Update result analyzer and remaining changes

[eerxuan]

Update result_analyzer with improved categorization and reporting.

This has dependency on #20.

Demo of the report output:

Before the PR in console:

============================================================
Test Results Summary
============================================================
Total:   44
Passed:  39 (88.64%)
Failed:  4
Skipped: 1
============================================================

Before the PR in output file:

================================================================================
DocumentDB Functional Test Results
================================================================================
Generated: 2026-04-02 23:36:18 UTC

SUMMARY
--------------------------------------------------------------------------------
Total Tests:  44
Passed:       39 (88.64%)
Failed:       4
Skipped:      1

RESULTS BY TAG
--------------------------------------------------------------------------------
No tags found in test results.

FAILED TESTS
--------------------------------------------------------------------------------

documentdb_tests/compatibility/tests/core/query-and-write/commands/find/test_find_basic_queries.py::test_fake_mismatch
  Tags:
  Duration: 0.00s
  Error: AssertionError: [RESULT_MISMATCH] Expected [1,2,3] but got [1,2]...

documentdb_tests/compatibility/tests/core/operator/stages/group/test_group_stage.py::test_fake_connection_error
  Tags:
  Duration: 0.00s
  Error: ConnectionError: Cannot connect to mongodb at localhost:27017...

documentdb_tests/compatibility/tests/core/query-and-write/commands/insert/test_insert_operations.py::test_fake_unexpected
  Tags:
  Duration: 0.00s
  Error: AssertionError: [UNEXPECTED_ERROR] Expected success but got exception...

documentdb_tests/compatibility/tests/core/query-and-write/commands/find/test_find_basic_queries.py::test_fake_error_mismatch
  Tags:
  Duration: 0.00s
  Error: AssertionError: [ERROR_MISMATCH] Expected code 11000 but got 26...

================================================================================

After the PR in console:

============================================================
Test Results Summary
============================================================
Total:   44
Passed:  39 (88.64%)
Failed:  4
Skipped: 1
============================================================

Failed Tests (4):
------------------------------------------------------------
  ERROR_MISMATCH: 1
  INFRA_ERROR: 1
  RESULT_MISMATCH: 1
  UNEXPECTED_ERROR: 1
============================================================

After the PR in output file:

================================================================================
DocumentDB Functional Test Results
================================================================================
Generated: 2026-04-02 23:48:20 UTC

SUMMARY
--------------------------------------------------------------------------------
Total Tests:  44
Passed:       39 (88.64%)
Failed:       4
Skipped:      1

RESULTS BY TAG
--------------------------------------------------------------------------------

aggregate:
  Total:   11
  Passed:  9 (81.82%)
  Failed:  1
  Skipped: 1

smoke:
  Total:   7
  Passed:  6 (85.71%)
  Failed:  1
  Skipped: 0

insert:
  Total:   8
  Passed:  7 (87.5%)
  Failed:  1
  Skipped: 0

find:
  Total:   24
  Passed:  22 (91.67%)
  Failed:  2
  Skipped: 0

collection_mgmt:
  Total:   1
  Passed:  1 (100.0%)
  Failed:  0
  Skipped: 0

FAILED TESTS
--------------------------------------------------------------------------------

  ERROR_MISMATCH (1):

    documentdb_tests/compatibility/tests/core/query-and-write/commands/find/test_find_basic_queries.py::test_fake_error_mismatch
      Tags: find
      Duration: 0.00s
      Error: AssertionError: [ERROR_MISMATCH] Expected code 11000 but got 26...

  INFRA_ERROR (1):

    documentdb_tests/compatibility/tests/core/operator/stages/group/test_group_stage.py::test_fake_connection_error
      Tags: aggregate
      Duration: 0.00s
      Error: ConnectionError: Cannot connect to mongodb at localhost:27017...

  RESULT_MISMATCH (1):

    documentdb_tests/compatibility/tests/core/query-and-write/commands/find/test_find_basic_queries.py::test_fake_mismatch
      Tags: find, smoke
      Duration: 0.00s
      Error: AssertionError: [RESULT_MISMATCH] Expected [1,2,3] but got [1,2]...

  UNEXPECTED_ERROR (1):

    documentdb_tests/compatibility/tests/core/query-and-write/commands/insert/test_insert_operations.py::test_fake_unexpected
      Tags: insert
      Duration: 0.00s
      Error: AssertionError: [UNEXPECTED_ERROR] Expected success but got exception...

SKIPPED TESTS
--------------------------------------------------------------------------------
  documentdb_tests/compatibility/tests/core/operator/stages/match/test_match_stage.py::test_fake_skipped

================================================================================

[xgerman]

LGTM as a human.

AI felt this could be done:
Issues Found

🟡 Medium — Import at function scope inside print_summary() report_generator.py line ~158: from collections
import Counter is imported inside the function body. This should be a top-level import per PEP 8. It works, but
is inconsistent with the rest of the file.

🟡 Medium — failure_type not set for non-FAIL outcomes analyzer.py line ~340-345: failure_type is only added to
the test detail dict when test_outcome == FAIL. But report_generator.py calls test.get("failure_type", "UNKNOWN")
— this works due to .get() with default, but the field's conditional presence is fragile. Consider always setting
it (e.g., "N/A" for passed/skipped).

🟢 Minor — Trailing whitespace cleanup is noise Many hunks are whitespace-only changes (trailing spaces removed).
Not a problem, but inflates the diff. Could have been a separate commit.

🟢 Minor — extract_failure_tag regex is broad

match = re.search(r'[([A-Z_]+)]', crash_message)

This matches any [UPPER_CASE] bracket pattern. If a crash message happens to contain something like
[SOME_BSON_KEY], it could false-match. Not likely in practice but worth noting.

🟢 Minor — Empty init.py tests/collection/init.py is added with just a docstring. Fine for package
recognition, but if PR #20 already added test files under tests/collection/, this should have been part of that
PR.