Collection Strategy¶

Controls the size range of generated collections during fixture generation.

Configuration¶

The CollectionStrategy takes a single sizeRange parameter — an IntRange specifying the minimum and maximum number of elements in generated collections.

// Default: 1 to 5 elements
some { collectionStrategy = CollectionStrategy() }

// Small collections: 0 to 2 elements
some { collectionStrategy = CollectionStrategy(0..2) }

// Medium collections: 10 to 20 elements
some { collectionStrategy = CollectionStrategy(10..20) }

// Large collections: 50 to 100 elements
some { collectionStrategy = CollectionStrategy(50..100) }

// Fixed size: always exactly 3 elements
some { collectionStrategy = CollectionStrategy(3..3) }

Default¶

Affected types¶

The collection strategy applies to all collection and array types generated by Some:

• List<T>
• MutableList<T>
• Set<T>
• MutableSet<T>
• Map<K, V>
• MutableMap<K, V>
• Array<T>

Validation¶

The CollectionStrategy constructor enforces two constraints on the sizeRange parameter via require() checks. Both throw IllegalArgumentException on failure.

Start must be non-negative¶

sizeRange.first (the start of the range) must be > -1, meaning it must be 0 or greater.

CollectionStrategy(-1..5)  // IllegalArgumentException: sizeRange.start must be positive
CollectionStrategy(0..5)   // OK — empty collections are allowed
CollectionStrategy(1..5)   // OK

End must be strictly greater than start¶

sizeRange.last (the end of the range) must be strictly greater than sizeRange.first. This means a range with equal bounds (e.g. 3..3) is not valid — there must be at least one possible size.

CollectionStrategy(5..3)  // IllegalArgumentException: sizeRange.end must be greater than or equal to sizeRange.start
CollectionStrategy(3..3)  // IllegalArgumentException: end is not greater than start
CollectionStrategy(3..4)  // OK — produces collections of size 3 or 4

Note that the error message says "greater than or equal to" but the actual check is strict (last > first). Equal bounds are rejected.