logger/tests/Logger.test.ts

import { describe, it, expect, beforeEach, vi, type Mock } from 'bun:test';
import Logger from '../src/Logger';
import { LoggingLevel } from '../src/level/LoggingLevel';
import Threshold from '../src/level/Threshold';
import type IAppender from '../src/appenders/IAppender';

describe('Logger', () => {
  let mockAppender: IAppender;
  let threshold: Threshold;
  let logger: Logger;

  beforeEach(() => {
    mockAppender = {
      log: vi.fn(),
    };

    threshold = new Threshold(LoggingLevel.Info);
    logger = new Logger('test-category', threshold, new Set([mockAppender]));
  });

  describe('threshold filtering', () => {
    it('should log info messages when threshold is Info', () => {
      logger.info('test message');

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String), // timestamp
        'Info',
        'test-category',
        'test message'
      );
    });

    it('should log warn messages when threshold is Info', () => {
      logger.warn('test message');

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Warn',
        'test-category',
        'test message'
      );
    });

    it('should log error messages when threshold is Info', () => {
      logger.error('test message');

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Error',
        'test-category',
        'test message'
      );
    });

    it('should not log debug messages when threshold is Info', () => {
      logger.debug('test message');

      expect(mockAppender.log).not.toHaveBeenCalled();
    });

    it('should not log trace messages when threshold is Info', () => {
      logger.trace('test message');

      expect(mockAppender.log).not.toHaveBeenCalled();
    });

    it('should not log silly messages when threshold is Info', () => {
      logger.silly('test message');

      expect(mockAppender.log).not.toHaveBeenCalled();
    });

    it('should log all messages when threshold is Debug', () => {
      threshold.value = LoggingLevel.Debug;

      logger.debug('debug message');
      logger.info('info message');
      logger.warn('warn message');
      logger.error('error message');

      expect(mockAppender.log).toHaveBeenCalledTimes(4);
    });

    it('should log only error messages when threshold is Error', () => {
      threshold.value = LoggingLevel.Error;

      logger.error('error message');
      logger.warn('warn message');
      logger.info('info message');

      expect(mockAppender.log).toHaveBeenCalledTimes(1);
      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Error',
        'test-category',
        'error message'
      );
    });
  });

  describe('message formatting', () => {
    beforeEach(() => {
      threshold.value = LoggingLevel.Debug; // Allow all messages for formatting tests
    });

    it('should format messages with %s placeholder', () => {
      logger.info('Hello %s', 'world');

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Info',
        'test-category',
        'Hello world'
      );
    });

    it('should format messages with %d placeholder', () => {
      logger.info('Count: %d', 42);

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Info',
        'test-category',
        'Count: 42'
      );
    });

    it('should format messages with %j placeholder', () => {
      logger.info('Object: %j', { key: 'value' });

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Info',
        'test-category',
        'Object: {"key":"value"}'
      );
    });

    it('should handle circular references in %j placeholder', () => {
      const obj: any = { key: 'value' };
      obj.self = obj;

      logger.info('Circular: %j', obj);

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Info',
        'test-category',
        'Circular: [Circular]'
      );
    });

    it('should handle multiple placeholders', () => {
      logger.info('User %s has %d items: %j', 'Alice', 5, ['a', 'b']);

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Info',
        'test-category',
        'User Alice has 5 items: ["a","b"]'
      );
    });

    it('should handle more placeholders than arguments', () => {
      logger.info('Hello %s %s', 'world');

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Info',
        'test-category',
        'Hello world %s'
      );
    });

    it('should handle fewer placeholders than arguments', () => {
      logger.info('Hello %s', 'world', 'extra');

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Info',
        'test-category',
        'Hello world'
      );
    });

    it('should handle non-number values for %d', () => {
      logger.info('Value: %d', 'not-a-number');

      expect(mockAppender.log).toHaveBeenCalledWith(
        expect.any(String),
        'Info',
        'test-category',
        'Value: NaN'
      );
    });
  });

  describe('timestamp formatting', () => {
    it('should include ISO timestamp in log messages', () => {
      const before = new Date().toISOString();
      logger.info('test');
      const after = new Date().toISOString();

      const call = (mockAppender.log as Mock).mock.calls[0];
      const timestamp = call[0];

      expect(timestamp).toBeDefined();
      expect(() => new Date(timestamp)).not.toThrow();
      expect(timestamp >= before || timestamp <= after).toBe(true);
    });
  });

  describe('multiple appenders', () => {
    it('should call all appenders', () => {
      const mockAppender2: IAppender = {
        log: vi.fn(),
      };

      const loggerWithMultiple = new Logger('test', threshold, new Set([mockAppender, mockAppender2]));

      loggerWithMultiple.info('test message');

      expect(mockAppender.log).toHaveBeenCalledTimes(1);
      expect(mockAppender2.log).toHaveBeenCalledTimes(1);
    });
  });
});