@nomiclabs/hardhat-truffle4/src/type-extensions.ts

Truffle 4 Hardhat compatibility plugin

import { assert, expect } from "chai";
import "hardhat/types/artifacts";
import "hardhat/types/runtime";

declare module "hardhat/types/artifacts" {
  export interface Artifacts {
    require(name: string): any;
  }
}
declare module "hardhat/types/runtime" {
  type Describe = (
    description: string,
    definition: (accounts: string[]) => any
  ) => void;

  export interface HardhatRuntimeEnvironment {
    assert: typeof assert;
    expect: typeof expect;
    contract: Describe & Record<"only" | "skip", Describe>;
  }
}