feat: markdownlint rule to disallow newline in link text (#69)

configs/markdownlint.json

@@ -26,6 +26,7 @@
   "no-inline-html": false,
   "no-angle-brackets": false,
   "no-curly-braces": false,
+  "no-newline-in-links": false,
   "link-image-style": {
     "shortcut": false
   }

markdownlint-rules/emd004.js

@@ -0,0 +1,30 @@
+const { addError, filterTokens } = require('markdownlint/helpers');
+
+module.exports = {
+  names: ['EMD004', 'no-newline-in-links'],
+  description: 'Newlines inside link text',
+  tags: ['newline', 'links'],
+  parser: 'markdownit',
+  function: function EMD004(params, onError) {
+    filterTokens(params, 'inline', (token) => {
+      const { children } = token;
+      let { lineNumber } = token;
+      let inLink = false;
+      for (const child of children) {
+        const { type } = child;
+        if (type === 'link_open') {
+          inLink = true;
+        } else if (type === 'link_close') {
+          inLink = false;
+        } else if (type === 'softbreak') {
+          if (inLink) {
+            addError(onError, lineNumber);
+            break;
+          } else {
+            lineNumber++;
+          }
+        }
+      }
+    });
+  },
+};

markdownlint-rules/index.js

@@ -1,4 +1,5 @@
 const EMD002 = require('./emd002.js');
 const EMD003 = require('./emd003.js');
+const EMD004 = require('./emd004.js');
 
-module.exports = [EMD002, EMD003];
+module.exports = [EMD002, EMD003, EMD004];

tests/__snapshots__/electron-markdownlint.spec.ts.snap

@@ -1,5 +1,13 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
+exports[`electron-markdownlint > should not allow newlines in link text if EMD004 enabled 1`] = `
+"<root>newline-in-link-text.md:1 EMD004/no-newline-in-links Newlines inside link text
+<root>newline-in-link-text.md:4 EMD004/no-newline-in-links Newlines inside link text
+<root>newline-in-link-text.md:7 EMD004/no-newline-in-links Newlines inside link text
+<root>newline-in-link-text.md:10 EMD004/no-newline-in-links Newlines inside link text
+"
+`;
+
 exports[`electron-markdownlint > should not allow opening angle brackets if EMD002 enabled 1`] = `
 "<root>angle-brackets.md:3:13 EMD002/no-angle-brackets No unescaped opening angle brackets in text (does not play nice with MDX) [Unescaped opening angle bracket]
 <root>angle-brackets.md:9:16 EMD002/no-angle-brackets No unescaped opening angle brackets in text (does not play nice with MDX) [Unescaped opening angle bracket]

tests/electron-markdownlint.spec.ts

@@ -117,4 +117,46 @@ describe('electron-markdownlint', () => {
     expect(stdout).toBe('');
     expect(status).toEqual(0);
   });
+
+  it('should not allow newlines in link text if EMD004 enabled', () => {
+    const { status, stderr, stdout } = cp.spawnSync(
+      process.execPath,
+      [
+        path.resolve(__dirname, '../dist/bin/markdownlint-cli-wrapper.js'),
+        '--enable',
+        'EMD004',
+        '--',
+        path.resolve(FIXTURES_DIR, 'newline-in-link-text.md'),
+      ],
+      { stdio: 'pipe', encoding: 'utf-8' },
+    );
+
+    let fixturesRoot = `${FIXTURES_DIR}${path.sep}`;
+
+    if (os.platform() === 'win32') {
+      fixturesRoot = fixturesRoot.replace(/\\/g, '\\\\');
+    }
+
+    expect(stderr.replace(new RegExp(fixturesRoot, 'g'), '<root>')).toMatchSnapshot();
+    expect(stdout).toBe('');
+    expect(status).toEqual(1);
+  });
+
+  it('should allow newlines in link text if EMD004 not enabled', () => {
+    const { status, stderr, stdout } = cp.spawnSync(
+      process.execPath,
+      [
+        path.resolve(__dirname, '../dist/bin/markdownlint-cli-wrapper.js'),
+        '--disable',
+        'EMD004',
+        '--',
+        path.resolve(FIXTURES_DIR, 'newline-in-link-text.md'),
+      ],
+      { stdio: 'pipe', encoding: 'utf-8' },
+    );
+
+    expect(stderr).toBe('');
+    expect(stdout).toBe('');
+    expect(status).toEqual(0);
+  });
 });

tests/fixtures/angle-brackets.md

@@ -88,9 +88,9 @@ protocol.registerSchemesAsPrivileged([
 ])
 ```
 
-A standard scheme adheres to what RFC 3986 calls [generic URI
-syntax](https://tools.ietf.org/html/rfc3986#section-3). For example `http` and
-`https` are standard schemes, while `file` is not.
+A standard scheme adheres to what RFC 3986 calls
+[generic URI syntax](https://tools.ietf.org/html/rfc3986#section-3).
+For example `http` and `https` are standard schemes, while `file` is not.
 
 Registering a scheme as standard allows relative and absolute resources to
 be resolved correctly when served. Otherwise the scheme will behave like the

tests/fixtures/newline-in-link-text.md

@@ -0,0 +1,11 @@
+This has [a link
+with a newline](https://google.com)
+
+This has [a link
+    with a newline](https://google.com)
+
+This has [
+a link with a newline](https://google.com)
+
+This has [a link with a newline
+](https://google.com)