Tuesday 7 January 2014

NOTE: Macro Coverage in Testing (MCOVERAGE)

Yesterday I introduced the MCOVERAGE system option (introduced in V9.3) for capturing coverage of macro execution. This is useful in testing, to be sure you executed all lines of your macro. This may take more than one execution of your macro, with different input parameters and data.

I finished yesterday's post by showing the mcoverage log file created from the execution of a sample macro. I've listed all three files below. They are:
  1. The program that I ran
  2. The mcoverage log file
  3. The macro source for %fred (with line numbers added; the blank lines were intentional, to show how they are dealt with by MCOVERAGE)

filename MClog "~/mcoverage1.log";

options mcoverage mcoverageloc=MClog;


filename MClog clear;

* BUT, see my note about closing MClog at
  the end of yesterday's blog post;

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

2.  %macro fred(param=2);
3.    * comment ;
4.    %put hello world: ¶m;
5.    %if 1 eq 1 %then %put TRUE;
6.    %if 1 eq 1 %then 
7.    %do;
8.      %put SO TRUE;
9.    %end;
10.   %if 1 eq 0 %then 
11.   %do;
12.     %put FALSE;
13.   %end;
14.   %if &param eq 1 %then
15.   %do;
16.     %put FOUND ME;
17.   %end;
19. %mend fred;

The SAS 9.4 Macro Language: Reference manual tells us that the format of the coverage analysis data is a space delimited flat text file that contains three types of records. Field one of the log file contains the record type indicator. The record type indicator can be:
  • 1 = indicates the beginning of the execution of a macro. Record type 1 appears once for each invocation of a macro
  • 2 = indicates the lines of a macro that have executed. A single line of a macro might cause more than one record to be generated.
  • 3 = indicates which lines of the macro cannot be executed because no code was generated from them. These lines might be either commentary lines or lines that cause no macro code to be generated.
We can see examples of these in the listing shown above. The second and third fields contain the starting and ending record number, and the fourth field contains the name of the macro (you figured that out yourself, right?).

So, record type 1 from our log is telling us that %fred is 18 lines long; record type 3 is telling us that line 17 has no executable elements within it (because it's blank); and the record type 2 lines are telling us which code lines were executed. By implication, lines of code that were not executed don't feature in the mcoverage log. How do we interpret all of this?

The first thing to note is that the line numbers shown in the mcoverage log are relative to the %macro statement and hence don't align with our own line numbers (I deliberately included a blank first and last line in the fred.sas file in order to demonstrate this). The type 2 records show that all lines were executed by our test except 10-12 and 14-17 (these are numbered 11-13 and 15-18 above). Given the logic and the fact that we supplied param=2 when we executed the macro (see yesterday's post), this would seem understandable/correct.

However, surely we can write a quick bit of SAS code to do the brainwork for us and show which lines were executed and which weren't. Of course we can, and I'll show an example program to do this tomorrow...


NOTE: Macros Newness in 9.4 and 9.3 (MCOVERAGE), 6-Jan-2014
NOTE: Macro Coverage in Testing (MCOVERAGE), 7-Jan-2014 (this article!)
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