tests: Add tests for go/vt/external

[Maniktherana]

Description

Bumps coverage from 15.4% to 61.5%

Question: some functions require a db *sql.DB as an argument. Not sure how to approach testing these. Do I make a sqlite DB to test them or use sqlmock?

Related Issue(s)

#14931

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1bf8dda) 47.36% compared to head (1b44df1) 47.39%.
Report is 6 commits behind head on main.

❗ Current head 1b44df1 differs from pull request most recent head c5d9bda. Consider uploading reports for the commit c5d9bda to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15023      +/-   ##
==========================================
+ Coverage   47.36%   47.39%   +0.02%     
==========================================
  Files        1144     1144              
  Lines      238995   238995              
==========================================
+ Hits       113197   113267      +70     
+ Misses     117213   117137      -76     
- Partials     8585     8591       +6     

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[frouioui]

some functions require a db *sql.DB as an argument. Not sure how to approach testing these. Do I make a sqlite DB to test them or use sqlmock?

We usually have E2E tests for these, perhaps we already have for these functions/features actually. But coverage is not enabled yet for E2E tests (#14932)

[frouioui]

Besides the comments I left it looks good to me.

[GuptaManan100]

LGTM!