+
+	return nil
+}
+
+// ValidateRepay validates a requested loan repay
+func (k Keeper) ValidateRepay(ctx sdk.Context, sender sdk.AccAddress, coins sdk.Coins) error {
+	senderAcc := k.accountKeeper.GetAccount(ctx, sender)
+	senderCoins := senderAcc.GetCoins()
+	for _, coin := range coins {
+		if senderCoins.AmountOf(coin.Denom).LT(coin.Amount) {
+			return sdkerrors.Wrapf(types.ErrInsufficientBalanceForRepay, "account can only repay up to %s%s", senderCoins.AmountOf(coin.Denom), coin.Denom)
+		}
+	}
+
+	return nil
+}
+
+// CalculatePaymentAmount prevents overpayment when repaying borrowed coins
+func (k Keeper) CalculatePaymentAmount(owed sdk.Coins, payment sdk.Coins) sdk.Coins {
+	repayment := sdk.Coins{}
+	for _, coin := range payment {
+		if coin.Amount.GT(owed.AmountOf(coin.Denom)) {
+			repayment = append(repayment, sdk.NewCoin(coin.Denom, owed.AmountOf(coin.Denom)))
+		} else {
+			repayment = append(repayment, coin)
+		}
+	}
+	return repayment
+}

x/harvest/keeper/repay_test.go

@@ -0,0 +1,225 @@
+package keeper_test
+
+import (
+	"strings"
+	"time"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	abci "github.com/tendermint/tendermint/abci/types"
+	"github.com/tendermint/tendermint/crypto"
+	tmtime "github.com/tendermint/tendermint/types/time"
+
+	"github.com/kava-labs/kava/app"
+	"github.com/kava-labs/kava/x/harvest/types"
+	"github.com/kava-labs/kava/x/pricefeed"
+)
+
+func (suite *KeeperTestSuite) TestRepay() {
+	type args struct {
+		borrower                  sdk.AccAddress
+		initialBorrowerCoins      sdk.Coins
+		initialModuleCoins        sdk.Coins
+		depositCoins              []sdk.Coin
+		borrowCoins               sdk.Coins
+		repayCoins                sdk.Coins
+		expectedAccountBalance    sdk.Coins
+		expectedModAccountBalance sdk.Coins
+	}
+
+	type errArgs struct {
+		expectPass bool
+		contains   string
+	}
+
+	type borrowTest struct {
+		name    string
+		args    args
+		errArgs errArgs
+	}
+
+	testCases := []borrowTest{
+		{
+			"valid: partial repay",
+			args{
+				borrower:             sdk.AccAddress(crypto.AddressHash([]byte("test"))),
+				initialBorrowerCoins: sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(100*KAVA_CF))),
+				initialModuleCoins:   sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(1000*KAVA_CF)), sdk.NewCoin("usdx", sdk.NewInt(1000*USDX_CF))),
+				depositCoins:         []sdk.Coin{sdk.NewCoin("ukava", sdk.NewInt(100*KAVA_CF))},
+				borrowCoins:          sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(50*KAVA_CF))),
+				repayCoins:           sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(10*KAVA_CF))),
+			},
+			errArgs{
+				expectPass: true,
+				contains:   "",
+			},
+		},
+		{
+			"valid: repay in full",
+			args{
+				borrower:             sdk.AccAddress(crypto.AddressHash([]byte("test"))),
+				initialBorrowerCoins: sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(100*KAVA_CF))),
+				initialModuleCoins:   sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(1000*KAVA_CF)), sdk.NewCoin("usdx", sdk.NewInt(1000*USDX_CF))),
+				depositCoins:         []sdk.Coin{sdk.NewCoin("ukava", sdk.NewInt(100*KAVA_CF))},
+				borrowCoins:          sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(50*KAVA_CF))),
+				repayCoins:           sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(50*KAVA_CF))),
+			},
+			errArgs{
+				expectPass: true,
+				contains:   "",
+			},
+		},
+		{
+			"valid: overpayment is adjusted",
+			args{
+				borrower:             sdk.AccAddress(crypto.AddressHash([]byte("test"))),
+				initialBorrowerCoins: sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(100*KAVA_CF))),
+				initialModuleCoins:   sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(1000*KAVA_CF)), sdk.NewCoin("usdx", sdk.NewInt(1000*USDX_CF))),
+				depositCoins:         []sdk.Coin{sdk.NewCoin("ukava", sdk.NewInt(80*KAVA_CF))}, // Deposit less so user still has some KAVA
+				borrowCoins:          sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(50*KAVA_CF))),
+				repayCoins:           sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(60*KAVA_CF))), // Exceeds borrowed coins but not user's balance
+			},
+			errArgs{
+				expectPass: true,
+				contains:   "",
+			},
+		},
+		{
+			"invalid: insufficent balance for repay",
+			args{
+				borrower:             sdk.AccAddress(crypto.AddressHash([]byte("test"))),
+				initialBorrowerCoins: sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(100*KAVA_CF))),
+				initialModuleCoins:   sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(1000*KAVA_CF)), sdk.NewCoin("usdx", sdk.NewInt(1000*USDX_CF))),
+				depositCoins:         []sdk.Coin{sdk.NewCoin("ukava", sdk.NewInt(100*KAVA_CF))},
+				borrowCoins:          sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(50*KAVA_CF))),
+				repayCoins:           sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(51*KAVA_CF))), // Exceeds user's KAVA balance
+			},
+			errArgs{
+				expectPass: false,
+				contains:   "account can only repay up to",
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		suite.Run(tc.name, func() {
+			// Initialize test app and set context
+			tApp := app.NewTestApp()
+			ctx := tApp.NewContext(true, abci.Header{Height: 1, Time: tmtime.Now()})
+
+			// Auth module genesis state
+			authGS := app.NewAuthGenState(
+				[]sdk.AccAddress{tc.args.borrower},
+				[]sdk.Coins{tc.args.initialBorrowerCoins})
+
+			// Harvest module genesis state
+			harvestGS := types.NewGenesisState(types.NewParams(
+				true,
+				types.DistributionSchedules{
+					types.NewDistributionSchedule(true, "usdx", time.Date(2020, 10, 8, 14, 0, 0, 0, time.UTC), time.Date(2020, 11, 22, 14, 0, 0, 0, time.UTC), sdk.NewCoin("hard", sdk.NewInt(5000)), time.Date(2021, 11, 22, 14, 0, 0, 0, time.UTC), types.Multipliers{types.NewMultiplier(types.Small, 0, sdk.MustNewDecFromStr("0.33")), types.NewMultiplier(types.Medium, 6, sdk.MustNewDecFromStr("0.5")), types.NewMultiplier(types.Medium, 24, sdk.OneDec())}),
+					types.NewDistributionSchedule(true, "ukava", time.Date(2020, 10, 8, 14, 0, 0, 0, time.UTC), time.Date(2020, 11, 22, 14, 0, 0, 0, time.UTC), sdk.NewCoin("hard", sdk.NewInt(5000)), time.Date(2021, 11, 22, 14, 0, 0, 0, time.UTC), types.Multipliers{types.NewMultiplier(types.Small, 0, sdk.MustNewDecFromStr("0.33")), types.NewMultiplier(types.Medium, 6, sdk.MustNewDecFromStr("0.5")), types.NewMultiplier(types.Medium, 24, sdk.OneDec())}),
+				},
+				types.DelegatorDistributionSchedules{types.NewDelegatorDistributionSchedule(
+					types.NewDistributionSchedule(true, "usdx", time.Date(2020, 10, 8, 14, 0, 0, 0, time.UTC), time.Date(2025, 10, 8, 14, 0, 0, 0, time.UTC), sdk.NewCoin("hard", sdk.NewInt(500)), time.Date(2026, 10, 8, 14, 0, 0, 0, time.UTC), types.Multipliers{types.NewMultiplier(types.Small, 0, sdk.MustNewDecFromStr("0.33")), types.NewMultiplier(types.Medium, 6, sdk.MustNewDecFromStr("0.5")), types.NewMultiplier(types.Medium, 24, sdk.OneDec())}),
+					time.Hour*24,
+				),
+				},
+				types.MoneyMarkets{
+					types.NewMoneyMarket("usdx", types.NewBorrowLimit(false, sdk.NewDec(100000000*USDX_CF), sdk.MustNewDecFromStr("1")), "usdx:usd", sdk.NewInt(USDX_CF), types.NewInterestRateModel(sdk.MustNewDecFromStr("0.05"), sdk.MustNewDecFromStr("2"), sdk.MustNewDecFromStr("0.8"), sdk.MustNewDecFromStr("10")), sdk.MustNewDecFromStr("0.05")),
+					types.NewMoneyMarket("ukava", types.NewBorrowLimit(false, sdk.NewDec(100000000*USDX_CF), sdk.MustNewDecFromStr("0.8")), "kava:usd", sdk.NewInt(KAVA_CF), types.NewInterestRateModel(sdk.MustNewDecFromStr("0.05"), sdk.MustNewDecFromStr("2"), sdk.MustNewDecFromStr("0.8"), sdk.MustNewDecFromStr("10")), sdk.MustNewDecFromStr("0.05")),
+				},
+			), types.DefaultPreviousBlockTime, types.DefaultDistributionTimes)
+
+			// Pricefeed module genesis state
+			pricefeedGS := pricefeed.GenesisState{
+				Params: pricefeed.Params{
+					Markets: []pricefeed.Market{
+						{MarketID: "usdx:usd", BaseAsset: "usdx", QuoteAsset: "usd", Oracles: []sdk.AccAddress{}, Active: true},
+						{MarketID: "kava:usd", BaseAsset: "kava", QuoteAsset: "usd", Oracles: []sdk.AccAddress{}, Active: true},
+					},
+				},
+				PostedPrices: []pricefeed.PostedPrice{
+					{
+						MarketID:      "usdx:usd",
+						OracleAddress: sdk.AccAddress{},
+						Price:         sdk.MustNewDecFromStr("1.00"),
+						Expiry:        time.Now().Add(1 * time.Hour),
+					},
+					{
+						MarketID:      "kava:usd",
+						OracleAddress: sdk.AccAddress{},
+						Price:         sdk.MustNewDecFromStr("2.00"),
+						Expiry:        time.Now().Add(1 * time.Hour),
+					},
+				},
+			}
+
+			// Initialize test application
+			tApp.InitializeFromGenesisStates(authGS,
+				app.GenesisState{pricefeed.ModuleName: pricefeed.ModuleCdc.MustMarshalJSON(pricefeedGS)},
+				app.GenesisState{types.ModuleName: types.ModuleCdc.MustMarshalJSON(harvestGS)},
+			)
+
+			// Mint coins to Harvest module account
+			supplyKeeper := tApp.GetSupplyKeeper()
+			supplyKeeper.MintCoins(ctx, types.ModuleAccountName, tc.args.initialModuleCoins)
+
+			keeper := tApp.GetHarvestKeeper()
+			suite.app = tApp
+			suite.ctx = ctx
+			suite.keeper = keeper
+
+			var err error
+
+			// Deposit coins to harvest
+			depositedCoins := sdk.NewCoins()
+			for _, depositCoin := range tc.args.depositCoins {
+				err = suite.keeper.Deposit(suite.ctx, tc.args.borrower, depositCoin)
+				suite.Require().NoError(err)
+				depositedCoins.Add(depositCoin)
+			}
+
+			// Borrow coins from harvest
+			err = suite.keeper.Borrow(suite.ctx, tc.args.borrower, tc.args.borrowCoins)
+			suite.Require().NoError(err)
+
+			err = suite.keeper.Repay(suite.ctx, tc.args.borrower, tc.args.repayCoins)
+			if tc.errArgs.expectPass {
+				suite.Require().NoError(err)
+				// If we overpaid expect an adjustment
+				repaymentCoins := suite.keeper.CalculatePaymentAmount(tc.args.borrowCoins, tc.args.repayCoins)
+
+				// Check borrower balance
+				expectedBorrowerCoins := tc.args.initialBorrowerCoins.Sub(tc.args.depositCoins).Add(tc.args.borrowCoins...).Sub(repaymentCoins)
+				acc := suite.getAccount(tc.args.borrower)
+				suite.Require().Equal(expectedBorrowerCoins, acc.GetCoins())
+
+				// Check module account balance
+				expectedModuleCoins := tc.args.initialModuleCoins.Add(tc.args.depositCoins...).Sub(tc.args.borrowCoins).Add(repaymentCoins...)
+				mAcc := suite.getModuleAccount(types.ModuleAccountName)
+				suite.Require().Equal(expectedModuleCoins, mAcc.GetCoins())
+
+				// Check user's borrow object
+				borrow, _ := suite.keeper.GetBorrow(suite.ctx, tc.args.borrower)
+				expectedBorrowCoins := tc.args.borrowCoins.Sub(repaymentCoins)
+				suite.Require().Equal(expectedBorrowCoins, borrow.Amount)
+			} else {
+				suite.Require().Error(err)
+				suite.Require().True(strings.Contains(err.Error(), tc.errArgs.contains))
+
+				// Check borrower balance (no repay coins)
+				expectedBorrowerCoins := tc.args.initialBorrowerCoins.Sub(tc.args.depositCoins).Add(tc.args.borrowCoins...)
+				acc := suite.getAccount(tc.args.borrower)
+				suite.Require().Equal(expectedBorrowerCoins, acc.GetCoins())
+
+				// Check module account balance (no repay coins)
+				expectedModuleCoins := tc.args.initialModuleCoins.Add(tc.args.depositCoins...).Sub(tc.args.borrowCoins)
+				mAcc := suite.getModuleAccount(types.ModuleAccountName)
+				suite.Require().Equal(expectedModuleCoins, mAcc.GetCoins())
+
+				// Check user's borrow object (no repay coins)
+				borrow, _ := suite.keeper.GetBorrow(suite.ctx, tc.args.borrower)
+				suite.Require().Equal(tc.args.borrowCoins, borrow.Amount)
+			}
+		})
+	}
+}

x/harvest/types/codec.go

@@ -18,5 +18,6 @@ func RegisterCodec(cdc *codec.Codec) {
 	cdc.RegisterConcrete(MsgDeposit{}, "harvest/MsgDeposit", nil)
 	cdc.RegisterConcrete(MsgWithdraw{}, "harvest/MsgWithdraw", nil)
 	cdc.RegisterConcrete(MsgBorrow{}, "harvest/MsgBorrow", nil)
+	cdc.RegisterConcrete(MsgRepay{}, "harvest/MsgRepay", nil)
 	cdc.RegisterConcrete(DistributionSchedule{}, "harvest/DistributionSchedule", nil)
 }

x/harvest/types/errors.go

@@ -55,8 +55,10 @@ var (
 	ErrGreaterThanAssetBorrowLimit = sdkerrors.Register(ModuleName, 24, "fails global asset borrow limit validation")
 	// ErrBorrowEmptyCoins error for when you cannot borrow empty coins
 	ErrBorrowEmptyCoins = sdkerrors.Register(ModuleName, 25, "cannot borrow zero coins")
+	// ErrBorrowNotFound error for when a user's borrow is not found in the store
+	ErrBorrowNotFound = sdkerrors.Register(ModuleName, 26, "borrow not found")
 	// ErrPreviousAccrualTimeNotFound error for no previous accrual time found in store
-	ErrPreviousAccrualTimeNotFound = sdkerrors.Register(ModuleName, 26, "no previous accrual time found")
+	ErrPreviousAccrualTimeNotFound = sdkerrors.Register(ModuleName, 27, "no previous accrual time found")
-	// ErrBorrowNotFound error for when borrow not found in store
+	// ErrInsufficientBalanceForRepay error for when requested repay exceeds user's balance
-	ErrBorrowNotFound = sdkerrors.Register(ModuleName, 27, "no borrow found")
+	ErrInsufficientBalanceForRepay = sdkerrors.Register(ModuleName, 29, "insufficient balance")
 )

x/harvest/types/events.go

@@ -9,6 +9,7 @@ const (
 	EventTypeHarvestWithdrawal            = "harvest_withdrawal"
 	EventTypeClaimHarvestReward           = "claim_harvest_reward"
 	EventTypeHarvestBorrow                = "harvest_borrow"
+	EventTypeHarvestRepay                 = "harvest_repay"
 	AttributeValueCategory                = ModuleName
 	AttributeKeyBlockHeight               = "block_height"
 	AttributeKeyRewardsDistribution       = "rewards_distributed"
@@ -22,4 +23,6 @@ const (
 	AttributeKeyBorrow                    = "borrow"
 	AttributeKeyBorrower                  = "borrower"
 	AttributeKeyBorrowCoins               = "borrow_coins"
+	AttributeKeySender                    = "sender"
+	AttributeKeyRepayCoins                = "repay_coins"
 )

x/harvest/types/msg.go

@@ -209,8 +209,6 @@ func (msg MsgClaimReward) GetSigners() []sdk.AccAddress {
 	return []sdk.AccAddress{msg.Sender}
 }
 
-// ---------------------------------------
-
 // MsgBorrow borrows funds from the harvest module.
 type MsgBorrow struct {
 	Borrower sdk.AccAddress `json:"borrower" yaml:"borrower"`
@@ -229,7 +227,7 @@ func NewMsgBorrow(borrower sdk.AccAddress, amount sdk.Coins) MsgBorrow {
 func (msg MsgBorrow) Route() string { return RouterKey }
 
 // Type returns a human-readable string for the message, intended for utilization within tags.
-func (msg MsgBorrow) Type() string { return "harvest_borrow" } // TODO: or just 'borrow'
+func (msg MsgBorrow) Type() string { return "harvest_borrow" }
 
 // ValidateBasic does a simple validation check that doesn't require access to any other information.
 func (msg MsgBorrow) ValidateBasic() error {
@@ -260,3 +258,53 @@ func (msg MsgBorrow) String() string {
 	Amount:   %s
 `, msg.Borrower, msg.Amount)
 }
+
+// MsgRepay repays funds to the harvest module.
+type MsgRepay struct {
+	Sender sdk.AccAddress `json:"sender" yaml:"sender"`
+	Amount sdk.Coins      `json:"amount" yaml:"amount"`
+}
+
+// NewMsgRepay returns a new MsgRepay
+func NewMsgRepay(sender sdk.AccAddress, amount sdk.Coins) MsgRepay {
+	return MsgRepay{
+		Sender: sender,
+		Amount: amount,
+	}
+}
+
+// Route return the message type used for routing the message.
+func (msg MsgRepay) Route() string { return RouterKey }
+
+// Type returns a human-readable string for the message, intended for utilization within tags.
+func (msg MsgRepay) Type() string { return "harvest_repay" }
+
+// ValidateBasic does a simple validation check that doesn't require access to any other information.
+func (msg MsgRepay) ValidateBasic() error {
+	if msg.Sender.Empty() {
+		return sdkerrors.Wrap(sdkerrors.ErrInvalidAddress, "sender address cannot be empty")
+	}
+	if !msg.Amount.IsValid() || msg.Amount.IsZero() {
+		return sdkerrors.Wrapf(sdkerrors.ErrInvalidCoins, "repay amount %s", msg.Amount)
+	}
+	return nil
+}
+
+// GetSignBytes gets the canonical byte representation of the Msg.
+func (msg MsgRepay) GetSignBytes() []byte {
+	bz := ModuleCdc.MustMarshalJSON(msg)
+	return sdk.MustSortJSON(bz)
+}
+
+// GetSigners returns the addresses of signers that must sign.
+func (msg MsgRepay) GetSigners() []sdk.AccAddress {
+	return []sdk.AccAddress{msg.Sender}
+}
+
+// String implements the Stringer interface
+func (msg MsgRepay) String() string {
+	return fmt.Sprintf(`Repay Message:
+	Sender:         %s
+	Amount:   %s
+`, msg.Sender, msg.Amount)
+}

x/harvest/types/msg_test.go

@@ -192,6 +192,82 @@ func (suite *MsgTestSuite) TestMsgClaim() {
 	}
 }
 
+func (suite *MsgTestSuite) TestMsgBorrow() {
+	type args struct {
+		borrower sdk.AccAddress
+		amount   sdk.Coins
+	}
+	addrs := []sdk.AccAddress{
+		sdk.AccAddress("test1"),
+	}
+	testCases := []struct {
+		name        string
+		args        args
+		expectPass  bool
+		expectedErr string
+	}{
+		{
+			name: "valid",
+			args: args{
+				borrower: addrs[0],
+				amount:   sdk.NewCoins(sdk.NewCoin("test", sdk.NewInt(1000000))),
+			},
+			expectPass:  true,
+			expectedErr: "",
+		},
+	}
+	for _, tc := range testCases {
+		suite.Run(tc.name, func() {
+			msg := types.NewMsgBorrow(tc.args.borrower, tc.args.amount)
+			err := msg.ValidateBasic()
+			if tc.expectPass {
+				suite.NoError(err)
+			} else {
+				suite.Error(err)
+				suite.Require().True(strings.Contains(err.Error(), tc.expectedErr))
+			}
+		})
+	}
+}
+
+func (suite *MsgTestSuite) TestMsgRepay() {
+	type args struct {
+		sender sdk.AccAddress
+		amount sdk.Coins
+	}
+	addrs := []sdk.AccAddress{
+		sdk.AccAddress("test1"),
+	}
+	testCases := []struct {
+		name        string
+		args        args
+		expectPass  bool
+		expectedErr string
+	}{
+		{
+			name: "valid",
+			args: args{
+				sender: addrs[0],
+				amount: sdk.NewCoins(sdk.NewCoin("test", sdk.NewInt(1000000))),
+			},
+			expectPass:  true,
+			expectedErr: "",
+		},
+	}
+	for _, tc := range testCases {
+		suite.Run(tc.name, func() {
+			msg := types.NewMsgRepay(tc.args.sender, tc.args.amount)
+			err := msg.ValidateBasic()
+			if tc.expectPass {
+				suite.NoError(err)
+			} else {
+				suite.Error(err)
+				suite.Require().True(strings.Contains(err.Error(), tc.expectedErr))
+			}
+		})
+	}
+}
+
 func TestMsgTestSuite(t *testing.T) {
 	suite.Run(t, new(MsgTestSuite))
 }