Test for ~ files, to avoid home deletion

[gaborcsardi]

Closes #120.

[codecov-commenter]

Codecov Report

Merging #156 (1d0870b) into master (8f2a041) will increase coverage by 0.38%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #156      +/-   ##
==========================================
+ Coverage   75.51%   75.89%   +0.38%     
==========================================
  Files          18       18              
  Lines         878      892      +14     
==========================================
+ Hits          663      677      +14     
  Misses        215      215              

Impacted Files	Coverage Δ
R/build.R	100.00% <100.00%> (ø)

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