refactor: move record source validation to its own file

src/bunyan/from-json-string.test.ts

@@ -1,7 +1,7 @@
 import test from 'ava';
 import {deleteProperty} from 'dot-prop';
 import fromJsonString from './from-json-string.js';
-import type BunyanRecord from './record.js';
+import {type BunyanRecord} from './record.js';
 
 const bunyanRecord: BunyanRecord = {
   v: 0,

src/bunyan/from-json-string.ts

@@ -1,5 +1,5 @@
 import isBunyanRecord from './is-record.js';
-import type BunyanRecord from './record.js';
+import {type BunyanRecord} from './record.js';
 
 function fromJsonString(json: string): BunyanRecord {
   const record: unknown = JSON.parse(json, (key, value) => {

src/bunyan/index.ts

@@ -1,5 +1,6 @@
+export {default as isSource} from './is-source.js';
 export {default as isBunyanRecord} from './is-record.js';
-export {type default as BunyanRecord} from './record.js';
+export type {BunyanRecord, Source} from './record.js';
 export {default as coreFields} from './core-fields.js';
 export {default as fromJsonString} from './from-json-string.js';
 export {default as levels} from './levels.js';

src/bunyan/is-record.test.ts

@@ -1,6 +1,6 @@
 import test from 'ava';
 import {deleteProperty} from 'dot-prop';
-import type BunyanRecord from './record.js';
+import {type BunyanRecord} from './record.js';
 import isBunyanRecord from './is-record.js';
 
 const bunyanRecord: Readonly<BunyanRecord> = {

src/bunyan/is-record.ts

@@ -1,5 +1,6 @@
 import is from '@sindresorhus/is';
-import type BunyanRecord from './record.js';
+import type {BunyanRecord} from './record.js';
+import isSource from './is-source.js';
 
 function isBunyanRecord(value: unknown): value is BunyanRecord {
   return (
@@ -11,10 +12,7 @@ function isBunyanRecord(value: unknown): value is BunyanRecord {
     is.number(value.pid) &&
     is.date(value.time) &&
     is.string(value.msg) &&
-    (is.undefined(value.src) ||
-      (is.plainObject(value.src) &&
-        is.number(value.src.line) &&
-        (is.undefined(value.src.func) || is.string(value.src.func))))
+    (is.undefined(value.src) || isSource(value.src))
   );
 }
 

src/bunyan/is-source.test.ts

@@ -0,0 +1,40 @@
+import test from 'ava';
+import {deleteProperty} from 'dot-prop';
+import {type BunyanRecord, type Source} from './record.js';
+import isSource from './is-source.js';
+
+const source: Readonly<BunyanRecord['src']> = {
+  file: '',
+  line: 0,
+  func: '',
+};
+
+const returnsWithout = test.macro<[boolean, keyof Source]>({
+  exec(t, expected, key) {
+    const value = structuredClone(source);
+    deleteProperty(value, key);
+    (expected ? t.true : t.false)(isSource(value));
+  },
+  title(_, expected, key) {
+    const expectedString = expected ? 'true' : 'false';
+    return `returns "${expectedString}" for a source without "${key}"`;
+  },
+});
+
+test(returnsWithout, false, 'line');
+test(returnsWithout, true, 'func');
+
+test('returns "true" for a source with all values', (t) => {
+  t.true(isSource(source));
+});
+
+test('returns "false" for an empty object', (t) => {
+  t.false(isSource({}));
+});
+
+test('narrows the type to "Source"', (t) => {
+  const value: unknown = structuredClone(source);
+  if (isSource(value)) {
+    t.is(value.file, source.file);
+  }
+});

src/bunyan/is-source.ts

@@ -0,0 +1,12 @@
+import is from '@sindresorhus/is';
+import type {Source} from './record.js';
+
+function isSource(value: unknown): value is Source {
+  return (
+    is.plainObject(value) &&
+    is.number(value.line) &&
+    (is.undefined(value.func) || is.string(value.func))
+  );
+}
+
+export default isSource;

src/bunyan/record.ts

@@ -1,3 +1,9 @@
+type Source = {
+  file: string;
+  line: number;
+  func?: string;
+};
+
 type BunyanRecord = {
   [key: string]: unknown;
   v: number;
@@ -7,11 +13,7 @@ type BunyanRecord = {
   pid: number;
   time: Date;
   msg: string;
-  src?: {
-    file: string;
-    line: number;
-    func?: string;
-  };
+  src?: Source;
 };
 
-export default BunyanRecord;
+export type {Source, BunyanRecord};

src/formatter/formatter.ts

@@ -3,7 +3,7 @@ import bunyan from 'bunyan';
 import type {ChalkInstance as Chalk} from 'chalk';
 import chalk from 'chalk';
 import stringify from 'json-stringify-pretty-compact';
-import type BunyanRecord from '../bunyan/record.js';
+import {type BunyanRecord} from '../bunyan/record.js';
 import type {PublicOptions, Options} from '../options.js';
 import {schema} from '../options.js';
 import type {ParsedRecord} from '../parser/parser.js';

src/parser/parser.test.ts

@@ -1,6 +1,5 @@
 import test from 'ava';
-import type BunyanRecord from '../bunyan/record.js';
-import type {ParsedRecord} from './parser.js';
+import {type BunyanRecord} from '../bunyan/record.js';
 import Parser from './parser.js';
 
 const options = {