Remove an unused disable directive together with its line

eslint core replaces an unused directive comment with a single space,
so --fix left a blank line wherever the comment sat on a line of its
own. A processor now widens that fix: the whole line when the comment
is alone on it, otherwise the comment and the space beside it. Fixes
with a rule id, and the removal of one rule name out of several, are
unchanged.

packages/dev/src/directives.spec.ts

@@ -0,0 +1,95 @@
+// Copyright 2017-2026 @pezkuwi/dev authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+/// <reference types="@pezkuwi/dev-test/globals.d.ts" />
+
+import type { Linter } from 'eslint';
+
+import { ESLint } from 'eslint';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+
+// Loaded by path: the config directory is plain JavaScript outside this
+// package's TypeScript root.
+const PROCESSOR = path.join(process.cwd(), 'packages/dev/config/eslint.directives.js');
+
+const SOURCE = `const a = 1;
+// eslint-disable-next-line no-console
+const b = 2;
+
+function f () {
+  // eslint-disable-next-line no-console
+  return a + b;
+}
+
+f(); // eslint-disable-line no-console
+/* eslint-disable-next-line no-console */ export const c = 3;
+// eslint-disable-next-line no-alert, no-console
+console.log(c);
+`;
+
+const FIXED = `const a = 1;
+const b = 2;
+
+function f () {
+  return a + b;
+}
+
+f();
+export const c = 3;
+// eslint-disable-next-line no-console
+console.log(c);
+`;
+
+async function fix (processor?: Linter.Processor): Promise<string> {
+  const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'directives-'));
+
+  try {
+    fs.writeFileSync(path.join(dir, 'sample.js'), SOURCE);
+
+    const eslint = new ESLint({
+      cwd: dir,
+      fix: true,
+      overrideConfig: [{
+        files: ['**/*.js'],
+        linterOptions: { reportUnusedDisableDirectives: 'error' },
+        ...(processor ? { processor } : {}),
+        rules: { 'no-alert': 'error', 'no-console': 'error' }
+      }],
+      overrideConfigFile: true
+    });
+    const [result] = await eslint.lintFiles(['sample.js']);
+
+    return result.output ?? SOURCE;
+  } finally {
+    fs.rmSync(dir, { force: true, recursive: true });
+  }
+}
+
+describe('directiveLines', (): void => {
+  it('removes an unused directive with its line or the space around it', async (): Promise<void> => {
+    const { directiveLines } = await import(PROCESSOR) as { directiveLines: Linter.Processor };
+
+    expect(await fix(directiveLines)).toEqual(FIXED);
+  });
+
+  it('is needed: core leaves a space where each comment was', async (): Promise<void> => {
+    expect((await fix()).split('\n')).toEqual([
+      'const a = 1;',
+      ' ',
+      'const b = 2;',
+      '',
+      'function f () {',
+      '   ',
+      '  return a + b;',
+      '}',
+      '',
+      'f();  ',
+      '  export const c = 3;',
+      '// eslint-disable-next-line no-console',
+      'console.log(c);',
+      ''
+    ]);
+  });
+});