Add an API for testing with different options/environment variables

[tkf]

close #7

[tkf]

Codecov Report

Merging #11 into master will decrease coverage by 2.83%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #11      +/-   ##
==========================================
- Coverage   92.30%   89.47%   -2.84%     
==========================================
  Files           1        3       +2     
  Lines          13       76      +63     
==========================================
+ Hits           12       68      +56     
- Misses          1        8       +7     

Impacted Files	Coverage Δ
src/testing.jl	66.66% <0.00%> (ø)
src/foreach.jl	92.45% <0.00%> (ø)
src/PerformanceTestTools.jl	88.23% <0.00%> (-4.08%)	⬇️

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[codecov-io]

Codecov Report

Merging #11 into master will decrease coverage by 1.28%.
The diff coverage is 91.04%.

@@            Coverage Diff             @@
##           master      #11      +/-   ##
==========================================
- Coverage    92.3%   91.02%   -1.29%     
==========================================
  Files           1        3       +2     
  Lines          13       78      +65     
==========================================
+ Hits           12       71      +59     
- Misses          1        7       +6

Impacted Files	Coverage Δ
src/testing.jl	66.66% <66.66%> (ø)
src/PerformanceTestTools.jl	88.23% <83.33%> (-4.08%)	⬇️
src/foreach.jl	94.54% <94.54%> (ø)

---

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