Add Cadence transaction batching EVM calls

README.md

@@ -1,5 +1,14 @@
-### Batched Cadence EVM Execution Example
+# Batched Cadence EVM Execution Example
 
 > This repo contains an example of how to batch EVM execution on Flow using Cadence.
 
-:building_construction: WIP 
+:building_construction: Currently work in progress.
+
+## Deployments
+
+The relevant contracts can be found at the following addresses on Flow Testnet:
+
+|Contract|Address|
+|---|---|
+|`MaybeMintERC72`|[`0xdbC43Ba45381e02825b14322cDdd15eC4B3164E6`](https://evm-testnet.flowscan.io/address/0xdbc43ba45381e02825b14322cddd15ec4b3164e6?tab=contract_code)|
+|`WFLOW`|[`0xd3bF53DAC106A0290B0483EcBC89d40FcC961f3e`](https://evm-testnet.flowscan.io/token/0xd3bF53DAC106A0290B0483EcBC89d40FcC961f3e?tab=contract_code)|

cadence/tests/transactions/create_coa.cdc

@@ -0,0 +1,51 @@
+import "EVM"
+import "FungibleToken"
+import "FlowToken"
+
+/// Configures a COA in the signer's Flow account, funding with the specified amount. If the COA already exists, the
+/// transaction reverts.
+///
+transaction(amount: UFix64) {
+    let coa: &EVM.CadenceOwnedAccount
+    let sentVault: @FlowToken.Vault
+
+    prepare(signer: auth(BorrowValue, IssueStorageCapabilityController, PublishCapability, SaveValue, UnpublishCapability) &Account) {
+        let storagePath = /storage/evm
+        let publicPath = /public/evm
+
+        // Revert if the CadenceOwnedAccount already exists
+        if signer.storage.type(at: storagePath) != nil {
+            panic("Storage collision - Resource already stored at path=".concat(storagePath.toString()))
+        }
+
+        // Configure the CadenceOwnedAccount
+        signer.storage.save<@EVM.CadenceOwnedAccount>(<-EVM.createCadenceOwnedAccount(), to: storagePath)
+        let addressableCap = signer.capabilities.storage.issue<&EVM.CadenceOwnedAccount>(storagePath)
+        signer.capabilities.unpublish(publicPath)
+        signer.capabilities.publish(addressableCap, at: publicPath)
+
+        // Reference the CadeceOwnedAccount
+        self.coa = signer.storage.borrow<auth(EVM.Owner) &EVM.CadenceOwnedAccount>(from: /storage/evm)
+            ?? panic("Missing or mis-typed CadenceOwnedAccount at /storage/evm")
+
+        // Withdraw the amount from the signer's FlowToken vault
+        let vaultRef = signer.storage.borrow<auth(FungibleToken.Withdraw) &FlowToken.Vault>(
+                from: /storage/flowTokenVault
+            ) ?? panic("Could not borrow reference to the owner's Vault!")
+        self.sentVault <- vaultRef.withdraw(amount: amount) as! @FlowToken.Vault
+    }
+
+    pre {
+        self.sentVault.balance == amount:
+        "Expected amount =".concat(amount.toString()).concat(" but sentVault.balance=").concat(self.sentVault.balance.toString())
+    }
+
+    execute {
+        // Deposit the amount into the CadenceOwnedAccount if the balance is greater than zero
+        if self.sentVault.balance > 0.0 {
+            self.coa.deposit(from: <-self.sentVault)
+        } else {
+            destroy self.sentVault
+        }
+    }
+}

cadence/tests/transactions/deploy.cdc

@@ -0,0 +1,56 @@
+import "FungibleToken"
+import "FlowToken"
+
+import "EVM"
+
+/// Deploys a compiled solidity contract from bytecode to the EVM, with the signer's COA as the deployer
+///
+transaction(bytecode: String, gasLimit: UInt64, value: UFix64) {
+
+    let coa: auth(EVM.Deploy) &EVM.CadenceOwnedAccount
+    var sentVault: @FlowToken.Vault?
+
+    prepare(signer: auth(BorrowValue) &Account) {
+
+        let storagePath = StoragePath(identifier: "evm")!
+        self.coa = signer.storage.borrow<auth(EVM.Deploy) &EVM.CadenceOwnedAccount>(from: storagePath)
+            ?? panic("Could not borrow reference to the signer's bridged account")
+
+        // Rebalance Flow across VMs if there is not enough Flow in the EVM account to cover the value
+        let evmFlowBalance: UFix64 = self.coa.balance().inFLOW()
+        if self.coa.balance().inFLOW() < value {
+            let withdrawAmount: UFix64 = value - evmFlowBalance
+            let vaultRef = signer.storage.borrow<auth(FungibleToken.Withdraw) &FlowToken.Vault>(
+                    from: /storage/flowTokenVault
+                ) ?? panic("Could not borrow reference to the owner's Vault!")
+
+            self.sentVault <- vaultRef.withdraw(amount: withdrawAmount) as! @FlowToken.Vault
+        } else {
+            self.sentVault <- nil
+        }
+    }
+
+    execute {
+
+        // Deposit Flow into the EVM account if necessary otherwise destroy the sent Vault
+        if self.sentVault != nil {
+            self.coa.deposit(from: <-self.sentVault!)
+        } else {
+            destroy self.sentVault
+        }
+
+        let valueBalance = EVM.Balance(attoflow: 0)
+        valueBalance.setFLOW(flow: value)
+        // Finally deploy the contract
+        let evmResult = self.coa.deploy(
+           code: bytecode.decodeHex(),
+           gasLimit: gasLimit,
+           value: valueBalance
+        )
+        assert(
+            evmResult.status == EVM.Status.successful && evmResult.deployedContract != nil,
+            message: "EVM deployment failed with error code: ".concat(evmResult.errorCode.toString())
+                .concat(" and message: ").concat(evmResult.errorMessage)
+        )
+    }
+}

cadence/tests/transactions/move_block.cdc

@@ -0,0 +1,19 @@
+import "EVM"
+
+transaction {
+    let coa: auth(EVM.Call) &EVM.CadenceOwnedAccount
+    prepare(signer: auth(BorrowValue) &Account) {
+        self.coa = signer.storage.borrow<auth(EVM.Call) &EVM.CadenceOwnedAccount>(from: /storage/evm)
+            ?? panic("A CadenceOwnedAccount (COA) Resource could not be found at path /storage/evm")
+    }
+
+    execute {
+        let res = self.coa.call(
+            to: self.coa.address(),
+            data: [],
+            gasLimit: 15_000_000,
+            value: EVM.Balance(attoflow: 0)
+        )
+        assert(res.status == EVM.Status.successful, message: "Empty EVM call failed")
+    }
+}

cadence/tests/wrap_and_mint_tests.cdc

@@ -0,0 +1,101 @@
+import Test
+import BlockchainHelpers
+import "test_helpers.cdc"
+
+import "EVM"
+
+access(all) let serviceAccount = Test.serviceAccount()
+
+access(all) var coaAddress: String = ""
+access(all) var wflowAddress: String = ""
+access(all) var erc721Address: String = ""
+
+access(all)
+fun setup() {
+    // Create & fund a CadenceOwnedAccount
+    let coaRes = executeTransaction(
+        "./transactions/create_coa.cdc",
+        [100.0],
+        serviceAccount
+    )
+    Test.expect(coaRes, Test.beSucceeded())
+
+    // Extract COA address from event
+    let coaEvts = Test.eventsOfType(Type<EVM.CadenceOwnedAccountCreated>())
+    let coaEvt = coaEvts[0] as! EVM.CadenceOwnedAccountCreated
+    coaAddress = coaEvt.address
+
+    // Deploy WFLOW
+    let wflowDeployRes = executeTransaction(
+        "./transactions/deploy.cdc",
+        [getWFLOWBytecode(), UInt64(15_000_000), 0.0],
+        serviceAccount
+    )
+    Test.expect(wflowDeployRes, Test.beSucceeded())
+
+    // Extract WFLOW address from event
+    var txnExecEvts = Test.eventsOfType(Type<EVM.TransactionExecuted>())
+    let wflowEvt = txnExecEvts[2] as! EVM.TransactionExecuted
+    wflowAddress = wflowEvt.contractAddress
+
+    // Deploy ERC721
+    let constructorArgs = [
+        "Maybe Mint ERC721",
+        "MAYBE",
+        EVM.addressFromString(wflowAddress),
+        UInt256(1_000_000_000_000_000_000),
+        EVM.addressFromString(coaAddress)
+    ]
+    // Encode constructor args as ABI and then as hex
+    let argsBytecode = String.encodeHex(EVM.encodeABI(
+        constructorArgs
+    ))
+    // Append the encoded constructor args to the compiled bytecode
+    let finalBytecode = String.join([getERC721Bytecode(), argsBytecode], separator: "")
+    let erc721DeployRes = executeTransaction(
+        "./transactions/deploy.cdc",
+        [finalBytecode, UInt64(15_000_000), 0.0],
+        serviceAccount
+    )
+    Test.expect(erc721DeployRes, Test.beSucceeded())
+
+    // Extract ERC721 address from event
+    txnExecEvts = Test.eventsOfType(Type<EVM.TransactionExecuted>())
+    let erc721Evt = txnExecEvts[3] as! EVM.TransactionExecuted
+    erc721Address = erc721Evt.contractAddress
+}
+
+access(all)
+fun testWrapAndMintSucceeds() {
+    let user = Test.createAccount()
+    mintFlow(to: user, amount: 10.0)
+
+    // Executes the wrap_and_mint.cdc transaction
+    // - Creates a COA
+    // - Funds the COA with FLOW to cover mint cost
+    // - Wraps FLOW as WFLOW
+    // - Approves ERC721 contract to mint
+    // - Mints ERC721 <- may fail so we retry here until success (can't mock CadenceArch calls in Cadence tests atm)
+    wrapAndMintUntilSuccess(iter: 5, signer: user, wflow: wflowAddress, erc721: erc721Address)
+}
+
+access(all)
+fun wrapAndMintUntilSuccess(iter: Int, signer: Test.TestAccount, wflow: String, erc721: String) {
+    var i = 0
+    var success = false
+    while i < iter {
+        let res = executeTransaction(
+            "../transactions/bundled/wrap_and_mint.cdc",
+            [wflow, erc721],
+            signer
+        )
+        if res.error == nil {
+            success = true
+            break
+        } else {
+            i = i + 1
+            moveBlock()
+        }
+    }
+    Test.assert(success)
+}