Test cases for biometric login and MPIN fallback

1. Sign in with the MPIN or password
2. Turn on fingerprint login when offered, or in app settings, and touch the sensor
3. Close the app from recent apps and reopen it
4. Touch the sensor with the enrolled finger

Expected: The app shows the fingerprint prompt on reopening and opens the home screen on a match. Settings show fingerprint login as on.

Why a real phone: Needs a real fingerprint sensor and the phone's hardware-backed key storage.

1. On an iPhone with Face ID, turn on biometric login in the app
2. Allow the Face ID permission when asked
3. Close and reopen the app and look at the phone
4. Repeat on an iPhone or iPad with Touch ID

Expected: The permission prompt explains why the app uses Face ID, and the app opens on a match. The settings label says Face ID or Touch ID to match the device.

Why a real phone: Face ID and Touch ID matching need a real iPhone's sensors.

1. Keep biometric login off in app settings
2. Close and reopen the app
3. Enter the correct MPIN

Expected: The MPIN screen appears instead of a biometric prompt, and the correct MPIN opens the home screen.

1. Reopen the app with biometric login on
2. Tap Use MPIN on the prompt
3. Reopen the app again and tap Cancel or press Back on the prompt

Expected: Both choices open the MPIN screen and the correct MPIN signs in. The prompt does not reappear in a loop or close the app.

1. Use a build that offers the phone's PIN or pattern as a fallback
2. On the prompt, choose to use the phone's screen lock
3. Enter the phone's PIN or pattern

Expected: The system screen-lock check opens the app on the correct PIN or pattern. A wrong entry counts toward the phone's own limit, not the app's MPIN attempts.

1. Open app settings and turn biometric login off
2. Close and reopen the app

Expected: The app asks for the MPIN, not a fingerprint or face, and the setting stays off after reopening.

1. Start MPIN set-up and enter all same digits, such as 1111
2. Enter a simple sequence, such as 1234
3. Enter a valid MPIN and a different value to confirm

Expected: Repeated and sequential PINs are refused with a reason, and a mismatched confirmation shows an error. No MPIN is saved until a valid PIN is entered twice.

1. On the MPIN screen, enter wrong MPINs until the configured limit is reached
2. Enter the correct MPIN
3. Reinstall the app and try again

Expected: The correct MPIN no longer opens the app once the limit is reached, and the message offers a reset with OTP or full sign-in. Reinstalling does not clear the block.

1. Tap Forgot MPIN on the MPIN screen
2. Verify with the OTP sent to the registered number
3. Set and confirm a new MPIN, then reopen the app

Expected: The new MPIN opens the app and the old MPIN is refused.

1. Open app settings and switch biometric login on
2. Enter a wrong MPIN when asked
3. Switch it on again and enter the correct MPIN

Expected: With the wrong MPIN, biometric login stays off. With the correct MPIN, the prompt appears and biometric login turns on after a match.

1. On an iPhone, turn on biometric login in the app
2. Tap Don't Allow on the Face ID permission prompt
3. Close and reopen the app

Expected: The app explains that Face ID is off for it and how to allow it in Settings, and falls back to the MPIN. It does not show a broken prompt or a blank screen.

1. Remove all fingerprints and face data in phone Settings
2. Open app settings and try to turn on biometric login

Expected: The option is disabled or explains that a fingerprint or face must be added in phone Settings first. The app keeps using the MPIN.

1. Turn on fingerprint login in the app
2. In phone Settings, add a new fingerprint, or an alternate Face ID appearance on iPhone
3. Reopen the app

Expected: The app asks for the MPIN or password and explains that biometric settings changed. Biometric login works again only after the user turns it back on.

Why a real phone: Key invalidation on new enrolment depends on the phone's hardware keystore, which varies by maker.

1. Turn on fingerprint login in the app
2. Delete every fingerprint in phone Settings, keeping the screen lock
3. Reopen the app

Expected: The app opens the MPIN screen without a crash, and app settings show biometric login as off or unavailable.

Why a real phone: How stored keys react to deleted fingerprints differs across OEM hardware keystores.

1. Turn on biometric login in the app
2. In phone Settings, set the screen lock to None or Swipe
3. Reopen the app

Expected: The app opens the MPIN screen without crashing and says biometric login needs a screen lock. After the screen lock and a fingerprint are set again, the user can turn it back on.

Why a real phone: Removing the screen lock deletes hardware-backed keys on a real phone.

1. Reopen the app with biometric login on
2. Touch the sensor with an unenrolled finger until the prompt says too many attempts
3. Use the MPIN, then lock and unlock the phone with its PIN
4. Reopen the app

Expected: The app moves to the MPIN screen with a clear message and does not count these touches as wrong MPINs. Once the phone is unlocked with its PIN, biometric login works again.

Why a real phone: Lockout counts and timing come from the phone's real biometric hardware and OEM firmware.

1. Turn on biometric login on the old phone
2. Move apps and data to a new phone with the phone maker's transfer tool
3. Open the app on the new phone

Expected: The app asks for full sign-in or the MPIN, and biometric login is off until turned on again. It does not show biometric login as on and then fail or crash.

Why a real phone: Needs two real phones and the maker's transfer tool, which moves app data but not keys.

1. Reopen the app so the biometric prompt shows
2. Rotate the phone, then open the app in split screen
3. Touch the sensor

Expected: The prompt stays or comes back once, and a match opens the app. The app is not left on a blank screen with no prompt.

1. Reopen the app so the biometric prompt shows
2. Answer an incoming call, or press the power button
3. End the call or unlock the phone, and return to the app

Expected: The app shows the prompt again or the MPIN screen. The interruption is not counted as a failed attempt.

Why a real phone: Needs the real biometric prompt and a carrier call on an OEM skin.

1. With biometric login on, start a payment that opens a UPI app
2. Approve the payment in the UPI app
3. Return to the app

Expected: The payment status shows straight away, or right after the biometric check if the app asks for one. The user is not sent to the home screen without the result or asked to pay again.

Why a real phone: Needs switching to a real installed UPI app and back.

1. Open the app with biometric login
2. Switch to another app briefly, then return
3. Leave it in the background longer than the configured time, then return

Expected: A quick switch returns to the same screen without a prompt. After the configured time, the prompt appears before any account data shows.

1. Turn on airplane mode
2. Reopen the app and pass the biometric prompt
3. Turn airplane mode off

Expected: The app shows a clear offline state or cached screens, then loads fresh data once online. It does not loop back to the prompt or sign the user out.

1. On a budget phone whose face unlock uses only the front camera, set up face unlock
2. Open app settings and try to turn on face login
3. If it turns on, hold up a printed photo of the enrolled face

Expected: The app offers fingerprint or MPIN instead of weak face unlock, or explains that this face unlock is not secure enough. A photo cannot open the app.

Why a real phone: Weak 2D face unlock exists only on certain budget phones' hardware.

1. On each phone, reopen the app with fingerprint login on
2. Check the prompt's title, text and Use MPIN button
3. Pass once, then fail once and choose Use MPIN

Expected: Each prompt shows the app's title and the Use MPIN option, and each choice leads to the right screen. No phone shows a second, app-drawn dialog on top of the system prompt.

Why a real phone: Each OEM skin draws and handles the system biometric prompt in its own way.

1. On a phone with an in-display sensor, reopen the app
2. Look for the sensor icon on the prompt
3. Touch the icon with the enrolled finger

Expected: The sensor icon shows at the sensor's position and nothing from the app covers it. A touch on the icon opens the app.

Why a real phone: In-display sensors and their on-screen icon exist only on real phones.

1. Turn on the phone's built-in app lock for this app
2. Keep the app's own biometric login on
3. Reopen the app and pass both checks

Expected: The two checks appear one after the other and the app opens. Neither prompt cancels the other or sends the user into a loop.

Why a real phone: Built-in app lockers are OEM features on Xiaomi, Vivo, Oppo and Realme phones.

1. Turn on biometric login on the current store version
2. Update the app to the new build from the Play Store testing track
3. Reopen the app and use biometric login

Expected: Biometric login still works after the update without turning it on again. The app does not crash or ask for full sign-in.

1. Turn on biometric login for account A, then sign out
2. Reopen the app and sign in as account B
3. Close and reopen the app

Expected: After sign-out, no biometric prompt opens account A. Account B starts with biometric login off and must turn it on with its own MPIN.

1. Turn on biometric login on phone A
2. From phone B or the website, sign out of all devices
3. Reopen the app on phone A and pass the biometric prompt

Expected: After the match, the app shows a signed-out message and asks for full sign-in. No account data from the ended session is shown.

1. Enrol a second person's fingerprint in phone Settings
2. Turn on fingerprint login in the app
3. Read the message shown while turning it on

Expected: Before it turns on, the app warns that any fingerprint saved on the phone will be able to open the account.

1. Open an account screen, then press Home
2. Wait past the configured lock time and open the recent apps screen
3. Look at the app's thumbnail

Expected: The thumbnail shows a blank, blurred or logo screen, not balances or personal data.

1. Turn on TalkBack and reopen the app
2. Move through the prompt, then choose Use MPIN
3. Enter the MPIN with TalkBack's double-tap

Expected: The prompt's title and buttons are read out, and each keypad key is read by its digit. Entered MPIN digits are announced as dots, not spoken aloud.

1. Set font size and display size to the largest in phone Settings
2. Open the MPIN screen and the biometric settings page

Expected: The keypad, labels and errors fit without being cut off. Forgot MPIN and the fingerprint option remain visible and tappable.

1. Set the app language to Hindi
2. Reopen the app to see the biometric prompt
3. Choose Use MPIN and enter a wrong MPIN

Expected: The prompt title, Use MPIN option and error messages show in Hindi without truncation. The keypad keeps digits 0–9 unless the app offers other numerals.