NOTE: Macros Newness in 9.4 and 9.3 (MCOVERAGE)

The SAS macro language is almost as old as SAS itself (who knows exactly?) so you'd think the need to add new functionality would have ceased - particularly with the ability to access most DATA step functions through %sysexec. But apparently not...

SAS V9.4 introduces a few new macro features, but not a huge number. The two that caught my eye were:

1. The SYSDATASTEPPHASE automatic macro variable which offers an insight into the current running phase of the DATA step
2. The READONLY option on %local and %global.

Not so long ago, SAS V9.3 introduced a raft of new automatic macro variables, macro functions, macro statements and macro system options.

When 9.3 was launched, one of the new system options caught my eye: MCOVERAGE. It claimed to offer coverage analysis for macros, i.e. highlighting which macro code lines were executed and which were not (particularly useful whilst testing your macros). When I wrote of the release of 9.3 I didn't have immediate access to 9.3, the documentation offered little in the way of real-world explanation, and (I confess) I forgot to return to the topic when I got use of a copy of 9.3.

Well, I was reminded of MCOVERAGE recently and I've spent a bit of time over Christmas figuring out how it works and what it offers in real terms (what is Christmas for if it's not for indulging yourself in things you love?). If you do a lot of macro coding then you'll be interested to know that MCOVERAGE offers plenty. Read on...

Consider this piece of code:

filename MClog "~/mcoverage1.log";

options mcoverage mcoverageloc=MClog;

%fred(param=2);

filename MClog clear;

The SAS log doesn't include any extra information, but we've created a new file named mcoverage1.log in our unix home directory (if you're on Windows, substitute "~/mcoverage1.log" with "C:\mcoverage1.log". I'll describe what the %fred macro does later but, for now, let's just say it's a macro that we want to test. So, we've tested it (with param=2), it worked fine, but have we tested all of the lines of code, or did we only execute a sub-set of the whole macro? If we look into mcoverage1.log we can find the answer. It looks like this:

1 1 18 FRED
2 1 1 FRED
3 17 17 FRED
2 1 1 FRED
2 2 2 FRED
2 3 3 FRED
2 4 4 FRED
2 4 4 FRED
2 4 4 FRED
2 5 5 FRED
2 6 6 FRED
2 7 7 FRED
2 8 8 FRED
2 8 8 FRED
2 9 9 FRED
2 13 13 FRED
2 18 18 FRED

What does this mean? I'll explain tomorrow...

But before tomorrow, I must add one further piece of information. In order to see the mcoverage log, it needs to be closed by SAS. One does this by coding filename MClog clear;. However, I found that SAS refused to close the file because it was "in use". Even coding options nomcoverage; before closing it didn't help. In the end I resorted to running another (null) macro after setting nomcoverage. This did the trick, but if anybody can suggest how I can more easily free-up the mcoverage log I'd be very interested to hear. Here's the full code that I used:

%macro null;%mend null;

filename MClog "~/mcoverage1.log";

options mcoverage mcoverageloc=MClog;

%include "~/fred.sas";

%fred(param=2);

options nomcoverage mcoverageloc='.';

%null;

filename MClog clear;

MCOVERAGE:

NOTE: Macros Newness in 9.4 and 9.3 (MCOVERAGE), 6-Jan-2014 (this article!)
NOTE: Macro Coverage in Testing (MCOVERAGE), 7-Jan-2014
NOTE: Making Sense of MCOVERAGE for Coverage Testing of Your Macros, 8-Jan-2014
NOTE: Expanding Our Use of MCOVERAGE for Coverage Analysis of our Macro Testing, 9-Jan-2014
NOTE: Wrap-Up on Test Coverage and MCOVERAGE, 10-Jan-2014