OS-agnostic handling of end-of-line characters

jest.config.cjs

@@ -6,6 +6,7 @@ const jestConfig = {
   preset: 'ts-jest/presets/default-esm',
   testEnvironment: 'node',
   testMatch: ['<rootDir>/test/**/*-test.ts'],
+  setupFiles: ['<rootDir>/test/jest.setup.cjs'],
   transform: {
     '^.+\\.tsx?$': ['ts-jest', { useESM: true }],
   },

lib/config-list.ts

@@ -1,3 +1,4 @@
+import { EOL } from 'node:os';
 import {
   BEGIN_CONFIG_LIST_MARKER,
   END_CONFIG_LIST_MARKER,
@@ -111,5 +112,5 @@ export function updateConfigsList(
     ignoreConfig
   );
 
-  return `${preList}${BEGIN_CONFIG_LIST_MARKER}\n\n${list}\n\n${END_CONFIG_LIST_MARKER}${postList}`;
+  return `${preList}${BEGIN_CONFIG_LIST_MARKER}${EOL}${EOL}${list}${EOL}${EOL}${END_CONFIG_LIST_MARKER}${postList}`;
 }

lib/generator.ts

@@ -1,3 +1,4 @@
+import { EOL } from 'node:os';
 import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs';
 import { dirname, join, relative, resolve } from 'node:path';
 import { getAllNamedOptions, hasOptions } from './rule-options.js';
@@ -168,16 +169,18 @@ export async function generate(path: string, options?: GenerateOptions) {
       // The rule doc header will be added later.
       let newRuleDocContents = [
         ruleDocSectionInclude.length > 0
-          ? ruleDocSectionInclude.map((title) => `## ${title}`).join('\n\n')
+          ? ruleDocSectionInclude
+              .map((title) => `## ${title}`)
+              .join(`${EOL}${EOL}`)
           : undefined,
         ruleHasOptions
-          ? `## Options\n\n${BEGIN_RULE_OPTIONS_LIST_MARKER}\n${END_RULE_OPTIONS_LIST_MARKER}`
+          ? `## Options${EOL}${EOL}${BEGIN_RULE_OPTIONS_LIST_MARKER}${EOL}${END_RULE_OPTIONS_LIST_MARKER}`
           : undefined,
       ]
         .filter((section) => section !== undefined)
-        .join('\n\n');
+        .join(`${EOL}${EOL}`);
       if (newRuleDocContents !== '') {
-        newRuleDocContents = `\n${newRuleDocContents}\n`;
+        newRuleDocContents = `${EOL}${newRuleDocContents}${EOL}`;
       }
 
       mkdirSync(dirname(pathToDoc), { recursive: true });

lib/markdown.ts

@@ -1,3 +1,5 @@
+import { EOL } from 'node:os';
+
 // General helpers for dealing with markdown files / content.
 
 /**
@@ -12,7 +14,7 @@ export function replaceOrCreateHeader(
   newHeader: string,
   marker: string
 ) {
-  const lines = markdown.split('\n');
+  const lines = markdown.split(EOL);
 
   const titleLineIndex = lines.findIndex((line) => line.startsWith('# '));
   const markerLineIndex = lines.indexOf(marker);
@@ -22,16 +24,18 @@ export function replaceOrCreateHeader(
   // Any YAML front matter or anything else above the title should be kept as-is ahead of the new header.
   const preHeader = lines
     .slice(0, Math.max(titleLineIndex, dashesLineIndex2 + 1))
-    .join('\n');
+    .join(EOL);
 
   // Anything after the marker comment, title, or YAML front matter should be kept as-is after the new header.
   const postHeader = lines
     .slice(
       Math.max(markerLineIndex + 1, titleLineIndex + 1, dashesLineIndex2 + 1)
     )
-    .join('\n');
+    .join(EOL);
 
-  return `${preHeader ? `${preHeader}\n` : ''}${newHeader}\n${postHeader}`;
+  return `${
+    preHeader ? `${preHeader}${EOL}` : ''
+  }${newHeader}${EOL}${postHeader}`;
 }
 
 /**
@@ -42,7 +46,7 @@ export function findSectionHeader(
   str: string
 ): string | undefined {
   // Get all the matching strings.
-  const regexp = new RegExp(`## .*${str}.*\n`, 'giu');
+  const regexp = new RegExp(`## .*${str}.*${EOL}`, 'giu');
   const sectionPotentialMatches = [...markdown.matchAll(regexp)].map(
     (match) => match[0]
   );
@@ -64,7 +68,7 @@ export function findSectionHeader(
 }
 
 export function findFinalHeaderLevel(str: string) {
-  const lines = str.split('\n');
+  const lines = str.split(EOL);
   const finalHeader = lines.reverse().find((line) => line.match('^(#+) .+$'));
   return finalHeader ? finalHeader.indexOf(' ') : undefined;
 }

lib/rule-doc-notices.ts

@@ -1,3 +1,4 @@
+import { EOL } from 'node:os';
 import { END_RULE_HEADER_MARKER } from './comment-markers.js';
 import {
   EMOJI_DEPRECATED,
@@ -523,5 +524,5 @@ export function generateRuleHeaderLines(
     ),
     '',
     END_RULE_HEADER_MARKER,
-  ].join('\n');
+  ].join(EOL);
 }

lib/rule-list-legend.ts

@@ -1,3 +1,4 @@
+import { EOL } from 'node:os';
 import {
   EMOJI_DEPRECATED,
   EMOJI_FIXABLE,
@@ -287,5 +288,5 @@ export function generateLegend(
     );
   }
 
-  return legends.join('\\\n'); // Back slash ensures these end up displayed on separate lines.
+  return legends.join(`\\${EOL}`); // Back slash ensures these end up displayed on separate lines.
 }

lib/rule-list.ts

@@ -1,3 +1,4 @@
+import { EOL } from 'node:os';
 import {
   BEGIN_RULE_LIST_MARKER,
   END_RULE_LIST_MARKER,
@@ -288,7 +289,7 @@ function generateRuleListMarkdownForRulesAndHeaders(
     );
   }
 
-  return parts.join('\n\n');
+  return parts.join(`${EOL}${EOL}`);
 }
 
 /**
@@ -546,7 +547,7 @@ export function updateRulesList(
     urlRuleDoc
   );
 
-  const newContent = `${legend ? `${legend}\n\n` : ''}${list}`;
+  const newContent = `${legend ? `${legend}${EOL}${EOL}` : ''}${list}`;
 
-  return `${preList}${BEGIN_RULE_LIST_MARKER}\n\n${newContent}\n\n${END_RULE_LIST_MARKER}${postList}`;
+  return `${preList}${BEGIN_RULE_LIST_MARKER}${EOL}${EOL}${newContent}${EOL}${EOL}${END_RULE_LIST_MARKER}${postList}`;
 }

lib/rule-options-list.ts

@@ -1,3 +1,4 @@
+import { EOL } from 'node:os';
 import {
   BEGIN_RULE_OPTIONS_LIST_MARKER,
   END_RULE_OPTIONS_LIST_MARKER,
@@ -159,5 +160,5 @@ export function updateRuleOptionsList(
   // New rule options list.
   const list = generateRuleOptionsListMarkdown(rule);
 
-  return `${preList}${BEGIN_RULE_OPTIONS_LIST_MARKER}\n\n${list}\n\n${END_RULE_OPTIONS_LIST_MARKER}${postList}`;
+  return `${preList}${BEGIN_RULE_OPTIONS_LIST_MARKER}${EOL}${EOL}${list}${EOL}${EOL}${END_RULE_OPTIONS_LIST_MARKER}${postList}`;
 }

lib/string.ts

@@ -1,3 +1,5 @@
+import { EOL } from 'node:os';
+
 export function toSentenceCase(str: string) {
   return str.replace(/^\w/u, function (txt) {
     return txt.charAt(0).toUpperCase() + txt.slice(1).toLowerCase();
@@ -20,7 +22,7 @@ export function capitalizeOnlyFirstLetter(str: string) {
 }
 
 function sanitizeMarkdownTableCell(text: string): string {
-  return text.replace(/\|/gu, '\\|').replace(/\n/gu, '<br/>');
+  return text.replace(/\|/gu, '\\|').replace(new RegExp(EOL, 'gu'), '<br/>');
 }
 
 export function sanitizeMarkdownTable(

test/jest.setup.cjs

@@ -0,0 +1,6 @@
+const os = require('node:os');
+const sinon = require('sinon');
+
+module.exports = function () {
+  sinon.stub(os, 'EOL').value('\n'); // Stub os.EOL to always be '\n' for testing/snapshot purposes.
+};