add the minimum resource error improvement

[georgeliao]

fixes #2925
This is still a draft implementation, be free to give your comments on it.
The current output error message is like
./multipass launch docker --name load-test --cpus 1 --memory 2G --disk 20GiB

launch failed: Requested Number of CPUs is less than Blueprint minimum of 2
The docker requires at least 2 CPUs, 4G of memory and 40G of disk space.

[codecov]

Codecov Report

Merging #2950 (683b5a3) into main (6ef9ce3) will increase coverage by 0.01%.
The diff coverage is 96.66%.

@@            Coverage Diff             @@
##             main    #2950      +/-   ##
==========================================
+ Coverage   86.89%   86.90%   +0.01%     
==========================================
  Files         231      231              
  Lines       12042    12061      +19     
==========================================
+ Hits        10464    10482      +18     
- Misses       1578     1579       +1     

Impacted Files	Coverage Δ
...nclude/multipass/exceptions/blueprint_exceptions.h	95.00% <95.00%> (-5.00%)	⬇️
...ueprint_provider/default_vm_blueprint_provider.cpp	99.22% <100.00%> (+<0.01%)	⬆️

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[townsend2010]

Hey @georgeliao!

Thanks for this!

I kind of feel that instead of making a call to prepopulate an error message that may or not happen, it may be better to modify BlueprintMinimumException to accept the limits YAML::Node instead and let it be responsible for constructing the error message when needed. I hope this makes sense 🙂

[georgeliao]

@townsend2010
Thanks for your comment. I like what you said "may or not happen". It is something I overlooked. Indeed, the error message generation should happen inside the if and throw blocks. I will refine the code.

[georgeliao]

Hi @townsend2010

The comment is addressed. Please also feel free to comment further if there are still things to improve.

The current output of the program is:
./multipass launch docker --name load-test --cpus 1 --memory 2G --disk 10GiB

launch failed: Requested Number of CPUs is less than Blueprint minimum.
The docker requires at least 2 CPUs, 4G of memory and 40G of disk space.