[coverage] Conformance findings: COMPLEX-015,COMPLEX-016

[peco-engineer-bot]

Summary

Surfaced by the multi-language coverage fan-out while conformance-testing these SPEC-IDs against databricks/databricks-sql-python. Each finding is committed as an expected-failure (xfail) test in the coverage PR — the test asserts the CORRECT (post-fix) behavior and stays red until THIS driver (databricks/databricks-sql-python) is fixed, then flips green as a tripwire.

Findings

• COMPLEX-015 [sea]: Kernel/SEA renders nested DOUBLE leaves with a shortest-decimal JSON writer (0.0001, 100, 1e21 expanded to plain digits) instead of the canonical forced-fraction, capital-'E', unsigned-unpadded-exponent layout
  • failing test: test_nested_double_leaf_text_spelling (see the coverage PR diff under tests/)
• COMPLEX-016 [sea]: Kernel/SEA renders a nested TIMESTAMP leaf as an ISO-8601 UTC instant with a fixed 6-digit fraction and a 'Z' ("2025-01-24T07:07:41.000000Z") instead of the session-timezone wall clock its top-level TIMESTAMP->text path emits
  • failing test: test_nested_timestamp_leaf_text_spelling (see the coverage PR diff under tests/)
• COMPLEX-015: Kernel/SEA backend renders nested DOUBLE leaves in a complex column's JSON text surface with a shortest-decimal writer (0.0001, 100, 1e21 expanded to plain digits) instead of the canonical forced-fraction, capital-'E', unsigned-unpadded-exponent layout the Thrift path and reference drivers emit
• COMPLEX-016: Kernel/SEA backend renders a nested TIMESTAMP leaf as an ISO-8601 UTC instant with a fixed 6-digit fraction and a 'Z' suffix ("2025-01-24T07:07:41.000000Z") instead of the session-timezone wall clock with trailing-zero fractions stripped that the same instant gets as a top-level TIMESTAMP read as text

Reproduce & Expected

COMPLEX-015 — Verify that a DOUBLE nested inside a complex type (STRUCT / ARRAY / MAP) and read through the driver's TEXT surface is spelled with the canonical layout: a forced fractional part, capital-'E' scienti…

Expected (per the shared spec):

• result has exactly 1 row(s)
• result has 3 column(s)
• full assertion contract:

result:
- row_count: 1
- column_count: 3
- nested_leaf_text_spelling:
    column: struct_doubles
    leaves:
      sci: 3.2033798725730455E8
      small: '1.0E-4'
      whole: '100.0'
      big: 1.0E21
      tiny: '1.0E-7'
- nested_leaf_text_spelling:
    column: array_doubles
    leaves:
    - '1.0'
    - '-2.5'
    - 1.0E7
    - '9999999.0'
    - '0.001'
    - 1.0E100
- nested_leaf_text_spelling:
    column: map_double
    leaves:
      d: '1.0E-4'

COMPLEX-016 — Verify that a TIMESTAMP nested inside a complex type (STRUCT / ARRAY / MAP) and read through the driver's TEXT surface is spelled as the session-timezone wall clock with trailing-zero fractional seco…

Expected (per the shared spec):

• result has exactly 1 row(s)
• result has 3 column(s)
• full assertion contract:

result:
- row_count: 1
- column_count: 3
- nested_leaf_text_spelling:
    column: struct_ts
    leaves:
      ts: '2025-01-24 07:07:41'
- nested_leaf_text_spelling:
    column: array_ts
    leaves:
    - '2024-01-15 12:30:45.123456'
- nested_leaf_text_spelling:
    column: map_ts
    leaves:
      k: '2025-01-24 07:07:41'

Context

• The behavior was first fixed in a DIFFERENT driver — reference PR: https://github.com/databricks/databricks-odbc/pull/215 — which seeded the shared language-neutral spec. This issue tracks the same conformance gap in databricks/databricks-sql-python; the reference PR is for cross-referencing the intended behavior, NOT a change to this repo.
• Coverage PR carrying the reproducing xfail test(s): https://github.com/databricks/databricks-driver-test/pull/1170