From e2df5a11877f4c36144ae41dd8a7e7599fb09984 Mon Sep 17 00:00:00 2001
From: Aleksandr Bezobchuk <aleks.bezobchuk@gmail.com>
Date: Fri, 19 Jul 2019 13:48:46 -0400
Subject: [PATCH] Allow the use of a custom genesis time

---
 simapp/sim_test.go       | 13 ++++++++++---
 simapp/utils.go          |  1 +
 x/simulation/simulate.go | 26 +++++++++++++-------------
 3 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/simapp/sim_test.go b/simapp/sim_test.go
index 59a9b6d4ad41..d4a6ce3bcbd6 100644
--- a/simapp/sim_test.go
+++ b/simapp/sim_test.go
@@ -43,6 +43,7 @@ func init() {
 	flag.IntVar(&period, "SimulationPeriod", 1, "run slow invariants only once every period assertions")
 	flag.BoolVar(&onOperation, "SimulateEveryOperation", false, "run slow invariants every operation")
 	flag.BoolVar(&allInvariants, "PrintAllInvariants", false, "print all invariants if a broken invariant is found")
+	flag.Int64Var(&genesisTime, "GenesisTime", 0, "override genesis UNIX time instead of using a random UNIX time")
 }
 
 // helper function for populating input for SimulateFromSeed
@@ -56,11 +57,17 @@ func getSimulateFromSeedInput(tb testing.TB, w io.Writer, app *SimApp) (
 }
 
 func appStateFn(
-	r *rand.Rand, accs []simulation.Account, genesisTimestamp time.Time,
-) (appState json.RawMessage, simAccs []simulation.Account, chainID string) {
+	r *rand.Rand, accs []simulation.Account,
+) (appState json.RawMessage, simAccs []simulation.Account, chainID string, genesisTimestamp time.Time) {
 
 	cdc := MakeCodec()
 
+	if genesisTime == 0 {
+		genesisTimestamp = simulation.RandTimestamp(r)
+	} else {
+		genesisTimestamp = time.Unix(genesisTime, 0)
+	}
+
 	switch {
 	case paramsFile != "" && genesisFile != "":
 		panic("cannot provide both a genesis file and a params file")
@@ -83,7 +90,7 @@ func appStateFn(
 		appState, simAccs, chainID = appStateRandomizedFn(r, accs, genesisTimestamp, appParams)
 	}
 
-	return appState, simAccs, chainID
+	return appState, simAccs, chainID, genesisTimestamp
 }
 
 // TODO refactor out random initialization code to the modules
diff --git a/simapp/utils.go b/simapp/utils.go
index 0624b4e9fd13..f2e2a0a204a4 100644
--- a/simapp/utils.go
+++ b/simapp/utils.go
@@ -49,6 +49,7 @@ var (
 	period        int
 	onOperation   bool // TODO Remove in favor of binary search for invariant violation
 	allInvariants bool
+	genesisTime   int64
 )
 
 // NewSimAppUNSAFE is used for debugging purposes only.
diff --git a/x/simulation/simulate.go b/x/simulation/simulate.go
index 08920e295348..16257b864381 100644
--- a/x/simulation/simulate.go
+++ b/x/simulation/simulate.go
@@ -19,15 +19,16 @@ import (
 )
 
 // AppStateFn returns the app state json bytes, the genesis accounts, and the chain identifier
-type AppStateFn func(r *rand.Rand, accs []Account, genesisTimestamp time.Time) (appState json.RawMessage, accounts []Account, chainId string)
+type AppStateFn func(
+	r *rand.Rand, accs []Account,
+) (appState json.RawMessage, accounts []Account, chainId string, genesisTimestamp time.Time)
 
 // initialize the chain for the simulation
 func initChain(
-	r *rand.Rand, params Params, accounts []Account,
-	app *baseapp.BaseApp, appStateFn AppStateFn, genesisTimestamp time.Time,
-) (mockValidators, []Account) {
+	r *rand.Rand, params Params, accounts []Account, app *baseapp.BaseApp, appStateFn AppStateFn,
+) (mockValidators, time.Time, []Account) {
 
-	appState, accounts, chainID := appStateFn(r, accounts, genesisTimestamp)
+	appState, accounts, chainID, genesisTimestamp := appStateFn(r, accounts)
 
 	req := abci.RequestInitChain{
 		AppStateBytes: appState,
@@ -36,7 +37,7 @@ func initChain(
 	res := app.InitChain(req)
 	validators := newMockValidators(r, res.Validators, params)
 
-	return validators, accounts
+	return validators, genesisTimestamp, accounts
 }
 
 // SimulateFromSeed tests an application by running the provided
@@ -58,23 +59,22 @@ func SimulateFromSeed(
 	params := RandomParams(r)
 	fmt.Fprintf(w, "Randomized simulation params: \n%s\n", mustMarshalJSONIndent(params))
 
-	genesisTimestamp := RandTimestamp(r)
-	fmt.Printf(
-		"Starting the simulation from time %v, unixtime %v\n",
-		genesisTimestamp.UTC().Format(time.UnixDate), genesisTimestamp.Unix(),
-	)
-
 	timeDiff := maxTimePerBlock - minTimePerBlock
 	accs := RandomAccounts(r, params.NumKeys)
 	eventStats := newEventStats()
 
 	// Second variable to keep pending validator set (delayed one block since
 	// TM 0.24) Initially this is the same as the initial validator set
-	validators, accs := initChain(r, params, accs, app, appStateFn, genesisTimestamp)
+	validators, genesisTimestamp, accs := initChain(r, params, accs, app, appStateFn)
 	if len(accs) == 0 {
 		return true, fmt.Errorf("must have greater than zero genesis accounts")
 	}
 
+	fmt.Printf(
+		"Starting the simulation from time %v (unixtime %v)\n",
+		genesisTimestamp.UTC().Format(time.UnixDate), genesisTimestamp.Unix(),
+	)
+
 	// remove module account address if they exist in accs
 	var tmpAccs []Account
 	for _, acc := range accs {