[BUG] buildPointSeriesData unit test fails due to hard-coded expected value that is not timezone friendly

[evankielley]

Describe the bug
The unit test buildPointSeriesData fails due to trying to match a hard-coded UTC datetime with a datetime generated in accordance with my machine's timezone. A simple fix would be to change the expected values to be moment('2023-01-01') and moment('2023-01-01') instead of '2023-01-01T00:00:00+00:00' and '2023-01-02T00:00:00+00:00'.

To Reproduce
Steps to reproduce the behavior:

1. Run yarn test:jest src/plugins/discover/public/application/components/chart/utils/point_series.test.ts

Expected behavior
The unit test should pass.

OpenSearch Version
N/A

Dashboards Version
N/A

Plugins
N/A

Screenshots

Host/Environment (please complete the following information):

• OS: macOS 13.5.1
• Browser and version: N/A

Additional context
yarn version: 1.22.19
node version: v18.16.0

[ananzh]

@evankielley Thank you for catching this test bug for us and you are absolutely right. I also reproduced and saw the unit test for buildPointSeriesData fails when comparing expected datetime strings. The discrepancy arises from the behavior of the moment library regarding time zones. Specifically, when creating a moment object like moment('2023-01-01'), it uses the local timezone of the machine executing the code. As a result, on a machine set to the -08:00 timezone, the formatted string from the moment object will also carry that -08:00 offset, causing a mismatch with the hard-coded UTC string '2023-01-01T00:00:00+00:00'.

As @evankielley suggested, to ensure consistency across different environments, the date-time strings used within the test should be explicitly defined in UTC. By using a format like moment('2023-01-01T00:00:00Z'), the moment object is set in UTC regardless of the system's local timezone. Thus, when this moment object is formatted, it should consistently produce a UTC timestamp, avoiding discrepancies in different environments.

I will raise a PR to fix it.

[evankielley]

Thanks @ananzh !