feat!: Ensure InitGenesis returns with non-empty validator set (cosmo…

…s#9697)

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## Description

Closes: cosmos#8961 

SDK allows InitGenesis to return with an empty validator set. In practice, the error for an empty validator set gets thrown in tendermint. To fix this,

* Add non-empty validator set check to the `mm.InitGenesis` function. This will break `simapp.Setup` because it relies on an empty validator set [#comment](cosmos#8909 (comment)).
* Update `simapp.Setup` to use a single validator.
* Fix failing tests (Most of them are keeper tests).

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---

### 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...

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

sim_test.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"math/rand"
 	"os"
+	"runtime/debug"
+	"strings"
 	"testing"
 
 	storetypes "github.com/cosmos/cosmos-sdk/store/types"
@@ -153,6 +155,17 @@ func TestAppImportExport(t *testing.T) {
 	err = json.Unmarshal(exported.AppState, &genesisState)
 	require.NoError(t, err)
 
+	defer func() {
+		if r := recover(); r != nil {
+			err := fmt.Sprintf("%v", r)
+			if !strings.Contains(err, "validator set is empty after InitGenesis") {
+				panic(r)
+			}
+			logger.Info("Skipping simulation as all validators have been unbonded")
+			logger.Info("err", err, "stacktrace", string(debug.Stack()))
+		}
+	}()
+
 	ctxA := app.NewContext(true, tmproto.Header{Height: app.LastBlockHeight()})
 	ctxB := newApp.NewContext(true, tmproto.Header{Height: app.LastBlockHeight()})
 	newApp.mm.InitGenesis(ctxB, app.AppCodec(), genesisState)

test_helpers.go

@@ -121,22 +121,24 @@ func NewSimappWithCustomOptions(t *testing.T, isCheckTx bool, options SetupOptio
 func Setup(t *testing.T, isCheckTx bool) *SimApp {
 	t.Helper()
 
-	app, genesisState := setup(!isCheckTx, 5)
-	if !isCheckTx {
-		// init chain must be called to stop deliverState from being nil
-		stateBytes, err := json.MarshalIndent(genesisState, "", " ")
-		require.NoError(t, err)
+	privVal := mock.NewPV()
+	pubKey, err := privVal.GetPubKey()
+	require.NoError(t, err)
 
-		// Initialize the chain
-		app.InitChain(
-			abci.RequestInitChain{
-				Validators:      []abci.ValidatorUpdate{},
-				ConsensusParams: DefaultConsensusParams,
-				AppStateBytes:   stateBytes,
-			},
-		)
+	// create validator set with single validator
+	validator := tmtypes.NewValidator(pubKey, 1)
+	valSet := tmtypes.NewValidatorSet([]*tmtypes.Validator{validator})
+
+	// generate genesis account
+	senderPrivKey := secp256k1.GenPrivKey()
+	acc := authtypes.NewBaseAccount(senderPrivKey.PubKey().Address().Bytes(), senderPrivKey.PubKey(), 0, 0)
+	balance := banktypes.Balance{
+		Address: acc.GetAddress().String(),
+		Coins:   sdk.NewCoins(sdk.NewCoin(sdk.DefaultBondDenom, sdk.NewInt(100000000000000))),
 	}
 
+	app := SetupWithGenesisValSet(t, valSet, []authtypes.GenesisAccount{acc}, balance)
+
 	return app
 }
 
@@ -181,8 +183,13 @@ func genesisStateWithValSet(t *testing.T,
 
 	totalSupply := sdk.NewCoins()
 	for _, b := range balances {
-		// add genesis acc tokens and delegated tokens to total supply
-		totalSupply = totalSupply.Add(b.Coins.Add(sdk.NewCoin(sdk.DefaultBondDenom, bondAmt))...)
+		// add genesis acc tokens to total supply
+		totalSupply = totalSupply.Add(b.Coins...)
+	}
+
+	for range delegations {
+		// add delegated tokens to total supply
+		totalSupply = totalSupply.Add(sdk.NewCoin(sdk.DefaultBondDenom, bondAmt))
 	}
 
 	// add bonded amount to bonded pool module account
@@ -237,33 +244,44 @@ func SetupWithGenesisValSet(t *testing.T, valSet *tmtypes.ValidatorSet, genAccs
 func SetupWithGenesisAccounts(t *testing.T, genAccs []authtypes.GenesisAccount, balances ...banktypes.Balance) *SimApp {
 	t.Helper()
 
-	app, genesisState := setup(true, 0)
-	authGenesis := authtypes.NewGenesisState(authtypes.DefaultParams(), genAccs)
-	genesisState[authtypes.ModuleName] = app.AppCodec().MustMarshalJSON(authGenesis)
+	privVal := mock.NewPV()
+	pubKey, err := privVal.GetPubKey()
+	require.NoError(t, err)
 
-	totalSupply := sdk.NewCoins()
-	for _, b := range balances {
-		totalSupply = totalSupply.Add(b.Coins...)
-	}
+	// create validator set with single validator
+	validator := tmtypes.NewValidator(pubKey, 1)
+	valSet := tmtypes.NewValidatorSet([]*tmtypes.Validator{validator})
 
-	bankGenesis := banktypes.NewGenesisState(banktypes.DefaultGenesisState().Params, balances, totalSupply, []banktypes.Metadata{})
-	genesisState[banktypes.ModuleName] = app.AppCodec().MustMarshalJSON(bankGenesis)
+	return SetupWithGenesisValSet(t, valSet, genAccs, balances...)
+}
 
-	stateBytes, err := json.MarshalIndent(genesisState, "", " ")
+// SetupWithGenesisValSet initializes GenesisState with a single validator and genesis accounts
+// that also act as delegators.
+func GenesisStateWithSingleValidator(t *testing.T, app *SimApp) GenesisState {
+	t.Helper()
+
+	privVal := mock.NewPV()
+	pubKey, err := privVal.GetPubKey()
 	require.NoError(t, err)
 
-	app.InitChain(
-		abci.RequestInitChain{
-			Validators:      []abci.ValidatorUpdate{},
-			ConsensusParams: DefaultConsensusParams,
-			AppStateBytes:   stateBytes,
+	// create validator set with single validator
+	validator := tmtypes.NewValidator(pubKey, 1)
+	valSet := tmtypes.NewValidatorSet([]*tmtypes.Validator{validator})
+
+	// generate genesis account
+	senderPrivKey := secp256k1.GenPrivKey()
+	acc := authtypes.NewBaseAccount(senderPrivKey.PubKey().Address().Bytes(), senderPrivKey.PubKey(), 0, 0)
+	balances := []banktypes.Balance{
+		{
+			Address: acc.GetAddress().String(),
+			Coins:   sdk.NewCoins(sdk.NewCoin(sdk.DefaultBondDenom, sdk.NewInt(100000000000000))),
 		},
-	)
+	}
 
-	app.Commit()
-	app.BeginBlock(abci.RequestBeginBlock{Header: tmproto.Header{Height: app.LastBlockHeight() + 1}})
+	genesisState := NewDefaultGenesisState(app.appCodec)
+	genesisState = genesisStateWithValSet(t, app, genesisState, valSet, []authtypes.GenesisAccount{acc}, balances...)
 
-	return app
+	return genesisState
 }
 
 type GenerateAccountStrategy func(int) []sdk.AccAddress