Improve code coverage in test

[codecov[bot]]

Codecov Report

Merging #45 (ac197fe) into main (df62ef8) will increase coverage by 3.54%. The diff coverage is 95.83%.

:exclamation: Current head ac197fe differs from pull request most recent head 421e94c. Consider uploading reports for the commit 421e94c to get more accurate results

@@            Coverage Diff             @@
##             main      #45      +/-   ##
==========================================
+ Coverage   89.51%   93.05%   +3.54%     
==========================================
  Files          17       17              
  Lines        6302     6293       -9     
==========================================
+ Hits         5641     5856     +215     
+ Misses        661      437     -224     

Impacted Files	Coverage Δ
pygmtools/linear_solvers.py	84.21% <0.00%> (+5.26%)	:arrow_up:
pygmtools/paddle_backend.py	94.80% <ø> (+0.93%)	:arrow_up:
pygmtools/benchmark.py	97.28% <100.00%> (+9.00%)	:arrow_up:
pygmtools/dataset.py	90.83% <100.00%> (+15.75%)	:arrow_up:
pygmtools/dataset_config.py	100.00% <100.00%> (ø)
pygmtools/neural_solvers.py	89.05% <100.00%> (+1.14%)	:arrow_up:
pygmtools/numpy_backend.py	95.52% <100.00%> (+0.88%)	:arrow_up:
pygmtools/tensorflow_backend.py	94.53% <0.00%> (-0.02%)	:arrow_down:
pygmtools/utils.py	84.13% <0.00%> (ø)
... and 6 more

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