feat: separate built-in formatters into separate files

src/formatters/full.spec.ts

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+import 'expect-more-jest';
+import stringify from 'fast-safe-stringify';
+import LogMessage from '../LogMessage';
+import fullFormatter from './full';
+
+const defaultOpts = {
+  meta: {},
+  dynamicMeta: null,
+  tags: [],
+  levelKey: '_logLevel',
+  messageKey: 'msg',
+  tagsKey: '_tags',
+  replacer: null
+};
+
+describe('formatters/full', () => {
+  it('should export a closure function', () => {
+    expect(typeof fullFormatter).toBe('function');
+  });
+
+  it('should return a formatter function', () => {
+    expect(typeof fullFormatter()).toBe('function');
+  });
+
+  it('should overrride configuration', () => {
+    const formatter = fullFormatter({
+      includeTimestamp: false,
+      includeTags: false,
+      includeMeta: false,
+      separator: '\t',
+      inspectOptions: {
+        colors: false,
+        maxArrayLength: 25
+      }
+    });
+
+    const cfg = formatter._cfg!;
+
+    expect(cfg.includeTimestamp).toBe(false);
+    expect(cfg.includeTags).toBe(false);
+    expect(cfg.includeMeta).toBe(false);
+    expect(cfg.separator).toBe('\t');
+    expect(cfg.inspectOptions).toEqual({
+      depth: Infinity,
+      colors: false,
+      maxArrayLength: 25
+    });
+  });
+
+  it('should skip the timestamp if includeTimestamp is false', () => {
+    const msg = new LogMessage({
+      level: 'info',
+      msg: 'info test',
+      meta: {},
+      tags: []
+    }, defaultOpts);
+
+    const formatter = fullFormatter({
+      includeTimestamp: false
+    });
+
+    expect(formatter(msg, defaultOpts, stringify)).toMatch(/^INFO\tinfo test$/);
+  });
+});

src/formatters/full.ts

@@ -0,0 +1,62 @@
+import { FormatPlugin } from '../typings.js';
+import { inspect, InspectOptions } from 'util';
+
+type FullFormatterCfg = {
+  includeTimestamp?: boolean;
+  formatTimestamp?: (timestamp: Date) => string;
+  includeTags?: boolean;
+  includeMeta?: boolean;
+  separator?: string;
+  inspectOptions?: InspectOptions;
+};
+
+/**
+ * Full formatter for log messages.
+ * @param {object} cfg  Configuration object for the formatter.
+ * @returns {FormatPlugin} The full formatter function.
+ */
+export default function fullFormatter(cfg: FullFormatterCfg = {}): FormatPlugin {
+  const fmCfg = {
+    includeTimestamp: true,
+    formatTimestamp: (timestamp: Date) => timestamp.toISOString(),
+    includeTags: true,
+    includeMeta: true,
+    separator: '\t',
+    ...cfg
+  };
+
+  fmCfg.inspectOptions = {
+    depth: Infinity,
+    colors: true,
+    ...(fmCfg.inspectOptions ?? {})
+  };
+
+  const fullFmt: FormatPlugin = (ctx): string => {
+    const msg = [];
+    if(fmCfg.includeTimestamp) {
+      msg.push(fmCfg.formatTimestamp(new Date()));
+    }
+
+    msg.push(ctx.level.toUpperCase(), ctx.msg);
+
+    const parts = [
+      msg.join(fmCfg.separator)
+    ];
+
+    if(fmCfg.includeTags && ctx.tags.length) {
+      const tags = ctx.tags.map(tag => `${tag}`).join(', ');
+      parts.push(`→ ${tags}`);
+    }
+
+    if(fmCfg.includeMeta && Object.keys(ctx.meta).length) {
+      const meta = inspect(ctx.meta, fmCfg.inspectOptions!);
+      parts.push(`→ ${meta.replace(/\n/g, '\n  ')}`);
+    }
+
+    return parts.join('\n');
+  };
+
+  fullFmt._cfg = fmCfg;
+
+  return fullFmt;
+}

src/formatters/index.ts

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+export { default as json } from './json.js';
+export { default as full } from './full.js';
+export { default as minimal } from './minimal.js';

src/formatters/json.spec.ts

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+import 'expect-more-jest';
+import stringify from 'fast-safe-stringify';
+import LogMessage from '../LogMessage';
+import jsonFormatter from './json';
+
+const defaultOpts = {
+  meta: {},
+  dynamicMeta: null,
+  tags: [],
+  levelKey: '_logLevel',
+  messageKey: 'msg',
+  tagsKey: '_tags',
+  replacer: null
+};
+
+const logObject = {
+  level: 'info',
+  msg: 'info test',
+  meta: {},
+  tags: []
+};
+
+
+describe('formatters/json', () => {
+  it('should export a closure function', () => {
+    expect(typeof jsonFormatter).toBe('function');
+  });
+
+  it('should return a formatter function', () => {
+    expect(typeof jsonFormatter()).toBe('function');
+  });
+
+  const replacerOpts = {
+    ...defaultOpts,
+    meta: { ssn: '444-55-6666' },
+    replacer(key: string, value: unknown) {
+      if(key === 'ssn') {
+        return `${(value as string).substring(0, 3)}-**-****`;
+      }
+
+      return value;
+    }
+  };
+
+  const msg = new LogMessage({ ...logObject }, replacerOpts);
+
+  const formatter = jsonFormatter();
+  const result = formatter(msg, replacerOpts, stringify);
+
+  it('should return log in JSON format', () => {
+    expect(result).toBeJsonString();
+  });
+
+  it('should run replacer function', () => {
+    expect(JSON.parse(result).ssn).toBe('444-**-****');
+  });
+
+  it('should not run replacer function when not defined', () => {
+    const msgNoReplacer = new LogMessage({ ...logObject }, {
+      ...defaultOpts,
+      meta: { ssn: '444-55-6666' }
+    });
+
+    const noReplacerResult = formatter(msgNoReplacer, defaultOpts, stringify);
+
+    expect(JSON.parse(noReplacerResult).ssn).toBe('444-55-6666');
+  });
+
+  it('should pretty print JSON when dev is "true"', () => {
+    const opts = {
+      ...defaultOpts,
+      dev: true,
+      meta: { ssn: '444-55-6666' }
+    };
+
+    const msgDev = new LogMessage({ ...logObject }, opts);
+    const prettyResult = formatter(msgDev, opts, stringify);
+
+    expect(/\n/g.test(prettyResult)).toBe(true);
+  });
+});

src/formatters/json.ts

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+import { FormatPlugin } from '../typings.js';
+
+/**
+ * JSON formatter for log messages.
+ * @returns {FormatPlugin} The JSON formatter function.
+ */
+export default function jsonFormatter(): FormatPlugin {
+  const jsonFmt: FormatPlugin = (ctx, options, stringify): string =>
+    stringify(ctx.value, options.replacer ?? undefined, options.dev ? 2 : 0);
+
+  return jsonFmt;
+}

src/formatters/minimal.spec.ts

@@ -0,0 +1,73 @@
+import 'expect-more-jest';
+import stringify from 'fast-safe-stringify';
+import LogMessage from '../LogMessage';
+import minimalFormatter from './minimal';
+
+const defaultOpts = {
+  meta: {},
+  dynamicMeta: null,
+  tags: [],
+  levelKey: '_logLevel',
+  messageKey: 'msg',
+  tagsKey: '_tags',
+  replacer: null
+};
+
+describe('formatters/minmal', () => {
+  it('should export a closure function', () => {
+    expect(typeof minimalFormatter).toBe('function');
+  });
+
+  it('should return a formatter function', () => {
+    expect(typeof minimalFormatter()).toBe('function');
+  });
+
+  it('should overrride configuration', () => {
+    const formatter = minimalFormatter({
+      includeTimestamp: false,
+      separator: '\t'
+    });
+
+    const cfg = formatter._cfg!;
+
+    expect(cfg.includeTimestamp).toBe(false);
+    expect(cfg.separator).toBe('\t');
+  });
+
+  it('should format timestamp as ISO string by default', () => {
+    const formatter = minimalFormatter();
+
+    // @ts-expect-error - we're testing the internals here
+    expect((formatter._cfg!).formatTimestamp(new Date())).toMatch(/^\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z)$/);
+  });
+
+  it('should include the timestamp if includeTimestamp is true', () => {
+    const msg = new LogMessage({
+      level: 'info',
+      msg: 'info test',
+      meta: {},
+      tags: []
+    }, defaultOpts);
+
+    const formatter = minimalFormatter({
+      includeTimestamp: true
+    });
+
+    expect(formatter(msg, defaultOpts, stringify)).toMatch(/^\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z) | INFO | info test$/);
+  });
+
+  it('should skip the timestamp if includeTimestamp is false', () => {
+    const msg = new LogMessage({
+      level: 'info',
+      msg: 'info test',
+      meta: {},
+      tags: []
+    }, defaultOpts);
+
+    const formatter = minimalFormatter({
+      includeTimestamp: false
+    });
+
+    expect(formatter(msg, defaultOpts, stringify)).toMatch(/^INFO | info test$/);
+  });
+});

src/formatters/minimal.ts

@@ -0,0 +1,36 @@
+import { FormatPlugin } from '../typings.js';
+
+type MinimalFormatterCfg = {
+  includeTimestamp?: boolean;
+  formatTimestamp?: (timestamp: Date) => string;
+  separator?: string;
+};
+
+/**
+ * Minimal formatter for log messages.
+ * @param {object} cfg  Configuration object for the formatter.
+ * @returns {FormatPlugin} The minimal formatter function.
+ */
+export default function minimalFormatter(cfg: MinimalFormatterCfg = {}): FormatPlugin {
+  const fmCfg = {
+    includeTimestamp: false,
+    formatTimestamp: (timestamp: Date) => timestamp.toISOString(),
+    separator: ' | ',
+    ...cfg
+  };
+
+  const minimalFmt: FormatPlugin = (ctx): string => {
+    const parts = [];
+    if(fmCfg.includeTimestamp) {
+      parts.push(fmCfg.formatTimestamp(new Date()));
+    }
+
+    parts.push(ctx.level.toUpperCase(), ctx.msg);
+
+    return parts.join(fmCfg.separator);
+  };
+
+  minimalFmt._cfg = fmCfg;
+
+  return minimalFmt;
+}