In-Memory File System with Search

Design an in-memory file system with the following operations: mkdir /path: Create a path. addContentToFile /path/file content: Add content to a file. readContentFromFile /path/file: Read content from a file. ls /path: List the directory including files and subdirectories. searchUsers: Search for users. Implement these functions based in memory, ensuring efficiency. Provide comprehensive unit test cases for testing.