feat(js): m05 game and m06 view with fixtures and tests

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
This commit is contained in:
Lucas Winther
2026-10-28 23:45:10 +01:00
co-authored by Claude Sonnet 5.5
parent 08b462d5cc
commit b83f94894e
12 changed files with 1398 additions and 0 deletions
+189
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@@ -0,0 +1,189 @@
{
"function": "tick",
"cases": [
{
"name": "eat-then-respawn",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 1,
"y": 0
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 1,
"y": 0
},
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 1,
"y": 1
},
"seed": 1831565813,
"score": 1,
"status": "Playing",
"frame": 0
}
},
{
"name": "plain-move-no-respawn",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 1,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
}
},
{
"name": "wall-hit-is-game-over-no-spawn",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 2,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 0,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 2,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 0,
"y": 1
},
"seed": 0,
"score": 0,
"status": "GameOver",
"frame": 0
}
},
{
"name": "game-over-state-unchanged",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "GameOver",
"frame": 0
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "GameOver",
"frame": 0
}
}
]
}
+172
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{
"function": "history",
"cases": [
{
"name": "no-actions-gives-just-the-start",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
[]
],
"expected": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
}
]
},
{
"name": "every-intermediate-state-is-kept",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
[
{
"tag": "Turn",
"dir": "Down"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
}
]
],
"expected": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Down",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 1
}
],
"dir": "Down",
"nextDir": "Down",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 1
}
],
"dir": "Down",
"nextDir": "Down",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "GameOver",
"frame": 0
}
]
}
]
}
+172
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{
"function": "replay",
"cases": [
{
"name": "twelve-actions-eat-one-apple",
"args": [
{
"width": 20,
"height": 20,
"snake": [
{
"x": 10,
"y": 10
},
{
"x": 9,
"y": 10
},
{
"x": 8,
"y": 10
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 1,
"y": 9
},
"seed": 1831565855,
"score": 0,
"status": "Playing",
"frame": 0
},
[
{
"tag": "Turn",
"dir": "Up"
},
{
"tag": "Tick"
},
{
"tag": "Turn",
"dir": "Left"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
},
{
"tag": "Tick"
}
]
],
"expected": {
"width": 20,
"height": 20,
"snake": [
{
"x": 1,
"y": 9
},
{
"x": 2,
"y": 9
},
{
"x": 3,
"y": 9
},
{
"x": 4,
"y": 9
}
],
"dir": "Left",
"nextDir": "Left",
"apple": {
"x": 6,
"y": 5
},
"seed": 3663131668,
"score": 1,
"status": "Playing",
"frame": 0
}
},
{
"name": "no-actions-returns-the-start",
"args": [
{
"width": 20,
"height": 20,
"snake": [
{
"x": 10,
"y": 10
},
{
"x": 9,
"y": 10
},
{
"x": 8,
"y": 10
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 1,
"y": 9
},
"seed": 1831565855,
"score": 0,
"status": "Playing",
"frame": 0
},
[]
],
"expected": {
"width": 20,
"height": 20,
"snake": [
{
"x": 10,
"y": 10
},
{
"x": 9,
"y": 10
},
{
"x": 8,
"y": 10
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 1,
"y": 9
},
"seed": 1831565855,
"score": 0,
"status": "Playing",
"frame": 0
}
}
]
}
+348
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{
"function": "update",
"cases": [
{
"name": "tick-moves-the-snake",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
{
"tag": "Tick"
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 1,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
}
},
{
"name": "tick-eating-respawns-apple",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 1,
"y": 0
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
{
"tag": "Tick"
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 1,
"y": 0
},
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 1,
"y": 1
},
"seed": 1831565813,
"score": 1,
"status": "Playing",
"frame": 0
}
},
{
"name": "tick-into-wall-is-game-over",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 2,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 0,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
{
"tag": "Tick"
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 2,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 0,
"y": 1
},
"seed": 0,
"score": 0,
"status": "GameOver",
"frame": 0
}
},
{
"name": "tick-while-paused-does-nothing",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Paused",
"frame": 0
},
{
"tag": "Tick"
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Paused",
"frame": 0
}
},
{
"name": "turn-sets-next-dir",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
{
"tag": "Turn",
"dir": "Down"
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Down",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
}
},
{
"name": "turn-against-direction-is-ignored",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
},
{
"tag": "Turn",
"dir": "Left"
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Playing",
"frame": 0
}
},
{
"name": "turn-while-paused-is-ignored",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Paused",
"frame": 0
},
{
"tag": "Turn",
"dir": "Down"
}
],
"expected": {
"width": 3,
"height": 2,
"snake": [
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 0,
"status": "Paused",
"frame": 0
}
}
]
}
+398
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{
"function": "view",
"cases": [
{
"name": "playing-with-apple",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 1,
"y": 0
},
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 5,
"status": "Playing",
"frame": 0
}
],
"expected": [
{
"tag": "Rect",
"x": 0,
"y": 0,
"w": 60,
"h": 40,
"color": "#111111"
},
{
"tag": "Rect",
"x": 41,
"y": 21,
"w": 18,
"h": 18,
"color": "#e53935"
},
{
"tag": "Rect",
"x": 21,
"y": 1,
"w": 18,
"h": 18,
"color": "#7cb342"
},
{
"tag": "Rect",
"x": 1,
"y": 1,
"w": 18,
"h": 18,
"color": "#43a047"
},
{
"tag": "Text",
"x": 6,
"y": 18,
"text": "Score: 5",
"color": "#ffffff",
"size": 16,
"align": "left"
}
]
},
{
"name": "playing-without-apple-has-no-apple-rect",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 1,
"y": 0
},
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": null,
"seed": 0,
"score": 5,
"status": "Playing",
"frame": 0
}
],
"expected": [
{
"tag": "Rect",
"x": 0,
"y": 0,
"w": 60,
"h": 40,
"color": "#111111"
},
{
"tag": "Rect",
"x": 21,
"y": 1,
"w": 18,
"h": 18,
"color": "#7cb342"
},
{
"tag": "Rect",
"x": 1,
"y": 1,
"w": 18,
"h": 18,
"color": "#43a047"
},
{
"tag": "Text",
"x": 6,
"y": 18,
"text": "Score: 5",
"color": "#ffffff",
"size": 16,
"align": "left"
}
]
},
{
"name": "paused-overlay",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 1,
"y": 0
},
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": {
"x": 2,
"y": 1
},
"seed": 0,
"score": 5,
"status": "Paused",
"frame": 0
}
],
"expected": [
{
"tag": "Rect",
"x": 0,
"y": 0,
"w": 60,
"h": 40,
"color": "#111111"
},
{
"tag": "Rect",
"x": 41,
"y": 21,
"w": 18,
"h": 18,
"color": "#e53935"
},
{
"tag": "Rect",
"x": 21,
"y": 1,
"w": 18,
"h": 18,
"color": "#7cb342"
},
{
"tag": "Rect",
"x": 1,
"y": 1,
"w": 18,
"h": 18,
"color": "#43a047"
},
{
"tag": "Text",
"x": 6,
"y": 18,
"text": "Score: 5",
"color": "#ffffff",
"size": 16,
"align": "left"
},
{
"tag": "Text",
"x": 30,
"y": 20,
"text": "Paused",
"color": "#ffffff",
"size": 32,
"align": "center"
},
{
"tag": "Text",
"x": 30,
"y": 50,
"text": "Press Space to resume",
"color": "#ffffff",
"size": 16,
"align": "center"
}
]
},
{
"name": "game-over-overlay-on-20x20-board",
"args": [
{
"width": 20,
"height": 20,
"snake": [
{
"x": 10,
"y": 10
},
{
"x": 9,
"y": 10
},
{
"x": 8,
"y": 10
}
],
"dir": "Right",
"nextDir": "Right",
"apple": null,
"seed": 1,
"score": 0,
"status": "GameOver",
"frame": 0
}
],
"expected": [
{
"tag": "Rect",
"x": 0,
"y": 0,
"w": 400,
"h": 400,
"color": "#111111"
},
{
"tag": "Rect",
"x": 201,
"y": 201,
"w": 18,
"h": 18,
"color": "#7cb342"
},
{
"tag": "Rect",
"x": 181,
"y": 201,
"w": 18,
"h": 18,
"color": "#43a047"
},
{
"tag": "Rect",
"x": 161,
"y": 201,
"w": 18,
"h": 18,
"color": "#43a047"
},
{
"tag": "Text",
"x": 6,
"y": 18,
"text": "Score: 0",
"color": "#ffffff",
"size": 16,
"align": "left"
},
{
"tag": "Text",
"x": 200,
"y": 200,
"text": "Game Over",
"color": "#ffffff",
"size": 32,
"align": "center"
},
{
"tag": "Text",
"x": 200,
"y": 230,
"text": "Press R to restart",
"color": "#ffffff",
"size": 16,
"align": "center"
}
]
},
{
"name": "won-overlay",
"args": [
{
"width": 3,
"height": 2,
"snake": [
{
"x": 1,
"y": 0
},
{
"x": 0,
"y": 0
}
],
"dir": "Right",
"nextDir": "Right",
"apple": null,
"seed": 0,
"score": 5,
"status": "Won",
"frame": 0
}
],
"expected": [
{
"tag": "Rect",
"x": 0,
"y": 0,
"w": 60,
"h": 40,
"color": "#111111"
},
{
"tag": "Rect",
"x": 21,
"y": 1,
"w": 18,
"h": 18,
"color": "#7cb342"
},
{
"tag": "Rect",
"x": 1,
"y": 1,
"w": 18,
"h": 18,
"color": "#43a047"
},
{
"tag": "Text",
"x": 6,
"y": 18,
"text": "Score: 5",
"color": "#ffffff",
"size": 16,
"align": "left"
},
{
"tag": "Text",
"x": 30,
"y": 20,
"text": "You Win!",
"color": "#ffffff",
"size": 32,
"align": "center"
},
{
"tag": "Text",
"x": 30,
"y": 50,
"text": "Press R to restart",
"color": "#ffffff",
"size": 16,
"align": "center"
}
]
}
]
}
+21
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// m05 game: one `update` function turns every action into a new state; replay is a fold over actions.
import { turn } from './rules.js'
import { tick } from './spawn.js'
/** Tick and Turn are handled here; other actions leave the state alone (m10 adds more). */
export const update = (state, action) => {
switch (action.tag) {
case 'Tick': return tick(state)
case 'Turn': return turn(state, action.dir)
default: return state
}
}
/** Fold the actions over the state, left to right. */
export const replay = (state, actions) => actions.reduce(update, state)
/** Like replay, but keeps each intermediate state. Recursion instead of mutation: no array is ever pushed to. */
export const history = (state, actions) =>
actions.length === 0
? [state]
: [state, ...history(update(state, actions[0]), actions.slice(1))]
+30
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// m06 view: the picture is plain data (a list of shapes); drawing it is somebody else's job (m07).
/** Pixels per board cell. */
export const CELL = 20
const rect = (x, y, w, h, color) => ({ tag: 'Rect', x, y, w, h, color })
const text = (x, y, str, size, align) => ({ tag: 'Text', x, y, text: str, color: '#ffffff', size, align })
// One cell, inset by 1px so neighbouring segments show a gap.
const cell = (p, color) => rect(p.x * CELL + 1, p.y * CELL + 1, CELL - 2, CELL - 2, color)
const overlay = (state) => {
const cx = (state.width * CELL) / 2
const cy = (state.height * CELL) / 2
const banner = (title, hint) => [text(cx, cy, title, 32, 'center'), text(cx, cy + 30, hint, 16, 'center')]
switch (state.status) {
case 'Paused': return banner('Paused', 'Press Space to resume')
case 'GameOver': return banner('Game Over', 'Press R to restart')
case 'Won': return banner('You Win!', 'Press R to restart')
default: return []
}
}
export const view = (state) => [
rect(0, 0, state.width * CELL, state.height * CELL, '#111111'),
...(state.apple === null ? [] : [cell(state.apple, '#e53935')]),
...state.snake.map((p, i) => cell(p, i === 0 ? '#7cb342' : '#43a047')),
text(6, 18, `Score: ${state.score}`, 16, 'left'),
...overlay(state),
]
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import { todo } from './todo.js'
/**
* The one function that says how the game changes: `(state, action) -> state`.
* `Tick` runs a game step (`tick`), `Turn` asks to change direction (`turn`);
* every other action returns the state unchanged for now.
*/
export const update = (state, action) => todo('m05')
/** Apply all actions in order, starting from `state`, and return the final state. */
export const replay = (state, actions) => todo('m05')
/** Like `replay`, but keep every state: `[state, afterFirst, afterSecond, ...]`, so its length is `actions.length + 1`. */
export const history = (state, actions) => todo('m05')
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import { todo } from './todo.js'
/** Pixels per board cell. */
export const CELL = 20
/**
* Describe the picture as data: an array of shapes, drawn in order.
* `{tag:'Rect', x, y, w, h, color}` and `{tag:'Text', x, y, text, color, size, align}`.
* Order: background Rect(0,0,width*CELL,height*CELL,'#111111'); the apple (if any) as
* Rect(ax*CELL+1, ay*CELL+1, CELL-2, CELL-2, '#e53935'); each snake segment in list order, same size,
* head '#7cb342' and body '#43a047'; Text(6,18,'Score: <n>','#ffffff',16,'left');
* then an overlay centred at (width*CELL/2, height*CELL/2), all '#ffffff':
* Paused: 'Paused' (size 32) and, 30px lower, 'Press Space to resume' (size 16);
* GameOver: 'Game Over' + 'Press R to restart'; Won: 'You Win!' + 'Press R to restart'; Playing: none.
* Text in the overlay uses align 'center'.
*/
export const view = (state) => todo('m06')
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@@ -13,6 +13,7 @@ const fixtureTests = (name, f) => {
fixtureTests('m04-free-cells', freeCells)
fixtureTests('m04-spawn', spawnApple)
fixtureTests('m04-new-game', newGame)
fixtureTests('m04-tick', tick)
// 3x2 board, one-cell snake, about to eat the apple at (1,0)
const eating = freeze({
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import test from 'node:test'
import assert from 'node:assert/strict'
import { update, replay, history } from '../src/game.js'
import { loadFixture, freeze } from './helpers.js'
const fixtureTests = (name, f) => {
const fx = loadFixture(name)
fx.cases.forEach((c) =>
test(`m05 ${fx.function}: ${c.name}`, () => assert.deepStrictEqual(f(...freeze(c.args)), c.expected)))
}
fixtureTests('m05-update', update)
fixtureTests('m05-replay', replay)
fixtureTests('m05-history', history)
test('m05 history has one more state than there are actions', () => {
const [state, actions] = loadFixture('m05-replay').cases[0].args
assert.equal(history(freeze(state), freeze(actions)).length, actions.length + 1)
})
test('m05 history starts at the start state and ends where replay ends', () => {
const [state, actions] = freeze(loadFixture('m05-replay').cases[0].args)
const states = history(state, actions)
assert.deepStrictEqual(states[0], state)
assert.deepStrictEqual(states[states.length - 1], replay(state, actions))
})
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import test from 'node:test'
import assert from 'node:assert/strict'
import { CELL, view } from '../src/view.js'
import { loadFixture, freeze } from './helpers.js'
test('m06 CELL is 20 pixels', () => assert.equal(CELL, 20))
const fx = loadFixture('m06-view')
fx.cases.forEach((c) =>
test(`m06 ${fx.function}: ${c.name}`, () => assert.deepStrictEqual(view(...freeze(c.args)), c.expected)))