fix: minimum fee of 0.1 gwei on optimism

src/hooks/__tests__/useGasPrice.test.ts

@@ -1,15 +1,16 @@
 import { BigNumber } from 'ethers'
 import { act, renderHook } from '@/tests/test-utils'
 import useGasPrice from '@/hooks/useGasPrice'
+import { useCurrentChain } from '../useChains'
 
 // mock useWeb3Readonly
 jest.mock('../wallets/web3', () => {
   const provider = {
     getFeeData: jest.fn(() =>
       Promise.resolve({
         gasPrice: undefined,
-        maxFeePerGas: BigNumber.from('0x956e'),
-        maxPriorityFeePerGas: BigNumber.from('0x136f'),
+        maxFeePerGas: BigNumber.from('0x956e'), //38254
+        maxPriorityFeePerGas: BigNumber.from('0x136f'), //4975
       }),
     ),
   }
@@ -19,30 +20,29 @@ jest.mock('../wallets/web3', () => {
 })
 
 // Mock useCurrentChain
+const currentChain = {
+  chainId: '4',
+  gasPrice: [
+    {
+      type: 'ORACLE',
+      uri: 'https://api.etherscan.io/api?module=gastracker&action=gasoracle',
+      gasParameter: 'FastGasPrice',
+      gweiFactor: '1000000000.000000000',
+    },
+    {
+      type: 'ORACLE',
+      uri: 'https://ethgasstation.info/json/ethgasAPI.json',
+      gasParameter: 'fast',
+      gweiFactor: '200000000.000000000',
+    },
+    {
+      type: 'FIXED',
+      weiValue: '24000000000',
+    },
+  ],
+  features: ['EIP1559'],
+}
 jest.mock('@/hooks/useChains', () => {
-  const currentChain = {
-    chainId: '4',
-    gasPrice: [
-      {
-        type: 'ORACLE',
-        uri: 'https://api.etherscan.io/api?module=gastracker&action=gasoracle',
-        gasParameter: 'FastGasPrice',
-        gweiFactor: '1000000000.000000000',
-      },
-      {
-        type: 'ORACLE',
-        uri: 'https://ethgasstation.info/json/ethgasAPI.json',
-        gasParameter: 'fast',
-        gweiFactor: '200000000.000000000',
-      },
-      {
-        type: 'FIXED',
-        weiValue: '24000000000',
-      },
-    ],
-    features: ['EIP1559'],
-  }
-
   return {
     useCurrentChain: jest.fn(() => currentChain),
   }
@@ -52,6 +52,7 @@ describe('useGasPrice', () => {
   beforeEach(() => {
     jest.useFakeTimers()
     jest.clearAllMocks()
+    ;(useCurrentChain as jest.Mock).mockReturnValue(currentChain)
   })
 
   it('should return the fetched gas price from the first oracle', async () => {
@@ -170,6 +171,50 @@ describe('useGasPrice', () => {
     expect(result.current[0]?.maxPriorityFeePerGas?.toString()).toEqual('4975')
   })
 
+  it("should use the previous block's fee data if there are no oracles", async () => {
+    ;(useCurrentChain as jest.Mock).mockReturnValue({
+      chainId: '1',
+      gasPrice: [],
+      features: ['EIP1559'],
+    })
+
+    const { result } = renderHook(() => useGasPrice())
+
+    await act(async () => {
+      await Promise.resolve()
+    })
+    // assert the hook is not loading
+    expect(result.current[2]).toBe(false)
+
+    // assert gas price from provider
+    expect(result.current[0]?.maxFeePerGas?.toString()).toBe('38254')
+
+    // assert priority fee from provider
+    expect(result.current[0]?.maxPriorityFeePerGas?.toString()).toBe('4975')
+  })
+
+  it('should use a minimum max fee per gas of 0.1 gwei on optimism', async () => {
+    ;(useCurrentChain as jest.Mock).mockReturnValue({
+      chainId: '10',
+      gasPrice: [],
+      features: ['EIP1559'],
+    })
+
+    const { result } = renderHook(() => useGasPrice())
+
+    await act(async () => {
+      await Promise.resolve()
+    })
+    // assert the hook is not loading
+    expect(result.current[2]).toBe(false)
+
+    // assert gas price as minimum of 0.1 gwei
+    expect(result.current[0]?.maxFeePerGas?.toString()).toBe('100000000')
+
+    // assert priority fee from provider
+    expect(result.current[0]?.maxPriorityFeePerGas?.toString()).toBe('4975')
+  })
+
   it('should keep the previous gas price if the hook re-renders', async () => {
     // Mock fetch
     Object.defineProperty(window, 'fetch', {

src/hooks/useGasPrice.ts

@@ -8,6 +8,12 @@ import { useWeb3ReadOnly } from '../hooks/wallets/web3'
 import { Errors, logError } from '@/services/exceptions'
 import { FEATURES, hasFeature } from '@/utils/chains'
 import { asError } from '@/services/exceptions/utils'
+import { adjustGasEstimationForChain } from '@/utils/gas'
+
+export type EstimatedGasPrice = {
+  maxFeePerGas: BigNumber | undefined
+  maxPriorityFeePerGas: BigNumber | undefined
+}
 
 // Update gas fees every 20 seconds
 const REFRESH_DELAY = 20e3
@@ -53,10 +59,7 @@ const getGasPrice = async (gasPriceConfigs: GasPrice): Promise<BigNumber | undef
   }
 }
 
-const useGasPrice = (): AsyncResult<{
-  maxFeePerGas: BigNumber | undefined
-  maxPriorityFeePerGas: BigNumber | undefined
-}> => {
+const useGasPrice = (): AsyncResult<EstimatedGasPrice> => {
   const chain = useCurrentChain()
   const gasPriceConfigs = chain?.gasPrice
   const [counter] = useIntervalCounter(REFRESH_DELAY)
@@ -77,10 +80,12 @@ const useGasPrice = (): AsyncResult<{
       const maxFee = gasPrice || (isEIP1559 ? feeData?.maxFeePerGas : feeData?.gasPrice) || undefined
       const maxPrioFee = (isEIP1559 && feeData?.maxPriorityFeePerGas) || undefined
 
-      return {
+      const gasEstimation = {
         maxFeePerGas: maxFee,
         maxPriorityFeePerGas: maxPrioFee,
       }
+
+      return adjustGasEstimationForChain(gasEstimation, chain?.chainId)
     },
     // eslint-disable-next-line react-hooks/exhaustive-deps
     [gasPriceConfigs, provider, counter, isEIP1559],

src/utils/gas.ts

@@ -0,0 +1,19 @@
+import chains from '@/config/chains'
+import type { EstimatedGasPrice } from '@/hooks/useGasPrice'
+import { BigNumber } from 'ethers'
+
+const OPTIMISM_MINIMUM_BASE_FEE_WEI = BigNumber.from(100000000)
+
+export const adjustGasEstimationForChain = (gas: EstimatedGasPrice, chainId: string | undefined) => {
+  if (chainId === chains.oeth) {
+    // On Optimism we lower bound the base fee to 0.1 gwei because the base fee can spike quite fast
+    return {
+      ...gas,
+      maxFeePerGas: gas.maxFeePerGas?.lt(OPTIMISM_MINIMUM_BASE_FEE_WEI)
+        ? OPTIMISM_MINIMUM_BASE_FEE_WEI
+        : gas.maxFeePerGas,
+    }
+  }
+
+  return gas
+}