metamask-extension/test/unit/app/nodeify-test.js

import assert from 'assert';
import nodeify from '../../../app/scripts/lib/nodeify';

describe('nodeify', function () {
  const obj = {
    foo: 'bar',
    promiseFunc(a) {
      const solution = this.foo + a;
      return Promise.resolve(solution);
    },
  };

  it('should retain original context', function (done) {
    const nodified = nodeify(obj.promiseFunc, obj);
    nodified('baz', (err, res) => {
      if (!err) {
        assert.equal(res, 'barbaz');
        done();
        return;
      }

      done(new Error(err.toString()));
    });
  });

  it('no callback - should allow the last argument to not be a function', function (done) {
    const nodified = nodeify(obj.promiseFunc, obj);
    try {
      nodified('baz');
      done();
    } catch (err) {
      done(
        new Error(
          'should not have thrown if the last argument is not a function',
        ),
      );
    }
  });

  it('sync functions - returns value', function (done) {
    const nodified = nodeify(() => 42);
    try {
      nodified((err, result) => {
        if (err) {
          done(new Error(`should not have thrown any error: ${err.message}`));
          return;
        }
        assert.equal(42, result, 'got expected result');
      });
      done();
    } catch (err) {
      done(new Error(`should not have thrown any error: ${err.message}`));
    }
  });

  it('sync functions - handles errors', function (done) {
    const nodified = nodeify(() => {
      throw new Error('boom!');
    });
    try {
      nodified((err, result) => {
        if (result) {
          done(new Error('should not have returned any result'));
          return;
        }
        assert.ok(err, 'got expected error');
        assert.ok(err.message.includes('boom!'), 'got expected error message');
      });
      done();
    } catch (err) {
      done(new Error(`should not have thrown any error: ${err.message}`));
    }
  });
});