testsAndMisc/python_pkg/android_ui/README.md
Krzysztof kuhy Rudnicki b73811c233
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Add android_ui: drive Android apps by element, never by coordinates
Shared across every repo with an Android surface (screen-locker's workout_app,
todo, dufs-cloud/app). Works against a plain release APK on a physical device
over adb — no root, no emulator, no Flutter debug connection, no app changes.

Driving an app by tapping pixel positions read off a screenshot fails in ways
that look like success. All observed in one session (2026-08-10) verifying
workout_app's Firebase restore:

* A tap aimed at a password field landed with the field unfocused. The typed
  password went nowhere and NOTHING errored — the next screenshot just showed
  an empty box. type_into/type_into_field now re-read the field and raise.
* Opening the soft keyboard moved a field from y=1572 to y=1319, so a
  coordinate captured one step earlier was already wrong. Every action
  re-resolves the element immediately before acting.
* A widget behind the keyboard reports its LAID-OUT position (1549) not its
  real one (1939) — a 390px error that taps a letter key and reports success.
  keyboard_is_up() distinguishes "absent" from "behind the keyboard", and tap
  closes the keyboard first.
* KEYCODE_BACK is a route pop in Flutter, not a keyboard dismiss: it navigated
  out of Settings and discarded typed credentials, twice. dismiss_keyboard
  tries ESCAPE then BACK and verifies via dumpsys input_method.
* `input text` inserts at the cursor, so typing over a filled field produced
  "canary@example.com321krzychu@gmail.com". Fields are cleared first.
* uiautomator returns ONLY the focused EditText nodes while a Flutter text
  field has focus, and stays that way across retries — so a naive retry loop
  never converges. Partial trees are retried and the best result kept.
* An EMPTY EditText has no text, content-desc or resource-id, so a
  "must be labelled" filter drops the very field you need to fill in. Editable
  nodes are kept regardless and addressable by position.

Ambiguity is an error rather than a silent first-match: `tap "Back"` correctly
refuses when "OFFLINE BACKUP" is also on screen.

Its own test suite caught a real bug in _escape: backslash sat inside the
escape loop, so "&" became "\\&" and a password containing shell
metacharacters would have been typed wrong.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JupKvZCNKRmEeRQY3G1unG
2026-08-10 17:01:28 +02:00

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# android_ui — drive Android apps by element, never by coordinates
Shared across every repo with an Android surface (`~/screen-locker`'s
workout_app, `~/todo`, `~/dufs-cloud/app`). Works against a plain release APK
on a physical device over `adb` — no root, no emulator, no Flutter debug
connection, no change to app source.
## Why
Driving an app by tapping pixel positions read off a screenshot fails in ways
that look like success. All of these were observed in one session
(2026-08-10), verifying the workout app's Firebase restore:
| Failure | What it looks like |
| ------------------------------- | -------------------------------------------------------------------------------------------------------------- |
| Tap lands on an unfocused field | Typed text goes nowhere; nothing errors; the next screenshot shows an empty box |
| Soft keyboard opens | A field moves 1572 → 1319; every coordinate captured a step earlier is wrong |
| Widget sits behind the keyboard | The tree reports its _laid-out_ position (1549) not its real one (1939) — a 390px error that taps a letter key |
| Screenshot scaling | The harness renders 1080×2400 at 900×2000, so every read coordinate needs a manual ×1.2 |
| Typing into a filled field | `input text` inserts at the cursor: `old@example.comnew@example.com` |
Two device quirks are handled rather than documented, because both produced
false results before they were understood:
- `uiautomator dump` returns **only the `EditText` nodes** while a Flutter text
field holds focus. The button you are about to tap is simply missing, and it
stays missing across retries — a naive retry loop never converges.
- `KEYCODE_BACK` is a **route pop** in Flutter, not a keyboard dismiss. It
navigates out of the screen and discards typed input.
## Use
```bash
export PYTHONPATH=~/testsAndMisc
python3 -m python_pkg.android_ui dump
python3 -m python_pkg.android_ui find "Connect Firebase"
python3 -m python_pkg.android_ui --exact tap "Back"
python3 -m python_pkg.android_ui wait "Connected." --timeout 30
python3 -m python_pkg.android_ui focus
```
Every subcommand exits non-zero and names the query on failure, so a script can
tell a real failure from a successful no-op.
```python
from python_pkg.android_ui import AndroidUi
ui = AndroidUi() # or AndroidUi(serial="23181JEGR08034")
ui.tap("Connect Firebase", exact=True)
ui.type_into_field(0, "kuhy@example.com") # verifies the field changed
ui.wait_for("Connected.", timeout=30)
```
## Guarantees
- **Ambiguity is an error.** A query matching 0 or >1 elements raises; it never
silently acts on the first match. (`tap "Back"` correctly refuses when
"OFFLINE BACKUP" is also on screen — use `--exact`.)
- **Coordinates are never reused.** Every action re-reads the tree immediately
before acting, and `tap` closes the keyboard first when one is up.
- **Typing is verified.** `type_into` / `type_into_field` re-read the field and
raise if the contents did not change. They clear before typing, so a filled
field is replaced, not appended to.
- **Empty fields are findable.** An empty `EditText` has no text, content-desc
or resource-id; it is kept anyway, addressable by position via
`editable_fields()` / `type_into_field(index, …)`.
- **Partial trees are retried,** and `keyboard_is_up()` distinguishes "element
absent" from "element behind the keyboard".
## Known gaps
- A widget with no accessibility label cannot be targeted at all. The workout
app's Settings gear is one — that is an a11y bug in the app, and this tool
surfacing it is the point. Add a `Semantics(label: …)` and it becomes
addressable.
- Scrolling is not yet modelled: a widget outside the viewport is not in the
tree. Scroll with `adb shell input swipe` first, or add `scroll_to()`.