49 add testcase for data retrieve

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 35.16%. Comparing base (90d48ff) to head (cc8fdf3).

Files	Patch %	Lines
kenmerkendewaarden/data_retrieve.py	33.33%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #50 +/- ## =========================================== + Coverage 18.07% 35.16% +17.09% =========================================== Files 8 8 Lines 902 890 -12 =========================================== + Hits 163 313 +150 + Misses 739 577 -162 ```

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[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud