Provide Test Results

[CodeLenny]

Have each individual test publish the results of the run:

• success/failure
• run duration
• if failure, provide number of shrinks, counter-example, etc. See what JSVerify provides to shrinkResult

Store results in an array of TestResult objects:

class FailedTestError extends CustomError {
  constructor(res) {
    this.result = res;
  }
  get message() {
    return `shrunk ${this.result.shrinks} times, ...`;
  }
}

class TestResult {
  constructor() {
    this._work = Promise.defer();
  }
  success() {
    this.successful = true;
    this._work.resolve();
  }
  failure(shrinks, counterExample, ...) {
    this.successful = false;
    this.shrinks = shrinks;
    // ...
    this._work.reject(new FailedTestError(this));
  }
  get then() {
    return this._work.promise.then;
  }
  get catch() {
    return this._work.promise.catch;
  }
}

[CodeLenny]

TestDetails is being implemented in #1, and will probably include most of the needed properties for TestResult as drafted in the description.

Waiting for #1 before starting to prevent duplication.