feat: creating new mx_ suite of macros!

also adding new mx_getcode macro

tests/base/mp_dirlist.test.sas

@@ -0,0 +1,65 @@
+/**
+  @file
+  @brief Testing mp_dirlist.sas macro
+
+  <h4> SAS Macros </h4>
+  @li mf_nobs.sas
+  @li mf_mkdir.sas
+  @li mp_dirlist.sas
+  @li mp_assert.sas
+
+**/
+
+/**
+  * make a directory structure
+  */
+
+%let root=%sysfunc(pathname(work))/top;
+%mf_mkdir(&root)
+%mf_mkdir(&root/a)
+%mf_mkdir(&root/b)
+%mf_mkdir(&root/a/d)
+%mf_mkdir(&root/a/e)
+%mf_mkdir(&root/a/e/f)
+libname test "&root/a/e/f";
+data test.ds1;
+  x=1;
+run;
+
+%mp_dirlist(path=&root, outds=myTable, maxdepth=MAX)
+
+%mp_assert(
+  iftrue=(%mf_nobs(work.mytable)=6),
+  desc=All levels returned,
+  outds=work.test_results
+)
+
+%mp_dirlist(path=&root, outds=myTable2, maxdepth=2)
+
+%mp_assert(
+  iftrue=(%mf_nobs(work.mytable2)=5),
+  desc=Top two levels returned,
+  outds=work.test_results
+)
+
+%mp_dirlist(path=&root, outds=work.myTable3, maxdepth=0)
+
+%mp_assert(
+  iftrue=(%mf_nobs(work.mytable3)=2),
+  desc=Top level returned,
+  outds=work.test_results
+)
+
+%mp_dirlist(path=&root/b, outds=work.myTable4)
+%mp_assert(
+  iftrue=(%mf_nobs(work.mytable4)=0),
+  desc=Empty table for empty directory,
+  outds=work.test_results
+)
+
+%mp_dirlist(path=&root/notexisting, outds=work.myTable5)
+%mp_assert(
+  iftrue=(%mf_nobs(work.mytable5)=0),
+  desc=Empty table for non-existing directory,
+  outds=work.test_results
+)