fix(utils): handle raw hashes and queries in url relative() + add tests

src/utils/__tests__/url.test.mjs

@@ -0,0 +1,44 @@
+import { strict as assert } from 'node:assert';
+import { describe, it } from 'node:test';
+
+import { relative } from '../url.mjs';
+
+describe('url util', () => {
+  describe('relative()', () => {
+    it('returns the same URL if it includes a protocol', () => {
+      assert.equal(
+        relative('https://example.com', '/foo/bar'),
+        'https://example.com'
+      );
+      assert.equal(
+        relative('http://nodejs.org', '/foo/bar'),
+        'http://nodejs.org'
+      );
+    });
+
+    it('returns the same URL if it starts with a hash fragment', () => {
+      assert.equal(relative('#fragment', '/foo/index.html'), '#fragment');
+    });
+
+    it('returns the same URL if it starts with a query string', () => {
+      assert.equal(relative('?query=true', '/foo/index.html'), '?query=true');
+    });
+
+    it('returns the relative path between two URLs', () => {
+      assert.equal(relative('/api/fs.html', '/api/crypto.html'), 'fs.html');
+      assert.equal(
+        relative('/api/fs.html#slug', '/api/fs.html'),
+        'fs.html#slug'
+      );
+      assert.equal(
+        relative('/foo/bar.html', '/baz/qux.html'),
+        '../foo/bar.html'
+      );
+      assert.equal(
+        relative('/foo/bar.html', '/foo/bar/baz.html'),
+        '../bar.html'
+      );
+      assert.equal(relative('/a/b/c.html', '/x/y/z.html'), '../../a/b/c.html');
+    });
+  });
+});

src/utils/url.mjs

@@ -9,6 +9,10 @@ export const relative = (to, from) => {
     return to;
   }
 
+  if (to.startsWith('#') || to.startsWith('?')) {
+    return to;
+  }
+
   const a = to.split('/').filter(Boolean);
   const b = from.split('/').slice(0, -1).filter(Boolean);