Add test for precision conversion with decl_hdf5

[Yushan-Wang]

List of things to check before making a PR

Before merging your code, please check the following:

• you have added a line describing your changes to the Changelog;
• you have added unit tests for any new or improved feature;
• in case you updated dependencies, you have checked pdi/docs/CheckList.md;
• in case of a change in pdi.h, this same change must be reflected in no-pdi/include/pdi.h;
• you have checked your code format:
  • you have checked that you respect all conventions specified in CONTRIBUTING.md;
  • you have checked that the indentation and formatting conforms to the .clang-format;
  • you have documented with doxygen any new or changed function / class;
• you have correctly updated the copyright headers:
  • your institution is in the copyright header of every file you (substantially) modified;
  • you have checked that the end-year of the copyright there is the current one;
• you have updated the AUTHORS file:
  • you have added yourself to the AUTHORS file;
  • if this is a new contribution, you have added it to the AUTHORS file;
• you have added everything to the user documentation:
  • any new CMake configuration option;
  • any change in the yaml config;
  • any change to the public or plugin API;
  • any other new or changed user-facing feature;
  • any change to the dependencies;
• you have correctly linked your MR to one or more issues:
  • your MR solves an identified issue;
  • your commit contain the Fix #issue keyword to autoclose the issue when merged.

[jbigot]

Do you feel it would be a good candidate to demonstrate the use of #669 ?

[jmorice91]

look goods for me.
If your input double data is 1.5d0=1.50...0, how to know that the convention between HDF5 and gtest for transformation of double to int is the same?

Have you tested that?

As we use random number, it is a rare event that is arrived.

[Yushan-Wang]

look goods for me. If your input double data is 1.5d0=1.50...0, how to know that the convention between HDF5 and gtest for transformation of double to int is the same?

Have you tested that?

As we use random number, it is a rare event that is arrived.

HDF5 truncates floating-point numbers to integers upon precision conversion. So 1.5 would be output as 1. Same for static_cast