External Plugin

This is a third-party plugin. Please report issues in its Github Repository(opens new window)

# buidler-mocks

buidler-mocks is a utility package that can generate mock Solidity contracts for use within tests. buidler-mocks hooks into buidler's internal virtual machine so that mock contract functions can be written entirely in JavaScript.

# Simple Example

import { ethers } from '@nomiclabs/buidler'
import { getMockContract } from '@eth-optimism/buidler-mocks'

const [signer] = await ethers.getSigners()
const myMockContract = await getMockContract(
      functionName: 'myFunction',
      inputTypes: ['address', 'string memory'],
      outputTypes: ['uint256'],
      returnValues: (paramA: string, paramB: string) => {
        if (paramA === '0x0000000000000000000000000000000000000000') {
          return [1234]
        } else if (paramB === 'Hello!') {
          return [5678]
        } else {
          return [12345678]


# MockContractFunction

# Interface

interface MockContractFunction {
  functionName: string
  inputTypes?: string[]
  outputTypes?: string[]
  returnValues?: any[] | ((...params: any[]) => any[])

# Description

MockContractFunction is the interface used to define functions for your mock contract object.

# Properties

  • functionName: Name for the function, will be used when the Solidity code for your contract is generated.
  • inputTypes: Input types to the function (e.g., array of address or string memory).
  • outputTypes: Output types returned by the function (same format as input types).
  • returnValues: Values to be returned by the function. Either a fixed array of values, or a function that returns an array. Number of elements returned must match the number of output types.

# MockContract

# Interface

interface MockContract extends Contract {
  getCallCount: (functionName: string) => number
  getCallData: (functionName: string, callIndex: number) => any[]
  setReturnValues: (functionName: string, returnValues: any[] | ((...params: any[]) => any[])) => void

# Description

MockContract is a type that extends the ethers.Contract object. It introduces several utility methods that can be used to access interactions with your mock contract.

# Properties

  • getCallCount: Returns the number of times a particular function was called.
  • getCallData: Returns the calldata for a specific call to a given function.
  • setReturnValues: Replaces the return values for a given function.

# getMockContract

# Function Signature

const getMockContract = async (
  spec: MockContractFunction[] | Contract | ContractFactory,
  signer: Signer,
  compiler?: SolidityCompiler
): Promise<MockContract>

# Description

Generates and deploys a new MockContract instance.

# Inputs

  • spec: Specification for the mock contract. Can either be an array of MockContractFuction objects, an ethers.Contract object, or an ethers.ContractFactory object.
  • signer: ethers.Signer to use to deploy the mock contract.
  • compiler: Optional solc object to compile with. Otherwise will use the current buidler compiler within your project.

# Outputs

  • MockContract: Deployed MockContract instance.