readFile_mock.js

import * as assert from "assert";
import * as fs from "fs";

// Original functions
const readFile = fs.readFile;

teardown(function() {
  (fs as any).readFile = readFile;
});

test("#load: Should reject when readFile returns an error @unit", function(done) {
  const readFile = function(path: string, cb) {
    assert.equal(path, "pathtofile");
    const error: NodeJS.ErrnoException = new Error("could not read from fs");
    return cb(error, Buffer.from(""));
  };
  (fs as any).readFile = readFile;

  const coverage = new Coverage(
    fakeConfig,
  );
});