The DYNAMIC_ARRAY type ( defined in my_sys.h with code in mysys/array.c ) is still used in hundreds of places in the code, especially in C code which obviously does not have easy access to standard C++ classes.

However, the testing of this code is indirect testing of DYNAMIC_ARRAY as integrated in the other code.

By contrast, the DYNAMIC_STRING has unittest/mysys/dynstring-t.c which shows basic usage and tests for basic correctness.

The absence of a similar test for DYNAMIC_ARRAY seems like an oversight.