Synthetic data generation for property-based testing of the TS api

[tslil-topos]

In #1349 we added a script to dump documents from a running instance of CatColab on AWS infra. The data is in some sense incidental to the goals of the change: ensure that semantic-preserving changes are reservable and preserve document validity.

The proposal is to leverage the typescript api itself, or failing that, the lower-level document methods to randomly generate valid notebooks as the data source for these tests.

This will allow us to avoid:

• gating running these tests on AWS access
• committing a blob snapshot of the data source to the repo
• potential desync between the nature of the data and the current changes to the API

There appear to be medium-low effort ways to do this (eg: randomly picking a shape, if it requires references to other cells pick among the generated one or make news, etc) and this should be investigated before we make concrete decisions about wiring these tests into the CI.

[kasbah]

For reference, existing property test that generates model notebooks:

CatColab/packages/document-types/src/automerge_json.rs

Lines 412 to 418 in a2b457a

	/// A `ModelNotebook` survives a JSON → Automerge → JSON roundtrip.
	#[proptest(cases = 64)]
	fn model_notebook_roundtrips_through_automerge(notebook: ModelNotebook) {
	let json = serde_json::to_value(&notebook.0).expect("serialize to JSON");
	let result = roundtrip_json(&json);
	proptest::prop_assert_eq!(json, result);
	}

document-types has no concept of a valid model notebook of a particular logic of course, and the generators are very simplistic and will generate non-sensical notebooks.

CatColab/packages/document-types/src/v1/notebook.rs

Lines 38 to 62 in bec65a6

	pub fn arb_notebook<T: std::fmt::Debug + 'static>(
	arb_t: impl Strategy<Value = T> + Clone + 'static,
	) -> BoxedStrategy<Notebook<T>> {
	prop::collection::vec((arb_uuid(), arb_notebook_cell(arb_t)), 0..6)
	.prop_map(|entries| {
	let mut cell_contents = HashMap::new();
	let mut cell_order = Vec::new();
	for (id, cell) in entries {
	// Replace the cell's internal id with the map key for
	// consistency, matching how real notebooks work.
	let cell = match cell {
	NotebookCell::RichText { content, .. } => {
	NotebookCell::RichText { id, content }
	}
	NotebookCell::Formal { content, .. } => {
	NotebookCell::Formal { id, content }
	}
	NotebookCell::Stem { .. } => NotebookCell::Stem { id },
	};
	cell_contents.insert(id, cell);
	cell_order.push(id);
	}
	Notebook { cell_contents, cell_order }
	})
	.boxed()