feat: add genesis modification function to e2e (#2112)

## Description

Configures genesis properly for passing gov proposals. See #2071 for passing tests

closes: #2077 

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

- [ ] Targeted PR against correct branch (see [CONTRIBUTING.md](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Code follows the [module structure standards](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules/structure.md).
- [ ] Wrote unit and integration [tests](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#testing)
- [ ] Updated relevant documentation (`docs/`) or specification (`x/<module>/spec/`)
- [ ] Added relevant `godoc` [comments](https://blog.golang.org/godoc-documenting-go-code).
- [ ] Added a relevant changelog entry to the `Unreleased` section in `CHANGELOG.md`
- [ ] Re-reviewed `Files changed` in the Github PR explorer
- [ ] Review `Codecov Report` in the comment section below once CI passes

e2e/testconfig/testconfig.go

@@ -1,10 +1,21 @@
 package testconfig
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 
+	"github.com/cosmos/cosmos-sdk/codec"
+	simappparams "github.com/cosmos/cosmos-sdk/simapp/params"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	genutiltypes "github.com/cosmos/cosmos-sdk/x/genutil/types"
+	govtypes "github.com/cosmos/cosmos-sdk/x/gov/types"
+	govv1beta1 "github.com/cosmos/cosmos-sdk/x/gov/types/v1beta1"
 	"github.com/strangelove-ventures/ibctest/ibc"
+	tmjson "github.com/tendermint/tendermint/libs/json"
+	tmtypes "github.com/tendermint/tendermint/types"
+
+	"github.com/cosmos/ibc-go/e2e/testvalues"
 )
 
 const (
@@ -150,3 +161,51 @@ func newDefaultSimappConfig(cc ChainConfig, name, chainID, denom string) ibc.Cha
 		NoHostMount:    false,
 	}
 }
+
+// defaultModifyGenesis will only modify governance params to ensure the voting period and minimum deposit
+// are functional for e2e testing purposes.
+func defaultModifyGenesis(denom string) func([]byte) ([]byte, error) {
+	return func(genbz []byte) ([]byte, error) {
+		genDoc, err := tmtypes.GenesisDocFromJSON(genbz)
+		if err != nil {
+			return nil, fmt.Errorf("failed to unmarshal genesis bytes into genesis doc: %w", err)
+		}
+
+		var appState genutiltypes.AppMap
+		if err := json.Unmarshal(genDoc.AppState, &appState); err != nil {
+			return nil, fmt.Errorf("failed to unmarshal genesis bytes into app state: %w", err)
+		}
+
+		cfg := simappparams.MakeTestEncodingConfig()
+		govv1beta1.RegisterInterfaces(cfg.InterfaceRegistry)
+		cdc := codec.NewProtoCodec(cfg.InterfaceRegistry)
+
+		govGenesisState := &govv1beta1.GenesisState{}
+		if err := cdc.UnmarshalJSON(appState[govtypes.ModuleName], govGenesisState); err != nil {
+			return nil, fmt.Errorf("failed to unmarshal genesis bytes into gov genesis state: %w", err)
+		}
+
+		// set correct minimum deposit using configured denom
+		govGenesisState.DepositParams.MinDeposit = sdk.NewCoins(sdk.NewCoin(denom, govv1beta1.DefaultMinDepositTokens))
+		govGenesisState.VotingParams.VotingPeriod = testvalues.VotingPeriod
+
+		govGenBz, err := cdc.MarshalJSON(govGenesisState)
+		if err != nil {
+			return nil, fmt.Errorf("failed to marshal gov genesis state: %w", err)
+		}
+
+		appState[govtypes.ModuleName] = govGenBz
+
+		genDoc.AppState, err = json.Marshal(appState)
+		if err != nil {
+			return nil, err
+		}
+
+		bz, err := tmjson.MarshalIndent(genDoc, "", "  ")
+		if err != nil {
+			return nil, err
+		}
+
+		return bz, nil
+	}
+}

e2e/testvalues/values.go

@@ -1,16 +1,19 @@
 package testvalues
 
 import (
+	"time"
+
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/strangelove-ventures/ibctest/ibc"
 
 	feetypes "github.com/cosmos/ibc-go/v5/modules/apps/29-fee/types"
 )
 
 const (
-	StartingTokenAmount int64  = 100_000_000
-	IBCTransferAmount   int64  = 10_000
-	InvalidAddress      string = "<invalid-address>"
+	StartingTokenAmount int64         = 100_000_000
+	IBCTransferAmount   int64         = 10_000
+	InvalidAddress      string        = "<invalid-address>"
+	VotingPeriod        time.Duration = time.Second * 30
 )
 
 // ImmediatelyTimeout returns an ibc.IBCTimeout which will cause an IBC transfer to timeout immediately.