Add test for new GetArbOSConfigAtHeight() method in ExecutionNode

This commit adds an integration test for the GetArbOSConfigAtHeight()
method on the Execution node that grabs the initial config, and
validates it, then updates the config and ensures that the new method
will fetch the updated config.

system_tests/espresso_arbos_test.go

@@ -0,0 +1,128 @@
+package arbtest
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"math/big"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/offchainlabs/nitro/arbutil"
+	"github.com/offchainlabs/nitro/solgen/go/precompilesgen"
+)
+
+func EspressoArbOSTestChainConfig() *params.ChainConfig {
+	return &params.ChainConfig{
+		ChainID:             big.NewInt(412346),
+		HomesteadBlock:      big.NewInt(0),
+		DAOForkBlock:        nil,
+		DAOForkSupport:      true,
+		EIP150Block:         big.NewInt(0),
+		EIP155Block:         big.NewInt(0),
+		EIP158Block:         big.NewInt(0),
+		ByzantiumBlock:      big.NewInt(0),
+		ConstantinopleBlock: big.NewInt(0),
+		PetersburgBlock:     big.NewInt(0),
+		IstanbulBlock:       big.NewInt(0),
+		MuirGlacierBlock:    big.NewInt(0),
+		BerlinBlock:         big.NewInt(0),
+		LondonBlock:         big.NewInt(0),
+		ArbitrumChainParams: EspressoTestChainParams(),
+		Clique: &params.CliqueConfig{
+			Period: 0,
+			Epoch:  0,
+		},
+	}
+}
+func EspressoTestChainParams() params.ArbitrumChainParams {
+	return params.ArbitrumChainParams{
+		EnableArbOS:               true,
+		AllowDebugPrecompiles:     true,
+		DataAvailabilityCommittee: false,
+		InitialArbOSVersion:       31,
+		InitialChainOwner:         common.Address{},
+		EnableEspresso: 		   false,
+	}
+}
+
+func waitForConfigUpdate(t *testing.T, ctx context.Context, builder *NodeBuilder) error{
+
+    return waitForWith(t, ctx, 120*time.Second, 1*time.Second, func() bool{
+      newArbOSConfig, err := builder.L2.ExecNode.GetArbOSConfigAtHeight(0)
+      Require(t, err)
+
+      if newArbOSConfig.ArbitrumChainParams.EnableEspresso != false{
+        return false
+      }
+      Require(t,err)
+      return true
+    })
+}
+
+func TestEspressoArbOSConfig(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	builder, cleanup := createL1AndL2Node(ctx, t)
+	defer cleanup()
+
+	err := waitForL1Node(t, ctx)
+	Require(t, err)
+
+	cleanEspresso := runEspresso(t, ctx)
+	defer cleanEspresso()
+
+	// wait for the builder
+	err = waitForEspressoNode(t, ctx)
+	Require(t, err)
+
+	l2Node := builder.L2
+
+	// Wait for the initial message
+	expected := arbutil.MessageIndex(1)
+	err = waitFor(t, ctx, func() bool {
+		msgCnt, err := l2Node.ConsensusNode.TxStreamer.GetMessageCount()
+		if err != nil {
+			panic(err)
+		}
+
+		validatedCnt := l2Node.ConsensusNode.BlockValidator.Validated(t)
+		return msgCnt >= expected && validatedCnt >= expected
+	})
+	Require(t, err)
+
+
+  initialArbOSConfig, err := builder.L2.ExecNode.GetArbOSConfigAtHeight(0)
+  Require(t,err)
+
+  //assert that espresso is initially enabled
+  if initialArbOSConfig.ArbitrumChainParams.EnableEspresso != true{
+    err = fmt.Errorf("Initial config should have EnableEspresso == true!")
+
+  } 
+  Require(t,err)
+
+  newArbOwner, err := precompilesgen.NewArbOwner(common.HexToAddress("0x070"), builder.L2.Client)
+  Require(t, err)
+
+  newArbDebug, err := precompilesgen.NewArbDebug(common.HexToAddress("0xff"), builder.L2.Client)
+  Require(t, err)
+
+  l2auth := builder.L2Info.GetDefaultTransactOpts("Owner", ctx)
+
+  _, err = newArbDebug.BecomeChainOwner(&l2auth)
+  Require(t, err)
+  chainConfig, err := json.Marshal(EspressoArbOSTestChainConfig())
+  Require(t, err)
+
+  chainConfigString := string(chainConfig)
+
+  _, err = newArbOwner.SetChainConfig(&l2auth, chainConfigString)
+  Require(t, err)
+  // check if chain config is updated TODO replace this with a wait for with to poll for some time potentially
+
+  waitForConfigUpdate(t, ctx, builder)
+}