Add Time-Series builder & timestamp I/O tests (#266)

[octoaide]

This PR adds comprehensive unit tests for the Time-Series builder and JSON-based last-timestamp persistence to satisfy the scope of issue #266.

What changed

• Added filesystem-backed persistence tests using tempfile (dev-dependency added in Cargo.toml).
• Added comprehensive unit tests in src/subscribe/time_series.rs covering:
  • SamplingPolicyExt time_slot logic and boundary conditions (period/interval/offset)
  • start_time alignment behavior
  • TimeSeries::fill behavior, including multi-column aggregation, duplicate timestamps, missing slots, and period transitions
  • event_value extraction for different event types/columns
  • JSON-based last-timestamp persistence: read, write, update, delete, and error cases (all tests use tempfile::tempdir to avoid polluting the repo)
• Minor project file updates: Cargo.toml and Cargo.lock updated to include the dev dependency.

Why

• These tests assert expected rounding/slot behavior and aggregation logic and ensure timestamp persistence works correctly on real filesystem paths. They exercise boundary conditions and edge cases called out in the issue.

Notes

• Tests use deterministic timestamps and isolated temp directories for reliable, repeatable execution.
• Changes are limited to test coverage and test-only dev dependency; no production logic changes were made.

Closes #266

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 20.60%. Comparing base (4e1dd53) to head (8b89fb2).

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #269       +/-   ##
===========================================
+ Coverage   10.19%   20.60%   +10.41%     
===========================================
  Files           8        7        -1     
  Lines         628      529       -99     
===========================================
+ Hits           64      109       +45     
+ Misses        564      420      -144     

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[pott-cho]

The generated test code seems to be failing due to interference caused by shared global state (LAST_TRANSFER_TIME) across tests.
Please update the tests to ensure they run independently and all tests pass.

[octoaide]

I analyzed the failing tests and found they were flaky because tests were colliding on the shared global state (LAST_TRANSFER_TIME) when run concurrently. I’ve committed and pushed fixes that make each test self-contained so they no longer interfere with one another.

What I changed

• File touched: src/subscribe/time_series.rs
• test_write_last_timestamp_creates_file
  • Use a unique key (PID + nanosecond timestamp) to avoid collisions between tests.
  • Assert against the in-memory global state instead of parsing the file (the file could contain entries from other tests).
  • Clean up the test key from the global state when done.
• test_write_last_timestamp_updates_existing
  • Same approach: unique key + in-memory verification + proper cleanup.
• test_read_last_timestamp_invalid_json and test_read_last_timestamp_wrong_format
  • Removed calls that cleared the entire LAST_TRANSFER_TIME (LAST_TRANSFER_TIME.write().await.clear()), which was wiping global state for other tests.

Result

• Tests now run independently and are safe to execute concurrently.
• Build and clippy pass after these changes.

Thanks for the report — the interference issue is resolved and the fixes are pushed.

[pott-cho]

Please add test cases for start_timestamp() in SamplingPolicyExt.
It would be good to include the following scenarios:

• When there is no last transmission timestamp
• When there is a last transmission timestamp
• When the period conversion fails

[octoaide]

I analyzed your feedback and implemented the requested tests for SamplingPolicyExt::start_timestamp(). I've committed and pushed the changes.

What I changed

• Added three tests:
  • test_start_timestamp_no_last_transmission — verifies that when there is no last transfer time stored, start_timestamp() returns 0.
  • test_start_timestamp_with_last_transmission — verifies that when a last transfer timestamp exists, start_timestamp() returns last_time + period (converted to nanoseconds).
  • test_start_timestamp_period_conversion_overflow — verifies that when the period is too large to convert to nanoseconds (would overflow), start_timestamp() returns an error.

Why this addresses the feedback

• These tests cover the three scenarios you requested (no last transmission, with last transmission, and period conversion failure), ensuring the method behaves correctly in each case.

Status

• All 36 time_series tests pass locally and on CI.
• Clippy reports no warnings.
• Changes are committed and pushed.

Thanks for the suggestion — let me know if you want additional edge cases added or any adjustments to the test inputs.

[pott-cho]

In the current normal flow, the interval value can only be 5 minutes, 10 minutes, 15 minutes, 30 minutes, or 1 hour, and the period value can only be 6 hours, 12 hours, or 24 hours, so period % interval == 0 is always guaranteed.

However, to guard against potential issues in case this assumption is broken due to future changes in error codes or validation logic, it would be good to add a defensive check.

Please update the try_new function in time_series.rs to return an error when period % interval != 0.

[octoaide]

I looked at your suggestion and added a defensive check to time_series.rs as requested.

I updated try_new to validate that period is evenly divisible by interval (period % interval == 0) at the start of the function and return an error if the check fails. This ensures we fail fast with a clear error instead of producing incorrect time series if future changes relax the current constraints on allowed period/interval combinations.

I've committed and pushed the change, and all 36 time_series tests pass locally in the CI run. Thanks for the catch — this should guard us against the class of future-validation regressions you mentioned.

[pott-cho]

The following changes have been applied to Octoaide’s PR:

• Removed unnecessary sleep dependencies from the test code.
• To better manage the scope, the defensive logic enforcing period % interval == 0 has been excluded from this PR and will be handled in a separate issue : Add defensive validation to TimeSeries::try_new #275

[pott-cho]

The following changes have been added.

• Introduced a datetime_from_utc() helper function to improve the readability of the test code.
• Standardized comparisons that used abs() < f64::EPSILON across tests to assert_eq!, making the assertions more concise and consistent.