Savings module invariants (#1199)

* add deposits to genesis state

* import/export genesis with deposits

* add helper keeper method + update tests

* invariants + tests

* register invariants on module

* fix genesis test invariant init

* clean up invariants test

* remove comment from test file

* fix invariants test

* run 'make proto-all'

docs/core/proto-docs.md

@@ -375,6 +375,8 @@
 - [kava/savings/v1beta1/tx.proto](#kava/savings/v1beta1/tx.proto)
     - [MsgDeposit](#kava.savings.v1beta1.MsgDeposit)
     - [MsgDepositResponse](#kava.savings.v1beta1.MsgDepositResponse)
+    - [MsgWithdraw](#kava.savings.v1beta1.MsgWithdraw)
+    - [MsgWithdrawResponse](#kava.savings.v1beta1.MsgWithdrawResponse)
   
     - [Msg](#kava.savings.v1beta1.Msg)
   
@@ -5086,6 +5088,7 @@ GenesisState defines the savings module's genesis state.
 | Field | Type | Label | Description |
 | ----- | ---- | ----- | ----------- |
 | `params` | [Params](#kava.savings.v1beta1.Params) |  | params defines all the parameters of the module. |
+| `deposits` | [Deposit](#kava.savings.v1beta1.Deposit) | repeated |  |
 
 
 
@@ -5222,6 +5225,32 @@ MsgDepositResponse defines the Msg/Deposit response type.
 
 
 
+
+<a name="kava.savings.v1beta1.MsgWithdraw"></a>
+
+### MsgWithdraw
+MsgWithdraw defines the Msg/Withdraw request type.
+
+
+| Field | Type | Label | Description |
+| ----- | ---- | ----- | ----------- |
+| `depositor` | [string](#string) |  |  |
+| `amount` | [cosmos.base.v1beta1.Coin](#cosmos.base.v1beta1.Coin) | repeated |  |
+
+
+
+
+
+
+<a name="kava.savings.v1beta1.MsgWithdrawResponse"></a>
+
+### MsgWithdrawResponse
+MsgWithdrawResponse defines the Msg/Withdraw response type.
+
+
+
+
+
  <!-- end messages -->
 
  <!-- end enums -->
@@ -5237,6 +5266,7 @@ Msg defines the savings Msg service.
 | Method Name | Request Type | Response Type | Description | HTTP Verb | Endpoint |
 | ----------- | ------------ | ------------- | ------------| ------- | -------- |
 | `Deposit` | [MsgDeposit](#kava.savings.v1beta1.MsgDeposit) | [MsgDepositResponse](#kava.savings.v1beta1.MsgDepositResponse) | Deposit defines a method for depositing funds to the savings module account | |
+| `Withdraw` | [MsgWithdraw](#kava.savings.v1beta1.MsgWithdraw) | [MsgWithdrawResponse](#kava.savings.v1beta1.MsgWithdrawResponse) | Withdraw defines a method for withdrawing funds to the savings module account | |
 
  <!-- end services -->
 

proto/kava/savings/v1beta1/tx.proto

@@ -15,7 +15,6 @@ service Msg {
 
   // Withdraw defines a method for withdrawing funds to the savings module account
   rpc Withdraw(MsgWithdraw) returns (MsgWithdrawResponse);
-
 }
 
 // MsgDeposit defines the Msg/Deposit request type.

x/savings/genesis_test.go

@@ -42,20 +42,26 @@ func (suite *GenesisTestSuite) TestInitExportGenesis() {
 		[]string{"btc", "ukava", "bnb"},
 	)
 
+	depositAmt := sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(1e8)))
+
 	deposits := types.Deposits{
 		types.NewDeposit(
 			suite.addrs[0],
-			sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(1e8))), // 100 ukava
+			depositAmt, // 100 ukava
 		),
 	}
-
 	savingsGenesis := types.NewGenesisState(params, deposits)
 
+	authBuilder := app.NewAuthBankGenesisBuilder().
+		WithSimpleModuleAccount(types.ModuleAccountName, depositAmt)
+
+	cdc := suite.app.AppCodec()
 	suite.NotPanics(
 		func() {
 			suite.app.InitializeFromGenesisStatesWithTime(
 				suite.genTime,
-				app.GenesisState{types.ModuleName: suite.app.AppCodec().MustMarshalJSON(&savingsGenesis)},
+				authBuilder.BuildMarshalled(cdc),
+				app.GenesisState{types.ModuleName: cdc.MustMarshalJSON(&savingsGenesis)},
 			)
 		},
 	)

x/savings/keeper/invariants.go

@@ -0,0 +1,67 @@
+package keeper
+
+import (
+	"github.com/kava-labs/kava/x/savings/types"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+)
+
+// RegisterInvariants registers the savings module invariants
+func RegisterInvariants(ir sdk.InvariantRegistry, k Keeper) {
+	ir.RegisterRoute(types.ModuleName, "deposits", DepositsInvariant(k))
+	ir.RegisterRoute(types.ModuleName, "solvency", SolvencyInvariant(k))
+}
+
+// AllInvariants runs all invariants of the savings module
+func AllInvariants(k Keeper) sdk.Invariant {
+	return func(ctx sdk.Context) (string, bool) {
+		if res, stop := DepositsInvariant(k)(ctx); stop {
+			return res, stop
+		}
+
+		res, stop := SolvencyInvariant(k)(ctx)
+		return res, stop
+	}
+}
+
+// DepositsInvariant iterates all deposits and asserts that they are valid
+func DepositsInvariant(k Keeper) sdk.Invariant {
+	broken := false
+	message := sdk.FormatInvariant(types.ModuleName, "validate deposits broken", "deposit invalid")
+
+	return func(ctx sdk.Context) (string, bool) {
+		k.IterateDeposits(ctx, func(deposit types.Deposit) bool {
+			if err := deposit.Validate(); err != nil {
+				broken = true
+				return true
+			}
+			if !deposit.Amount.IsAllPositive() {
+				broken = true
+				return true
+			}
+			return false
+		})
+
+		return message, broken
+	}
+}
+
+// SolvencyInvariant iterates all deposits and ensures the total amount matches the module account coins
+func SolvencyInvariant(k Keeper) sdk.Invariant {
+	message := sdk.FormatInvariant(types.ModuleName, "module solvency broken", "total deposited amount does not match module account")
+
+	return func(ctx sdk.Context) (string, bool) {
+		balance := k.bankKeeper.GetAllBalances(ctx, k.GetSavingsModuleAccount(ctx).GetAddress())
+
+		deposited := sdk.Coins{}
+		k.IterateDeposits(ctx, func(deposit types.Deposit) bool {
+			for _, coin := range deposit.Amount {
+				deposited = deposited.Add(coin)
+			}
+			return false
+		})
+
+		broken := !deposited.IsEqual(balance)
+		return message, broken
+	}
+}

x/savings/keeper/invariants_test.go

@@ -0,0 +1,149 @@
+package keeper_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
+	tmtime "github.com/tendermint/tendermint/types/time"
+
+	"github.com/cosmos/cosmos-sdk/simapp"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	bankkeeper "github.com/cosmos/cosmos-sdk/x/bank/keeper"
+
+	"github.com/kava-labs/kava/app"
+	"github.com/kava-labs/kava/x/savings/keeper"
+	"github.com/kava-labs/kava/x/savings/types"
+)
+
+type invariantTestSuite struct {
+	suite.Suite
+
+	tApp       app.TestApp
+	ctx        sdk.Context
+	keeper     keeper.Keeper
+	bankKeeper bankkeeper.Keeper
+	addrs      []sdk.AccAddress
+	invariants map[string]map[string]sdk.Invariant
+}
+
+func (suite *invariantTestSuite) SetupTest() {
+	config := sdk.GetConfig()
+	app.SetBech32AddressPrefixes(config)
+
+	tApp := app.NewTestApp()
+	ctx := tApp.NewContext(true, tmproto.Header{Height: 1, Time: tmtime.Now()})
+
+	_, addrs := app.GeneratePrivKeyAddressPairs(1)
+	suite.addrs = addrs
+
+	suite.ctx = ctx
+	suite.keeper = tApp.GetSavingsKeeper()
+	suite.bankKeeper = tApp.GetBankKeeper()
+
+	suite.invariants = make(map[string]map[string]sdk.Invariant)
+	keeper.RegisterInvariants(suite, suite.keeper)
+}
+
+func (suite *invariantTestSuite) RegisterRoute(moduleName string, route string, invariant sdk.Invariant) {
+	_, exists := suite.invariants[moduleName]
+
+	if !exists {
+		suite.invariants[moduleName] = make(map[string]sdk.Invariant)
+	}
+
+	suite.invariants[moduleName][route] = invariant
+}
+
+func (suite *invariantTestSuite) SetupValidState() {
+	depositAmt := sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(2e8)))
+
+	suite.keeper.SetDeposit(suite.ctx, types.NewDeposit(
+		suite.addrs[0],
+		depositAmt,
+	))
+
+	err := simapp.FundModuleAccount(suite.bankKeeper, suite.ctx, types.ModuleName, depositAmt)
+	suite.Require().NoError(err)
+}
+
+func (suite *invariantTestSuite) runInvariant(route string, invariant func(k keeper.Keeper) sdk.Invariant) (string, bool) {
+	ctx := suite.ctx
+	registeredInvariant := suite.invariants[types.ModuleName][route]
+	suite.Require().NotNil(registeredInvariant)
+
+	// direct call
+	dMessage, dBroken := invariant(suite.keeper)(ctx)
+	// registered call
+	rMessage, rBroken := registeredInvariant(ctx)
+	// all call
+	aMessage, aBroken := keeper.AllInvariants(suite.keeper)(ctx)
+
+	// require matching values for direct call and registered call
+	suite.Require().Equal(dMessage, rMessage, "expected registered invariant message to match")
+	suite.Require().Equal(dBroken, rBroken, "expected registered invariant broken to match")
+	// require matching values for direct call and all invariants call if broken
+	suite.Require().Equal(dBroken, aBroken, "expected all invariant broken to match")
+	if dBroken {
+		suite.Require().Equal(dMessage, aMessage, "expected all invariant message to match")
+	}
+
+	// return message, broken
+	return dMessage, dBroken
+}
+
+func (suite *invariantTestSuite) TestDepositsInvariant() {
+	message, broken := suite.runInvariant("deposits", keeper.DepositsInvariant)
+	suite.Equal("savings: validate deposits broken invariant\ndeposit invalid\n", message)
+	suite.Equal(false, broken)
+
+	suite.SetupValidState()
+	message, broken = suite.runInvariant("deposits", keeper.DepositsInvariant)
+	suite.Equal("savings: validate deposits broken invariant\ndeposit invalid\n", message)
+	suite.Equal(false, broken)
+
+	// broken with invalid deposit
+	suite.keeper.SetDeposit(suite.ctx, types.NewDeposit(
+		suite.addrs[0],
+		sdk.Coins{},
+	))
+
+	message, broken = suite.runInvariant("deposits", keeper.DepositsInvariant)
+	suite.Equal("savings: validate deposits broken invariant\ndeposit invalid\n", message)
+	suite.Equal(true, broken)
+}
+
+func (suite *invariantTestSuite) TestSolvencyInvariant() {
+	message, broken := suite.runInvariant("solvency", keeper.SolvencyInvariant)
+	suite.Equal("savings: module solvency broken invariant\ntotal deposited amount does not match module account\n", message)
+	suite.Equal(false, broken)
+
+	suite.SetupValidState()
+	message, broken = suite.runInvariant("solvency", keeper.SolvencyInvariant)
+	suite.Equal("savings: module solvency broken invariant\ntotal deposited amount does not match module account\n", message)
+	suite.Equal(false, broken)
+
+	// broken when deposits are greater than module balance
+	suite.keeper.SetDeposit(suite.ctx, types.NewDeposit(
+		suite.addrs[0],
+		sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(3e8))),
+	))
+
+	message, broken = suite.runInvariant("solvency", keeper.SolvencyInvariant)
+	suite.Equal("savings: module solvency broken invariant\ntotal deposited amount does not match module account\n", message)
+	suite.Equal(true, broken)
+
+	// broken when deposits are less than the module balance
+	suite.keeper.SetDeposit(suite.ctx, types.NewDeposit(
+		suite.addrs[0],
+		sdk.NewCoins(sdk.NewCoin("ukava", sdk.NewInt(1e8))),
+	))
+
+	message, broken = suite.runInvariant("solvency", keeper.SolvencyInvariant)
+	suite.Equal("savings: module solvency broken invariant\ntotal deposited amount does not match module account\n", message)
+	suite.Equal(true, broken)
+}
+
+func TestInvariantTestSuite(t *testing.T) {
+	suite.Run(t, new(invariantTestSuite))
+}

x/savings/keeper/keeper.go

@@ -6,6 +6,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/store/prefix"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
 	paramtypes "github.com/cosmos/cosmos-sdk/x/params/types"
 	"github.com/tendermint/tendermint/libs/log"
 
@@ -39,6 +40,11 @@ func NewKeeper(
 	}
 }
 
+// GetSavingsModuleAccount returns the savings ModuleAccount
+func (k Keeper) GetSavingsModuleAccount(ctx sdk.Context) authtypes.ModuleAccountI {
+	return k.accountKeeper.GetModuleAccount(ctx, types.ModuleAccountName)
+}
+
 // GetDeposit returns a deposit from the store for a particular depositor address, deposit denom
 func (k Keeper) GetDeposit(ctx sdk.Context, depositor sdk.AccAddress) (types.Deposit, bool) {
 	store := prefix.NewStore(ctx.KVStore(k.key), types.DepositsKeyPrefix)

x/savings/module.go

@@ -111,7 +111,9 @@ func (am AppModule) Name() string {
 }
 
 // RegisterInvariants register module invariants
-func (am AppModule) RegisterInvariants(ir sdk.InvariantRegistry) {}
+func (am AppModule) RegisterInvariants(ir sdk.InvariantRegistry) {
+	keeper.RegisterInvariants(ir, am.keeper)
+}
 
 // Route module message route name
 func (am AppModule) Route() sdk.Route {