# Hold'em dealer tests

Unit tests for the money logic behind `/Casino/TexasHoldem` — the betting engine, the
side-pot calculator, the split calculator and the table state.

```bash
node --test tests/holdem/*.test.js
```

No install step, no `package.json`, no dependencies. The browser modules are plain
script-tag files that each end with a `module.exports` guard, so Node can require them
as-is; `load.js` puts them on `globalThis` under the same names they use to find each
other in the page, in the load order from `TexasHoldem.cshtml`.

## What's covered

| File | Covers |
| --- | --- |
| `potCalculator.test.js` | Main and side pots, dead money, uncalled bets, odd-cent distribution |
| `betting.test.js` | Blinds, street completion, raises reopening the action, all-in run-outs |
| `state.test.js` | Button rotation, which seats post blinds, session standings |
| `splitCalculator.test.js` | Chopped pots, odd chips, unmakeable denominations |
| `invariants.test.js` | 1000 randomised hands per property (see below) |

## The layout audit

The unit tests above cover the money. `uiAudit.js` covers the thing you can only see
in a browser: whether a dealer can actually reach every control.

```bash
node tests/holdem/runUiAudit.js          # needs Playwright and the site running
```

It checks WCAG AA contrast, touch target sizes, touch-action and tap highlights, that fields stay selectable and are large
enough not to trigger iOS zoom, that nothing important is covered or off-screen with
no way to scroll to it, that no grid column has collapsed to nothing, and that no
text is painted outside its box. It runs over the table, all five overlays and Quick
Split, at thirteen viewports from a 360px phone to a 1600px desktop and the same
phones on their side.

Deliberately not in CI: the unit suite is dependency-free and runs in a second, while
this one needs a browser and a running site. Run it after any change that adds or
resizes a control. With no Playwright to hand, paste `uiAudit.js` into devtools and
call `LayoutAudit.runAll()`.

The contrast check is built so it cannot report a false positive: backgrounds
composite through alpha, and where a gradient is involved every colour stop is tried
and the most flattering one used. A finding means the text fails even under the
reading most generous to it. Two earlier attempts at this got it wrong in both
directions — one read only `background-color` and scored text on a gradient against
nothing, the other treated low-alpha stops as opaque — so `uiAudit.js` is checked
against known-answer cases before it is believed.

Touch targets are measured by probing outward with `elementFromPoint` rather than by
reading the element box, because the box lies in both directions: a small control can
be padded out with a transparent `::after` and respond well beyond its painted size,
and a checkbox inside a label is hit by tapping the label. The 44px rule is only
enforced where `hover: none` says there's no mouse.

It exists because these checks were being re-typed into a console every time
something changed, and each time they only covered whatever had just been touched.
That is how the standings table shipped with a player-name column zero pixels wide
and kept it for two rounds.

## Why the randomised suite exists

Every correctness bug found in this tool so far has been shape-dependent: blinds posted
to empty chairs, the button skipping past players, heads-up acting out of order, an
overbet announced as a side pot. None of them show up on a full six-handed table with
equal stacks, which is the table anyone writes a fixed example for.

`invariants.test.js` deals a thousand hands across random seat counts, random empty
chairs, random stack depths and random dealer input, and checks the things a dealer
would notice being wrong:

- chips are never created or destroyed during play
- the pot breakdown plus the uncalled returns always equal the money that went in
- paying the pot out settles it to the cent
- once uncalled chips are handed back, nobody is still betting above the whole table
- the button and both blinds always land on players who are actually in the hand

The generator is seeded, so a failure reproduces from the seed printed in the message
rather than being a flake to re-run.