test: add integration test for the rollback cmd (#1311)

* test the fixed rollback cmd

- check the rollback cmd works in integration tests

* Apply suggestions from code review

* upstream merged

* add changelog

Co-authored-by: Freddy Caceres <facs95@gmail.com>

tests/integration_tests/configs/broken-ethermintd.nix

@@ -0,0 +1,8 @@
+{ pkgs ? import ../../../nix { } }:
+let ethermintd = (pkgs.callPackage ../../../. { });
+in
+ethermintd.overrideAttrs (oldAttrs: {
+  patches = oldAttrs.patches or [ ] ++ [
+    ./broken-ethermintd.patch
+  ];
+})

tests/integration_tests/configs/broken-ethermintd.patch

@@ -0,0 +1,15 @@
+diff --git a/app/app.go b/app/app.go
+index 158bf7a3..a3b5718c 100644
+--- a/app/app.go
++++ b/app/app.go
+@@ -681,6 +681,10 @@ func (app *EthermintApp) BeginBlocker(ctx sdk.Context, req abci.RequestBeginBloc
+ 
+ // EndBlocker updates every end block
+ func (app *EthermintApp) EndBlocker(ctx sdk.Context, req abci.RequestEndBlock) abci.ResponseEndBlock {
++	if ctx.BlockHeight()%10 == 0 {
++		store := ctx.KVStore(app.keys["evm"])
++		store.Set([]byte("hello"), []byte("world"))
++	}
+ 	return app.mm.EndBlock(ctx, req)
+ }
+ 

tests/integration_tests/configs/rollback-test.jsonnet

@@ -0,0 +1,9 @@
+local config = import 'default.jsonnet';
+
+config {
+  'ethermint_9000-1'+: {
+    validators: super.validators + [{
+      name: 'fullnode',
+    }],
+  },
+}