Add tests for xmagics

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[codecov-commenter]

Codecov Report

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

Project coverage is 79.31%. Comparing base (f4b9593) to head (ca7401d). Report is 1 commits behind head on main.

Additional details and impacted files

[](https://app.codecov.io/gh/compiler-research/xeus-cpp/pull/138?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=compiler-research) ```diff @@ Coverage Diff @@ ## main #138 +/- ## ========================================== + Coverage 75.08% 79.31% +4.22% ========================================== Files 17 17 Lines 602 609 +7 Branches 59 59 ========================================== + Hits 452 483 +31 + Misses 150 126 -24 ``` [see 2 files with indirect coverage changes](https://app.codecov.io/gh/compiler-research/xeus-cpp/pull/138/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=compiler-research) [see 2 files with indirect coverage changes](https://app.codecov.io/gh/compiler-research/xeus-cpp/pull/138/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=compiler-research)

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"