From cf6b7ef6d85781100e254cb535724c085ef74df9 Mon Sep 17 00:00:00 2001
From: Christopher Goes <cwgoes@pluranimity.org>
Date: Thu, 15 Nov 2018 22:21:42 +0100
Subject: [PATCH] Test runtime-assertable invariants every block (#2807)

* Initial pass
* Minor cleanup
---
 PENDING.md                 |  1 +
 cmd/gaia/app/app.go        |  2 ++
 cmd/gaia/app/invariants.go | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 cmd/gaia/app/invariants.go

diff --git a/PENDING.md b/PENDING.md
index 357d1c8b0b79..ba90d3ac8fd5 100644
--- a/PENDING.md
+++ b/PENDING.md
@@ -34,6 +34,7 @@ FEATURES
   * [app] \#2791 Support export at a specific height, with `gaiad export --height=HEIGHT`.
   * [x/gov] [#2479](https://github.com/cosmos/cosmos-sdk/issues/2479) Implemented querier
   for getting governance parameters.
+  * [app] \#2663 - Runtime-assertable invariants
   * [app] \#2791 Support export at a specific height, with `gaiad export --height=HEIGHT`.
 
 * SDK
diff --git a/cmd/gaia/app/app.go b/cmd/gaia/app/app.go
index 25265a3611f2..fb8455b5aea8 100644
--- a/cmd/gaia/app/app.go
+++ b/cmd/gaia/app/app.go
@@ -210,6 +210,8 @@ func (app *GaiaApp) EndBlocker(ctx sdk.Context, req abci.RequestEndBlock) abci.R
 	tags := gov.EndBlocker(ctx, app.govKeeper)
 	validatorUpdates := stake.EndBlocker(ctx, app.stakeKeeper)
 
+	app.assertRuntimeInvariants()
+
 	return abci.ResponseEndBlock{
 		ValidatorUpdates: validatorUpdates,
 		Tags:             tags,
diff --git a/cmd/gaia/app/invariants.go b/cmd/gaia/app/invariants.go
new file mode 100644
index 000000000000..67ec1c71414a
--- /dev/null
+++ b/cmd/gaia/app/invariants.go
@@ -0,0 +1,34 @@
+package app
+
+import (
+	"fmt"
+	"time"
+
+	banksim "github.com/cosmos/cosmos-sdk/x/bank/simulation"
+	distrsim "github.com/cosmos/cosmos-sdk/x/distribution/simulation"
+	"github.com/cosmos/cosmos-sdk/x/mock/simulation"
+	stakesim "github.com/cosmos/cosmos-sdk/x/stake/simulation"
+)
+
+func (app *GaiaApp) runtimeInvariants() []simulation.Invariant {
+	return []simulation.Invariant{
+		banksim.NonnegativeBalanceInvariant(app.accountKeeper),
+		distrsim.ValAccumInvariants(app.distrKeeper, app.stakeKeeper),
+		stakesim.SupplyInvariants(app.bankKeeper, app.stakeKeeper,
+			app.feeCollectionKeeper, app.distrKeeper, app.accountKeeper),
+		stakesim.PositivePowerInvariant(app.stakeKeeper),
+	}
+}
+
+func (app *GaiaApp) assertRuntimeInvariants() {
+	invariants := app.runtimeInvariants()
+	start := time.Now()
+	for _, inv := range invariants {
+		if err := inv(app.BaseApp); err != nil {
+			panic(fmt.Errorf("invariant broken: %s", err))
+		}
+	}
+	end := time.Now()
+	diff := end.Sub(start)
+	app.BaseApp.Logger.With("module", "invariants").Info("Asserted all invariants", "duration", diff)
+}