Tests: improve coverage of Network

[erlend-aasland]

I'm not sure if I'm satisfied with this yet; I'll have another look tomorrow before marking it as ready for review.

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 70.17%. Comparing base (a196e1e) to head (d8d8d3c).

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Additional details and impacted files

[](https://app.codecov.io/gh/christiansandberg/canopen/pull/515?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Christian+Sandberg) ```diff @@ Coverage Diff @@ ## master #515 +/- ## ========================================== + Coverage 68.86% 70.17% +1.31% ========================================== Files 26 26 Lines 3112 3112 Branches 526 526 ========================================== + Hits 2143 2184 +41 + Misses 831 800 -31 + Partials 138 128 -10 ``` [see 5 files with indirect coverage changes](https://app.codecov.io/gh/christiansandberg/canopen/pull/515/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Christian+Sandberg)

[erlend-aasland]

Thank you for the review!