Tell us about cases of reconnection checks in a mobile application.

Reconnection tests verify how a mobile application behaves when losing and subsequently restoring a connection to a server or other network resources.

Test scenarios:

• Network switching:
  • Wi-Fi -> Mobile internet (LTE/5G).
  • Mobile internet (LTE/5G) -> Wi-Fi.
  • Wi-Fi (one access point) -> Wi-Fi (another access point).
• Signal loss:
  • Entering a coverage zone without signal (elevator, metro).
  • Enabling/disabling "Airplane mode".
  • Forcibly disabling network interfaces (Wi-Fi, Cellular Data) through device settings.
• Server issues:
  • Temporary API unavailability.
  • Server reboot.
  • Network delays (simulated with proxy servers).

What we check:

• UI/UX behavior:
  • Displaying loading indicators or errors.
  • Preserving current user state (e.g., incomplete input, list position).
  • Correctly displaying notifications about connection loss/restoration.
  • No application crashes or "hangs".
• Data integrity:
  • Data in the process of sending/receiving during disconnection should be correctly handled after restoration.
  • Locally stored data should synchronize with the server.
• Retry logic:
  • The app should have retry logic with exponential backoff.
  • Limits on retry count and wait time.
• Session handling:
  • User session should be preserved or correctly restored without forced logout.

Tools and techniques:

• Network proxies: Charles Proxy, Fiddler. Used to simulate delays, packet drops, request blocking.
• Network utilities: Developer tools in browsers (for WebView), specialized mobile traffic control utilities.
• "Airplane mode": A simple way to simulate complete connection loss.
• Disabling network interfaces: Through device system settings.
• Network emulators: Tools to simulate various network conditions (speed, delay, packet loss).
• Automation: Using Appium, Espresso (Android), XCUITest (iOS) for automating network switching scenarios or calling system functions (enabling/disabling Airplane Mode).

// Example of automating reconnection test with Appium (Python)

from appium import webdriver
import time

desired_caps = {
    'platformName': 'Android',
    'deviceName': 'Android Emulator', # Or real device
    'appPackage': 'com.yourapp.package',
    'appActivity': 'com.yourapp.MainActivity',
    'automationName': 'UiAutomator2'
}

driver = webdriver.Remote('http://localhost:4723/wd/hub', desired_caps)

try:
    // Perform actions requiring network
    driver.find_element_by_accessibility_id("some_button").click()
    time.sleep(5) # Wait for data to load

    // Enable "Airplane mode"
    driver.open_notifications()
    driver.find_element_by_accessibility_id("Airplane mode").click()
    driver.back() # Close notifications
    print("Airplane mode ON")
    time.sleep(10) # Wait for connection loss

    // Attempt a network action
    driver.find_element_by_accessibility_id("another_button").click()
    // Check for error/no network indicator

    // Disable "Airplane mode"
    driver.open_notifications()
    driver.find_element_by_accessibility_id("Airplane mode").click()
    driver.back() # Close notifications
    print("Airplane mode OFF")
    time.sleep(10) # Wait for connection restoration

    // Verify functionality and data correctness
    // ... assert statements ...

except Exception as e:
    print(f"Error: {e}")

finally:
    driver.quit()

Reconnection testing is critical for ensuring the stability and reliability of a mobile application under unstable network conditions.