vitest-marbles/src/vitest/custom-matchers.ts

Marble testing helpers library for RxJs and Jest

import { type MatchersObject } from '@vitest/expect';
import {type Assertion, type AsymmetricMatchersContaining } from 'vitest';
import { Marblizer } from '../marblizer';
import { SubscriptionLog, TestMessages } from '../rxjs/types';

function canMarblize(...messages: TestMessages[]) {
  return messages.every(message => message.filter(({ notification: { kind } }) => kind === 'N').every(isCharacter));
}

function isCharacter({ notification }: TestMessages[0]): boolean {
  const value = (notification as any).value;
  return (
    (typeof value === 'string' && value.length === 1) || (value !== undefined && JSON.stringify(value).length === 1)
  );
}

export const customTestMatchers: MatchersObject = {
  toBeNotifications(actual: TestMessages, expected: TestMessages) {
    let actualMarble: string | TestMessages = actual;
    let expectedMarble: string | TestMessages = expected;
    if (canMarblize(actual, expected)) {
      actualMarble = Marblizer.marblize(actual);
      expectedMarble = Marblizer.marblize(expected);
    }

    const pass = this.equals(actualMarble, expectedMarble);

    const message = pass
      ? () =>
        this.utils.matcherHint('.not.toBeNotifications') +
        '\n\n' +
        `Expected notifications to not be:\n` +
        `  ${this.utils.printExpected(expectedMarble)}\n` +
        `But got:\n` +
        `  ${this.utils.printReceived(actualMarble)}`
      : () => {
        const diffString = this.utils.diff(expectedMarble, actualMarble, {
          expand: true,
        });
        return (
          this.utils.matcherHint('.toBeNotifications') +
          '\n\n' +
          `Expected notifications to be:\n` +
          `  ${this.utils.printExpected(expectedMarble)}\n` +
          `But got:\n` +
          `  ${this.utils.printReceived(actualMarble)}` +
          (diffString ? `\n\nDifference:\n\n${diffString}` : '')
        );
      };

    return { message, pass };
  },

  toBeSubscriptions(actual: SubscriptionLog[], expected: SubscriptionLog[]) {
    const actualMarbleArray = Marblizer.marblizeSubscriptions(actual);
    const expectedMarbleArray = Marblizer.marblizeSubscriptions(expected);

    const pass = subscriptionsPass(actualMarbleArray, expectedMarbleArray);
    const message = pass
      ? () =>
        this.utils.matcherHint('.not.toHaveSubscriptions') +
        '\n\n' +
        `Expected observable to not have the following subscription points:\n` +
        `  ${this.utils.printExpected(expectedMarbleArray)}\n` +
        `But got:\n` +
        `  ${this.utils.printReceived(actualMarbleArray)}`
      : () => {
        const diffString = this.utils.diff(expectedMarbleArray, actualMarbleArray, {
          expand: true,
        });
        return (
          this.utils.matcherHint('.toHaveSubscriptions') +
          '\n\n' +
          `Expected observable to have the following subscription points:\n` +
          `  ${this.utils.printExpected(expectedMarbleArray)}\n` +
          `But got:\n` +
          `  ${this.utils.printReceived(actualMarbleArray)}` +
          (diffString ? `\n\nDifference:\n\n${diffString}` : '')
        );
      };

    return { message, pass };
  },

  toHaveEmptySubscriptions(actual: SubscriptionLog[] | undefined) {
    const pass = !(actual && actual.length > 0);
    let marbles: string[];
    if (actual && actual.length > 0) {
      marbles = Marblizer.marblizeSubscriptions(actual);
    }
    const message = pass
      ? () =>
        this.utils.matcherHint('.not.toHaveNoSubscriptions') +
        '\n\n' +
        `Expected observable to have at least one subscription point, but got nothing` +
        this.utils.printReceived('')
      : () =>
        this.utils.matcherHint('.toHaveNoSubscriptions') +
        '\n\n' +
        `Expected observable to have no subscription points\n` +
        `But got:\n` +
        `  ${this.utils.printReceived(marbles)}\n\n`;
    return { message, pass };
  },
};

function subscriptionsPass(actualMarbleArray: string[], expectedMarbleArray: string[]): boolean {
  if (actualMarbleArray.length !== expectedMarbleArray.length) {
    return false;
  }
  let pass = true;
  for (const actualMarble of actualMarbleArray) {
    if (!expectedMarbleArray.includes(actualMarble)) {
      pass = false;
      break;
    }
  }
  return pass;
}

interface VitestMarblesMatchers {
  toBeNotifications(notifications: TestMessages): void;

  toBeSubscriptions(subscriptions: SubscriptionLog[]): void;

  toHaveEmptySubscriptions(): void;
}

declare module 'vitest' {
  interface Assertion extends VitestMarblesMatchers {
  }

  interface AsymmetricMatchersContaining extends VitestMarblesMatchers {
  }
}

expect.extend(customTestMatchers);