Restore backend state when Playwright test finishes (#1168)

* Restore backend state when Playwright test finishes. Resolve #1094

* Add warning when env var not set

* Rename and replace with scaffolding option for models dir

* Rename

* Define another env var [skip ci]

* Fix paths [skip ci]

* Update README.md

---------

Co-authored-by: Chenlei Hu <huchenlei@proton.me>

browser_tests/utils/backupUtils.ts

@@ -0,0 +1,69 @@
+import path from 'path'
+import fs from 'fs-extra'
+
+type PathParts = readonly [string, ...string[]]
+
+const getBackupPath = (originalPath: string): string => `${originalPath}.bak`
+
+const resolvePathIfExists = (pathParts: PathParts): string | null => {
+  const resolvedPath = path.resolve(...pathParts)
+  if (!fs.pathExistsSync(resolvedPath)) {
+    console.warn(`Path not found: ${resolvedPath}`)
+    return null
+  }
+  return resolvedPath
+}
+
+const createScaffoldingCopy = (srcDir: string, destDir: string) => {
+  // Get all items (files and directories) in the source directory
+  const items = fs.readdirSync(srcDir, { withFileTypes: true })
+
+  for (const item of items) {
+    const srcPath = path.join(srcDir, item.name)
+    const destPath = path.join(destDir, item.name)
+
+    if (item.isDirectory()) {
+      // Create the corresponding directory in the destination
+      fs.ensureDirSync(destPath)
+
+      // Recursively copy the directory structure
+      createScaffoldingCopy(srcPath, destPath)
+    }
+  }
+}
+
+export function backupPath(
+  pathParts: PathParts,
+  { renameAndReplaceWithScaffolding = false } = {}
+) {
+  const originalPath = resolvePathIfExists(pathParts)
+  if (!originalPath) return
+
+  const backupPath = getBackupPath(originalPath)
+  try {
+    if (renameAndReplaceWithScaffolding) {
+      // Rename the original path and create scaffolding in its place
+      fs.moveSync(originalPath, backupPath)
+      createScaffoldingCopy(backupPath, originalPath)
+    } else {
+      // Create a copy of the original path
+      fs.copySync(originalPath, backupPath)
+    }
+  } catch (error) {
+    console.error(`Failed to backup ${originalPath} from ${backupPath}`, error)
+  }
+}
+
+export function restorePath(pathParts: PathParts) {
+  const originalPath = resolvePathIfExists(pathParts)
+  if (!originalPath) return
+
+  const backupPath = getBackupPath(originalPath)
+  if (!fs.pathExistsSync(backupPath)) return
+
+  try {
+    fs.moveSync(backupPath, originalPath, { overwrite: true })
+  } catch (error) {
+    console.error(`Failed to restore ${originalPath} from ${backupPath}`, error)
+  }
+}