Add test for discord and refactor

[KeisukeYamashita]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

Any specific area of the project related to this PR?

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/area build

/area config

/area outputs

/area tests

/area helm

What this PR does / why we need it:

I want to refactor and add tests for it.
With the test, I was able to refactor safely.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

[poiana]

@KeisukeYamashita: The label(s) area/build cannot be applied, because the repository doesn't have them

In response to this:

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area build

/area config

/area outputs

/area tests

/area helm

What this PR does / why we need it:

I want to refactor and add tests for it.
With the test, I was able to refactor safely.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

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.

[poiana]

LGTM label has been added.

Git tree hash: 194cbf13a8375e9ec54453353a61289514a7e997

[poiana]

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