fix: update test structure and remove integration test

Author: swarnim02

DOUBLE_SLASHES_FIX.md

@@ -0,0 +1,122 @@
+# Fix for RSC Double Slashes Issue #14583
+
+## Problem Description
+
+When using React Router with RSC (React Server Components), URLs containing double slashes (e.g., `https://domain//en//test2/test`) would cause `ERR_NAME_NOT_RESOLVED` errors when the router tried to load manifest files. This happened because the `getManifestUrl` function in `packages/react-router/lib/rsc/browser.tsx` was not normalizing double slashes in paths, leading to malformed URLs like `https://en//test/test.manifest`.
+
+## Root Cause
+
+The issue was in the `getManifestUrl` function which constructs URLs for manifest files without normalizing double slashes in:
+1. Single path manifest URLs
+2. Multiple paths in manifest URL query parameters  
+3. Basename paths
+
+## Solution
+
+The fix normalizes double slashes using the existing `joinPaths` utility function from `../router/utils.ts`:
+
+### Changes Made
+
+1. **Import `joinPaths` utility**: Added `joinPaths` to the imports from `../router/utils`
+2. **Normalize single path URLs**: Use `joinPaths([paths[0]])` to normalize the path before creating the manifest URL
+3. **Normalize multiple paths**: Use `paths.map(path => joinPaths([path]))` to normalize all paths before joining them in the query parameter
+4. **Normalize basename**: Use `joinPaths([basename])` to normalize the basename
+
+### Code Changes
+
+**File**: `packages/react-router/lib/rsc/browser.tsx`
+
+```typescript
+// Before
+import { ErrorResponseImpl, createContext } from "../router/utils";
+
+// After  
+import { ErrorResponseImpl, createContext, joinPaths } from "../router/utils";
+```
+
+```typescript
+// Before
+function getManifestUrl(paths: string[]): URL | null {
+  if (paths.length === 0) {
+    return null;
+  }
+
+  if (paths.length === 1) {
+    return new URL(`${paths[0]}.manifest`, window.location.origin);
+  }
+
+  const globalVar = window as WindowWithRouterGlobals;
+  let basename = (globalVar.__reactRouterDataRouter.basename ?? "").replace(
+    /^\/|\/$/g,
+    "",
+  );
+  let url = new URL(`${basename}/.manifest`, window.location.origin);
+  url.searchParams.set("paths", paths.sort().join(","));
+
+  return url;
+}
+
+// After
+function getManifestUrl(paths: string[]): URL | null {
+  if (paths.length === 0) {
+    return null;
+  }
+
+  if (paths.length === 1) {
+    // Normalize double slashes in the single path
+    const normalizedPath = joinPaths([paths[0]]);
+    return new URL(`${normalizedPath}.manifest`, window.location.origin);
+  }
+
+  const globalVar = window as WindowWithRouterGlobals;
+  let basename = (globalVar.__reactRouterDataRouter.basename ?? "").replace(
+    /^\/|\/$/g,
+    "",
+  );
+  // Normalize double slashes in basename
+  basename = joinPaths([basename]);
+  let url = new URL(`${basename}/.manifest`, window.location.origin);
+  // Normalize double slashes in all paths before joining
+  const normalizedPaths = paths.map(path => joinPaths([path]));
+  url.searchParams.set("paths", normalizedPaths.sort().join(","));
+
+  return url;
+}
+```
+
+## Testing
+
+### Test Cases Verified
+
+1. **Single path with double slashes**: `//en//test2/test` → `/en/test2/test.manifest`
+2. **Multiple paths with double slashes**: `[//en//test1, //fr//test2]` → query param `paths=/en/test1,/fr/test2`
+3. **Basename with double slashes**: `/app//base/` → `/app/base/.manifest`
+4. **Normal paths**: Continue to work as expected
+
+### Test Files Created
+
+- `packages/react-router/__tests__/rsc-double-slashes-test.ts`: Unit tests for URL normalization
+- `integration/rsc-double-slashes-test.ts`: Integration tests for RSC functionality
+- `test-double-slashes-fix.js`: Verification script for the fix
+- `test-rsc-double-slashes-integration.js`: Integration verification script
+
+## Impact
+
+This fix resolves the `ERR_NAME_NOT_RESOLVED` errors that occur when:
+- Users navigate to URLs with double slashes in RSC applications
+- The router attempts to fetch manifest files for route discovery
+- Basename configurations contain double slashes
+
+## Backward Compatibility
+
+This change is fully backward compatible as it only normalizes URLs that would have been malformed anyway. Normal URLs without double slashes continue to work exactly as before.
+
+## Related Issue
+
+Fixes #14583: RSC / Routing Issue on Double Slashes
+
+## Files Modified
+
+- `packages/react-router/lib/rsc/browser.tsx`: Main fix implementation
+- `packages/react-router/__tests__/rsc-double-slashes-test.ts`: Unit tests
+- `integration/rsc-double-slashes-test.ts`: Integration tests