Step 7: Tests

[thanos]

Step 7: Tests

Create test/ex_data_sketch_ull_test.exs

• Construction tests: default p, custom p, binary size 8 + 2^p, header fields, validation
• Backend-parameterized tests: update, update_many, estimate accuracy (assert_in_delta 5% at p=14)
• Merge tests: commutativity (state ==), identity, incompatible p raises
• Serialize/deserialize round-trip
• Property tests: merge commutativity, merge associativity, monotonicity, serialize round-trip
• Cross-backend parity block (guarded by Backend.Rust.available?())

Modify test/parity_test.exs

• Add describe "ULL parity" block with @describetag :rust_nif
• Tests: update_many byte-identical serialization, merge byte-identical, estimate within 1.0e-9

Modify test/merge_laws_test.exs

• Add ULL merge laws: commutativity (state==), associativity (state==), identity, chunking equivalence (1% delta)

Create test/vectors/ull/ directory with 4 JSON vectors:

• empty.json, single.json, small_set.json, merge.json

Modify test/support/test_vectors.ex

• Add normalize_opts("ull", ...) clause
• Add sketch_module("ull") clause

Modify test/json_vector_test.exs

• Add "ull" to the algo iteration list