Function arb_relation_desc_diff

src/repr/src/relation.rs:2014–2097

(
    source: &RelationDesc,
)

/// Generates a set of [`PropRelationDescDiff`]s based on some source [`RelationDesc`].
#[cfg(any(test, feature = "proptest"))]
pub fn arb_relation_desc_diff(
    source: &RelationDesc,
) -> impl Strategy<Value = Vec<PropRelationDescDiff>> + use<> {
    let source = Rc::new(source.clone());
    let num_source_columns = source.typ.columns().len();

    let num_add_columns = Union::new_weighted(vec![(100, Just(0..8)), (1, Just(8..64))]);
    let add_columns_strat = num_add_columns
        .prop_flat_map(|num_columns| {
            proptest::collection::vec((any::<ColumnName>(), any::<SqlColumnType>()), num_columns)
        })
        .prop_map(|cols| {
            cols.into_iter()
                .map(|(name, typ)| PropRelationDescDiff::AddColumn { name, typ })
                .collect::<Vec<_>>()
        });

    // If the source RelationDesc is empty there is nothing else to do.
    if num_source_columns == 0 {
        return add_columns_strat.boxed();
    }

    let source_ = Rc::clone(&source);
    let drop_columns_strat = (0..num_source_columns).prop_perturb(move |num_columns, mut rng| {
        let mut set = BTreeSet::default();
        for _ in 0..num_columns {
            let col_idx = rng.random_range(0..num_source_columns);
            set.insert(source_.get_name(col_idx).clone());
        }
        set.into_iter()
            .map(|name| PropRelationDescDiff::DropColumn { name })
            .collect::<Vec<_>>()
    });

    let source_ = Rc::clone(&source);
    let toggle_nullability_strat =
        (0..num_source_columns).prop_perturb(move |num_columns, mut rng| {
            let mut set = BTreeSet::default();
            for _ in 0..num_columns {
                let col_idx = rng.random_range(0..num_source_columns);
                set.insert(source_.get_name(col_idx).clone());
            }
            set.into_iter()
                .map(|name| PropRelationDescDiff::ToggleNullability { name })
                .collect::<Vec<_>>()
        });

    let source_ = Rc::clone(&source);
    let change_type_strat = (0..num_source_columns)
        .prop_perturb(move |num_columns, mut rng| {
            let mut set = BTreeSet::default();
            for _ in 0..num_columns {
                let col_idx = rng.random_range(0..num_source_columns);
                set.insert(source_.get_name(col_idx).clone());
            }
            set
        })
        .prop_flat_map(|cols| {