add unit tests for yurthub data filtering framework

[windydayc]

What type of PR is this?

/kind good-first-issue
/kind feature

What this PR does / why we need it:

Data filtering framework is an elegant feature of yurthub, but it lacks unit tests.

Which issue(s) this PR fixes:

Fixes #418

Special notes for your reviewer:

/assign @rambohe-ch

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In response to this:

What type of PR is this?

/kind good-first-issue
/kind feature

What this PR does / why we need it:

Data filtering framework is elegant feature of yurthub, but it lacks unit tests.

Which issue(s) this PR fixes:

Fixes #418

Special notes for your reviewer:

/assign @rambohe-ch

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[rambohe-ch]

@windydayc Very appreciate for adding test case for data filter framework of yurthub, it's a good job.

[rambohe-ch]

/lgtm
/approve

[openyurt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rambohe-ch, windydayc

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