feat: adding mfv_existfile.sas and tests

tests/viya/mfv_existfile.test.sas

@@ -0,0 +1,34 @@
+/**
+  @file
+  @brief Testing mfv_existfile macro function
+
+  <h4> SAS Macros </h4>
+  @li mf_uid.sas
+  @li mfv_existfile.sas
+  @li mp_assert.sas
+  @li mv_createfile.sas
+
+**/
+
+options mprint sgen;
+
+%let file=%mf_uid();
+
+/* create a folder */
+filename somefile temp;
+data _null_;
+  file somefile;
+  put 'hello testings';
+run;
+%mv_createfile(path=&mcTestAppLoc/temp, name=&file..txt,inref=somefile)
+
+
+%mp_assert(
+  iftrue=(%mfv_existfile(&mcTestAppLoc/temp/&file..txt)=1),
+  desc=Check if created file exists
+)
+
+%mp_assert(
+  iftrue=(%mfv_existfile(&mcTestAppLoc/temp/%mf_uid().txt)=0),
+  desc=Check if non created file does not exist
+)

viya/mfv_existfile.sas

@@ -0,0 +1,48 @@
+/**
+  @file
+  @brief Checks whether a file exists in SAS Drive
+  @details Returns 1 if the file exists, and 0 if it doesn't.  Works by
+  attempting to assign a fileref with the filesrvc engine.  If not found, the
+  syscc is automatically set to a non zero value - so in this case it is reset.
+  To avoid hiding issues, there is therefore a test at the start to ensure the
+  syscc is zero.
+
+  Usage:
+
+    %put %mfv_existfile(/does/exist.txt);
+    %put %mfv_existfile(/does/not/exist.txt);
+
+  @param filepath The full path to the file on SAS drive (eg /Public/myfile.txt)
+
+  <h4> SAS Macros </h4>
+  @li mf_abort.sas
+  @li mf_getuniquefileref.sas
+
+  @version 3.5
+  @author [Allan Bowe](https://www.linkedin.com/in/allanbowe/)
+**/
+
+%macro mfv_existfile(filepath
+)/*/STORE SOURCE*/;
+
+  %mf_abort(
+    iftrue=(&syscc ne 0),
+    msg=Cannot enter mfv_existfile.sas with syscc=&syscc
+  )
+
+  %local fref rc path name;
+  %let fref=%mf_getuniquefileref();
+  %let name=%scan(&filepath,-1,/);
+  %let path=%substr(&filepath,1,%length(&filepath)-%length(&name)-1);
+
+  %if %sysfunc(filename(fref,,filesrvc,folderPath="&path" filename="&name"))=0
+  %then %do;
+    %sysfunc(fexist(&fref))
+    %let rc=%sysfunc(filename(fref));
+  %end;
+  %else %do;
+    0
+    %let syscc=0;
+  %end;
+
+%mend mfv_existfile;