Add a new script that checks if payer has balance to pay for tx

lib/go/templates/service_templates.go

@@ -38,6 +38,8 @@ const (
 	setExecutionMemoryWeighs  = "FlowServiceAccount/set_execution_memory_weights.cdc"
 	getExecutionMemoryLimit   = "FlowServiceAccount/scripts/get_execution_memory_limit.cdc"
 	setExecutionMemoryLimit   = "FlowServiceAccount/set_execution_memory_limit.cdc"
+
+	checkIfPayerHasSufficientBalance = "FlowServiceAccount/scripts/check_if_payer_has_sufficient_balance.cdc"
 )
 
 // FlowToken Templates
@@ -192,3 +194,9 @@ func GenerateGetExecutionMemoryLimit(env Environment) []byte {
 
 	return []byte(ReplaceAddresses(code, env))
 }
+
+func GenerateCheckIfPayerHasSufficientBalance(env Environment) []byte {
+	code := assets.MustAssetString(checkIfPayerHasSufficientBalance)
+
+	return []byte(ReplaceAddresses(code, env))
+}

lib/go/test/service_test.go

@@ -399,6 +399,21 @@ func TestContracts(t *testing.T) {
 
 	})
 
+	t.Run("Should check if payer has sufficient balance to execute tx", func(t *testing.T) {
+		// TODO: Is it better to set up a mock tx and test against it?
+
+		// TODO: What account should I use here?
+		account := cadence.NewAddress(flow.HexToAddress(env.FlowFeesAddress))
+		inclusionEffort := cadence.UFix64(1)
+		gasLimit := cadence.UFix64(99)
+
+		args := [][]byte{jsoncdc.MustEncode(account), jsoncdc.MustEncode(inclusionEffort), jsoncdc.MustEncode(gasLimit)}
+
+		result = executeScriptAndCheck(t, b, templates.GenerateCheckIfPayerHasSufficientBalance(env), args)
+		require.NotNil(t, result)
+		require.True(t, result.(cadence.Bool).ToGoValue().(bool))
+	})
+
 	// deploy the ServiceAccount contract
 	serviceAccountCode := contracts.FlowServiceAccount(
 		emulatorFTAddress,

transactions/FlowServiceAccount/scripts/check_if_payer_has_sufficient_balance.cdc

@@ -0,0 +1,8 @@
+import FlowFees from 0xFLOWFEESADDRESS
+
+pub fun main(payerAcct: Address, inclusionEffort: UFix64, maxExecutionEffort: UFix64): Bool {
+    let authAcct = getAuthAccount(payerAcct)
+    return FlowFees.verifyPayersBalanceForTransactionExecution(authAcct,
+        inclusionEffort: inclusionEffort,
+        maxExecutionEffort: maxExecutionEffort).canExecuteTransaction
+}