Fix the calculation for estimated gas price

.changeset/great-spies-march.md

@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Fixed Celo maxFeePerGas calculation for fee currency transactions.

src/celo/fees.test.ts

@@ -26,28 +26,94 @@ describe('celo/fees', () => {
     expect(requestMock).not.toHaveBeenCalled()
   })
 
-  test('calls the client when feeCurrency is provided', async () => {
+  test('calls the client when feeCurrency is provided celo L1', async () => {
     const requestMock = vi.spyOn(client, 'request')
+
+    const baseFee = 15057755162n
+    const priorityFee = 602286n
+
+    expect(celo.fees.estimateFeesPerGas).toBeTypeOf('function')
+
+    // The check to determine if the chain is L1 or L2 is done by checking to
+    // see if there is code at the proxy admin address (by calling
+    // eth_getCode), if there is code then the chain is considered to be L2. A
+    // response of '0x' as used here is what is returned when there is no code
+    // at the address.
+
     // @ts-ignore
     requestMock.mockImplementation((request) => {
-      if (request.method === 'eth_gasPrice') return '11619349802'
-      if (request.method === 'eth_maxPriorityFeePerGas') return '2323869960'
+      if (request.method === 'eth_gasPrice') return baseFee.toString()
+      if (request.method === 'eth_maxPriorityFeePerGas')
+        return priorityFee.toString()
+      if (request.method === 'eth_getCode') return '0x'
       return
     })
 
-    expect(celo.fees.estimateFeesPerGas).toBeTypeOf('function')
-
     const fees = await celoestimateFeesPerGasFn({
       client,
+      multiply: (value: bigint) => (value * 150n) / 100n,
       request: {
         feeCurrency: '0xfee',
       },
     } as any)
 
+    // For celo L1 the fees maxFeePerGas is calculated as `baseFee + maxPriorityFeePerGas`, the multiply method is not used.
     expect(fees).toMatchInlineSnapshot(`
         {
-          "maxFeePerGas": 11619349802n,
-          "maxPriorityFeePerGas": 2323869960n,
+          "maxFeePerGas": ${baseFee + priorityFee}n,
+          "maxPriorityFeePerGas": ${priorityFee}n,
+        }
+      `)
+    expect(requestMock).toHaveBeenCalledWith({
+      method: 'eth_maxPriorityFeePerGas',
+      params: ['0xfee'],
+    })
+    expect(requestMock).toHaveBeenCalledWith({
+      method: 'eth_gasPrice',
+      params: ['0xfee'],
+    })
+  })
+
+  test('calls the client when feeCurrency is provided celo L2', async () => {
+    const requestMock = vi.spyOn(client, 'request')
+
+    const baseFee = 15057755162n
+    const priorityFee = 602286n
+
+    expect(celo.fees.estimateFeesPerGas).toBeTypeOf('function')
+
+    // The check to determine if the chain is L1 or L2 is done by checking to
+    // see if there is code at the proxy admin address (by calling
+    // eth_getCode), if there is code then the chain is considered to be L2. A
+    // response longer than '0x' as used here is what is returned when there is
+    // code at the address.
+
+    // @ts-ignore
+    requestMock.mockImplementation((request) => {
+      if (request.method === 'eth_gasPrice')
+        return (baseFee + priorityFee).toString()
+      if (request.method === 'eth_maxPriorityFeePerGas')
+        return priorityFee.toString()
+      if (request.method === 'eth_getCode') return '0x00400400404040404040404'
+      return
+    })
+
+    const multiply = (value: bigint) => (value * 150n) / 100n
+    const feesCeloL1 = await celoestimateFeesPerGasFn({
+      client,
+      multiply: multiply,
+      request: {
+        feeCurrency: '0xfee',
+      },
+    } as any)
+
+    // For Celo L2 the fees maxFeePerGas is calculated as the following where
+    // multiply is the method passed to celoestimateFeesPerGasFn:
+    //    `multiply(baseFeePerGas - maxPriorityFeePerGas) + maxPriorityFeePerGas`.
+    expect(feesCeloL1).toMatchInlineSnapshot(`
+        {
+          "maxFeePerGas": ${multiply(baseFee) + priorityFee}n,
+          "maxPriorityFeePerGas": ${priorityFee}n,
         }
       `)
     expect(requestMock).toHaveBeenCalledWith({

src/celo/fees.ts

@@ -7,6 +7,27 @@ import type {
 } from '../index.js'
 import type { formatters } from './formatters.js'
 
+type RequestGetCodeParams = {
+  Method: 'eth_getCode'
+  Parameters: [Address, 'latest']
+  ReturnType: Hex
+}
+/*
+ * This checks if we're in L2 context, it's a port of the technique used in
+ * https://github.com/celo-org/celo-monorepo/blob/da9b4955c1fdc8631980dc4adf9b05e0524fc228/packages/protocol/contracts-0.8/common/IsL2Check.sol#L17
+ */
+const isCel2 = async (client: Client) => {
+  const proxyAdminAddress = '0x4200000000000000000000000000000000000018'
+  const code = await client.request<RequestGetCodeParams>({
+    method: 'eth_getCode',
+    params: [proxyAdminAddress, 'latest'],
+  })
+  if (typeof code === 'string') {
+    return code !== '0x' && code.length > 2
+  }
+  return false
+}
+
 export const fees: ChainFees<typeof formatters> = {
   /*
    * Estimates the fees per gas for a transaction.
@@ -22,16 +43,26 @@ export const fees: ChainFees<typeof formatters> = {
   ) => {
     if (!params.request?.feeCurrency) return null
 
-    const [maxFeePerGas, maxPriorityFeePerGas] = await Promise.all([
+    const [gasPrice, maxPriorityFeePerGas] = await Promise.all([
       estimateFeePerGasInFeeCurrency(params.client, params.request.feeCurrency),
       estimateMaxPriorityFeePerGasInFeeCurrency(
         params.client,
         params.request.feeCurrency,
       ),
     ])
 
+    let maxFeePerGas: bigint
+    if (await isCel2(params.client)) {
+      // eth_gasPrice for cel2 returns baseFeePerGas + maxPriorityFeePerGas
+      maxFeePerGas =
+        params.multiply(gasPrice - maxPriorityFeePerGas) + maxPriorityFeePerGas
+    } else {
+      // eth_gasPrice for Celo L1 returns (baseFeePerGas * multiplier), where the multiplier is 2 by default.
+      maxFeePerGas = gasPrice + maxPriorityFeePerGas
+    }
+
     return {
-      maxFeePerGas,
+      maxFeePerGas: maxFeePerGas,
       maxPriorityFeePerGas,
     }
   },

src/celo/sendTransaction.test.ts

@@ -29,14 +29,14 @@ describe('sendTransaction()', () => {
     }
 
     if (request.method === 'eth_maxPriorityFeePerGas') {
-      return 1n
+      return 602286n
     }
 
     if (
       request.method === 'eth_gasPrice' &&
       (request.params as string[])[0] === feeCurrencyAddress
     ) {
-      return 2n
+      return 15057755162n
     }
 
     if (request.method === 'eth_estimateGas') {
@@ -99,7 +99,7 @@ describe('sendTransaction()', () => {
     expect(transportRequestMock).toHaveBeenLastCalledWith({
       method: 'eth_sendRawTransaction',
       params: [
-        '0x7bf87782a4ec8001020194f39fd6e51aad88f6f4ce6ab8827279cfffb922660180c0940000000000000000000000000000000000000fee80a0a3163f9ff91200f4c8000f0217d85d16c329c2f38d48a7b4b70119989e475e57a0555fd5b2a6eac95426e33cd07ca5fec121ad46194611a013001f76bbc4b33136',
+        '0x7bf87f82a4ec80830930ae8503818c4cc80194f39fd6e51aad88f6f4ce6ab8827279cfffb922660180c0940000000000000000000000000000000000000fee01a07dbc07e3ed73e889b085f29f2b4a1e794d578307199b5a677071a204328837a0a02da0ba218d0ab8164010f3c0efa7f84f4df6d879a242dc5110248e7014df75dc',
       ],
     })
   })