// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License. See License.txt in the project root for license information.

import assert from "assert";

/**
 * Assert that the provided syncFunction throws an Error. If the expectedError is undefined, then
 * this function will just assert that an Error was thrown. If the expectedError is defined, then
 * this function will assert that the Error that was thrown is equal to the provided expectedError.
 * @param syncFunction The synchronous function that is expected to thrown an Error.
 * @param expectedError The Error that is expected to be thrown.
 */
export function throws(syncFunction: () => void, expectedError?: ((error: Error) => void) | Error): Error {
  let thrownError: Error | undefined;

  try {
    syncFunction();
  } catch (error) {
    thrownError = error;
  }

  if (!thrownError) {
    assert.throws(() => { });
  } else if (expectedError instanceof Error) {
    assert.deepStrictEqual(thrownError, expectedError);
  } else if (expectedError) {
    expectedError(thrownError);
  }

  return thrownError!;
}

/**
 * Assert that the provided asyncFunction throws an Error. If the expectedError is undefined, then
 * this function will just assert that an Error was thrown. If the expectedError is defined, then
 * this function will assert that the Error that was thrown is equal to the provided expectedError.
 * @param asyncFunction The asynchronous function that is expected to thrown an Error.
 * @param expectedError The Error that is expected to be thrown.
 */
export async function throwsAsync<T>(asyncFunction: (() => Promise<T>) | Promise<T>, expectedError?: ((error: Error) => void) | Error): Promise<Error> {
  let thrownError: Error | undefined;

  try {
    await (typeof asyncFunction === "function" ? asyncFunction() : asyncFunction);
  } catch (error) {
    thrownError = error;
  }

  if (!thrownError) {
    assert.throws(() => { });
  } else if (expectedError instanceof Error) {
    assert.deepStrictEqual(thrownError, expectedError);
  } else if (expectedError) {
    expectedError(thrownError);
  }

  return thrownError!;
}