toMatchScreenshot( received, mismatchTolerance, source ) {
      const pass = Number( received ) === 0;
      return expectReturn( pass,
        `[${ source }] expected to satisfy mismatch tolerance of ${ mismatchTolerance }`,
        `[${ source }] expected `
          + `not to satisfy mismatch tolerance of ${ mismatchTolerance }` );
    }
Assert value is truthy
@param {Boolean} received
@param {*} mismatchTolerance
@param {String} source
@returns {Object}