Fix the calculation for estimated gas price

.changeset/serious-yaks-deny.md

@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+**Celo:** Added support for gas price estimation on both Celo L1 and Celo L2.

src/celo/fees.test.ts

@@ -26,17 +26,29 @@ 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 '15057755162'
-      if (request.method === 'eth_maxPriorityFeePerGas') return '602286'
+      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,
@@ -45,10 +57,63 @@ describe('celo/fees', () => {
       },
     } as any)
 
+    // For celo L1 the fees maxFeePerGas is calculated as `baseFee + maxPriorityFeePerGas`, the multiply method is not used.
     expect(fees).toMatchInlineSnapshot(`
         {
-          "maxFeePerGas": 22587235029n,
-          "maxPriorityFeePerGas": 602286n,
+          "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

@@ -1,3 +1,4 @@
+import { getCode } from '../actions/public/getCode.js'
 import type { Client } from '../clients/createClient.js'
 import type {
   Address,
@@ -22,19 +23,23 @@ export const fees: ChainFees<typeof formatters> = {
   ) => {
     if (!params.request?.feeCurrency) return null
 
-    const [maxFeePerGas, maxPriorityFeePerGas] = await Promise.all([
+    const [gasPrice, maxPriorityFeePerGas, cel2] = await Promise.all([
       estimateFeePerGasInFeeCurrency(params.client, params.request.feeCurrency),
       estimateMaxPriorityFeePerGasInFeeCurrency(
         params.client,
         params.request.feeCurrency,
       ),
+      isCel2(params.client),
     ])
 
-    const suggestedMaxFeePerGas =
-      params.multiply(maxFeePerGas) + maxPriorityFeePerGas
+    const maxFeePerGas = cel2
+      ? // eth_gasPrice for cel2 returns baseFeePerGas + maxPriorityFeePerGas
+        params.multiply(gasPrice - maxPriorityFeePerGas) + maxPriorityFeePerGas
+      : // eth_gasPrice for Celo L1 returns (baseFeePerGas * multiplier), where the multiplier is 2 by default.
+        gasPrice + maxPriorityFeePerGas
 
     return {
-      maxFeePerGas: suggestedMaxFeePerGas,
+      maxFeePerGas,
       maxPriorityFeePerGas,
     }
   },
@@ -92,3 +97,9 @@ async function estimateMaxPriorityFeePerGasInFeeCurrency(
     })
   return BigInt(feesPerGas)
 }
+
+async function isCel2(client: Client) {
+  const proxyAdminAddress = '0x4200000000000000000000000000000000000018'
+  const code = await getCode(client, { address: proxyAdminAddress })
+  return Boolean(code)
+}

src/celo/sendTransaction.test.ts

@@ -99,7 +99,7 @@ describe('sendTransaction()', () => {
     expect(transportRequestMock).toHaveBeenLastCalledWith({
       method: 'eth_sendRawTransaction',
       params: [
-        '0x7bf87f82a4ec80830930ae8504350cec000194f39fd6e51aad88f6f4ce6ab8827279cfffb922660180c0940000000000000000000000000000000000000fee80a0b61a83b7fe73e24f223f563447cdb69f6dedc7f7f7b2acc4e41f2e57143ccd57a03ce0bcc81c026ff0eb17274940748e23250fe988f71370eba1e59e43557835b3',
+        '0x7bf87f82a4ec80830930ae8503818c4cc80194f39fd6e51aad88f6f4ce6ab8827279cfffb922660180c0940000000000000000000000000000000000000fee01a07dbc07e3ed73e889b085f29f2b4a1e794d578307199b5a677071a204328837a0a02da0ba218d0ab8164010f3c0efa7f84f4df6d879a242dc5110248e7014df75dc',
       ],
     })
   })