fix(subdirectory): unblock CI on subdirectory-helpers PR

Three concrete failures from the first CI run on 0e98228aa8, addressed:

1. Jest hoisting (sharded-jest-tests shard 3): the Layer 5 mock factory
   referenced `APPLICATION_ROOT_MOCK` from outer scope. Jest hoists
   `jest.mock()` above all top-level statements, so the variable was
   undefined when the factory ran, producing
   "module factory of jest.mock() is not allowed to reference any
   out-of-scope variables". Renamed to `mockApplicationRoot` — Jest
   carves out an exception for variables prefixed with `mock`. Comment
   added so the next contributor doesn't lose ten minutes to the
   rename rule.

2. oxlint (pre-commit): two errors in normalizeBackendUrls.ts.
   - "walk was used before it was defined": moved the `walk` helper
     above its caller `normalizeBackendUrls`. The hoisting was valid JS
     but oxlint enforces textual order.
   - "Do not use `new Array(singleArgument)`": replaced
     `new Array(value.length)` with a `[]` + push pattern. Same
     allocation cost, no surprise sparse-array semantics.

3. prettier (pre-commit): line-wrap the React type imports in
   navigationUtils.ts and tighten the conditional layout in
   normalizeBackendUrls.ts to match prettier's expected output.

Outstanding: the `playwright-tests (chromium, /app/prefix)` failures
look like infrastructure flakiness — the failing tests (bulk export
dashboards, create dataset wizard, duplicate dataset) all hit
`page.goto: Test timeout of 30000ms exceeded` and
`apiRequestContext.post: socket hang up`, and don't exercise the one
production code path this PR touches (SliceHeaderControls Cmd-click).
Watching the next run before treating it as a real failure.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

superset-frontend/packages/superset-ui-core/src/connection/normalizeBackendUrls.ts

@@ -159,27 +159,15 @@ export function normalizeBackendUrlString(
   return value;
 }
 
-/**
- * Recursively normalise URL fields in a JSON-shaped value.
- *
- * Returns a new value when normalisation changed anything; otherwise returns
- * the input by reference so consumers can compare with `===`.
- */
-export function normalizeBackendUrls<T>(value: T, options: NormalizeOptions): T {
-  const root = stripTrailingSlash(options.applicationRoot);
-  if (!root) return value;
-  return walk(value, root) as T;
-}
-
 function walk(value: unknown, root: string): unknown {
   if (Array.isArray(value)) {
     let changed = false;
-    const out: unknown[] = new Array(value.length);
+    const out: unknown[] = [];
     for (let index = 0; index < value.length; index += 1) {
       const item = value[index];
       const next = walk(item, root);
       if (next !== item) changed = true;
-      out[index] = next;
+      out.push(next);
     }
     return changed ? out : value;
   }
@@ -190,10 +178,7 @@ function walk(value: unknown, root: string): unknown {
     for (const key of Object.keys(value)) {
       const fieldValue = value[key];
       let nextValue: unknown;
-      if (
-        NORMALIZED_URL_FIELDS.has(key) &&
-        typeof fieldValue === 'string'
-      ) {
+      if (NORMALIZED_URL_FIELDS.has(key) && typeof fieldValue === 'string') {
         nextValue = normalizeBackendUrlString(fieldValue, {
           applicationRoot: root,
         });
@@ -208,3 +193,18 @@ function walk(value: unknown, root: string): unknown {
 
   return value;
 }
+
+/**
+ * Recursively normalise URL fields in a JSON-shaped value.
+ *
+ * Returns a new value when normalisation changed anything; otherwise returns
+ * the input by reference so consumers can compare with `===`.
+ */
+export function normalizeBackendUrls<T>(
+  value: T,
+  options: NormalizeOptions,
+): T {
+  const root = stripTrailingSlash(options.applicationRoot);
+  if (!root) return value;
+  return walk(value, root) as T;
+}

superset-frontend/src/dashboard/components/SliceHeaderControls/SliceHeaderControls.subdirectory.test.tsx

@@ -44,10 +44,13 @@ import SliceHeaderControls, { SliceHeaderControlsProps } from '.';
 // goes green.
 // =============================================================================
 
-const APPLICATION_ROOT_MOCK = jest.fn<string, []>(() => '');
+// Variable name must start with `mock` so Jest's hoisted `jest.mock()`
+// factory can reference it. Renaming this prefix breaks the suite with
+// "module factory is not allowed to reference any out-of-scope variables".
+const mockApplicationRoot = jest.fn<string, []>(() => '');
 
 jest.mock('src/utils/getBootstrapData', () => ({
-  applicationRoot: () => APPLICATION_ROOT_MOCK(),
+  applicationRoot: () => mockApplicationRoot(),
 }));
 
 const SLICE_ID = 371;
@@ -124,7 +127,7 @@ describe('SliceHeaderControls — Cmd-click "Edit chart" under subdirectory depl
   let openSpy: jest.SpyInstance;
 
   beforeEach(() => {
-    APPLICATION_ROOT_MOCK.mockReturnValue('');
+    mockApplicationRoot.mockReturnValue('');
     openSpy = jest.spyOn(window, 'open').mockImplementation(() => null);
   });
 
@@ -133,7 +136,7 @@ describe('SliceHeaderControls — Cmd-click "Edit chart" under subdirectory depl
   });
 
   test('opens the unprefixed exploreUrl when application root is empty', async () => {
-    APPLICATION_ROOT_MOCK.mockReturnValue('');
+    mockApplicationRoot.mockReturnValue('');
     renderControls();
 
     userEvent.click(screen.getByRole('button', { name: 'More Options' }));
@@ -148,7 +151,7 @@ describe('SliceHeaderControls — Cmd-click "Edit chart" under subdirectory depl
   });
 
   test('opens the prefixed exploreUrl when deployed under a subdirectory', async () => {
-    APPLICATION_ROOT_MOCK.mockReturnValue('/superset');
+    mockApplicationRoot.mockReturnValue('/superset');
     renderControls();
 
     userEvent.click(screen.getByRole('button', { name: 'More Options' }));

superset-frontend/src/utils/navigationUtils.ts

@@ -16,7 +16,11 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import { createElement, type AnchorHTMLAttributes, type ReactElement } from 'react';
+import {
+  createElement,
+  type AnchorHTMLAttributes,
+  type ReactElement,
+} from 'react';
 import { ensureAppRoot } from './pathUtils';
 
 // =============================================================================