Patch >2-digit tag-count padding in base reporter

[TysonRayJones]

Hello beautiful Catch2 team!

This PR patches a minor formatting bug in the base reporter due to this line in catch_reporter_helpers.cpp, which includes:

std::setw( 2 ) << tagCount.count

Passing the CLI argument --list-tags outputs a list like:

All available tags:
  11  [mytag]
   4  [myothertag]
2 tags

However, the width of the tag-count column was previously hardcoded to 2 (as per the line above), such that the formatting broke (with the tag names awkwardly misaligned/displaced) for 3+ digit tag counts. This occurred whenever a tag contains one hundred or more tests (like in my use-case for scientific software tests), and would result in formatting like:

All available tags:
  11  [mytag]
  100  [myjumbotag]
   4  [myothertag]
  4312  [myunbelievablypopulartag]
3 tags

This patch pre-computes the maximum number of digits among the tag counts, expanding the padding when there are more than 100 tests in a tag (and handling when tags are empty). It now outputs e.g.

All available tags:
    11  [mytag]
   100  [myjumbotag]
     4  [myothertag]
  4312  [myunbelievablypopulartag]
3 tags

I have endeavoured to replicate the format of clang-format, modelled from a code snippet just above the diff performing a similar chore (defaultListListeners choosing the padding of the listener name column). Note I used an explicit size_t type over auto for the "main" variable maxTagCountLen to inform the static_cast, necessarily because std::floor returns a non-integral type (e.g. double) which cannot be passed to std::setw.

This abominable MWE can be used to generate many same-tag tests to check the formatting:

#include <catch2/catch_test_macros.hpp>

// Mn(tag) instantiates 3^(n-1) uniquely-named tests with the given tag
#define M1( name, tag ) TEST_CASE( name, tag ) { }
#define M2( name, tag ) M1( name, tag ) M1( name "a", tag ) M1( name "aa", tag )
#define M3( name, tag ) M2( name, tag ) M2( name "b", tag ) M2( name "bb", tag )
#define M4( name, tag ) M3( name, tag ) M3( name "c", tag ) M3( name "cc", tag )
#define M5( name, tag ) M4( name, tag ) M4( name "d", tag ) M4( name "dd", tag )
#define M6( name, tag ) M5( name, tag ) M5( name "e", tag ) M5( name "ee", tag )
#define M7( name, tag ) M6( name, tag ) M6( name "f", tag ) M6( name "ff", tag )
#define M8( name, tag ) M7( name, tag ) M7( name "g", tag ) M7( name "gg", tag )

// invoke as many macros as you dare!
M1("1", "[tag1]");
M2("2", "[tag2]");
M3("3", "[tag3]");
M4("4", "[tag4]");
M5("5", "[tag5]");
M6("6", "[tag6]"); // bug visible from M6
M7("7", "[tag7]");
M8("8", "[tag8]");

// then run ./exec --list-tags

Previously this MWE would erroneously output:

All available tags:
  1   [tag1]
  3   [tag2]
  9   [tag3]
  27  [tag4]
  81  [tag5]
  243  [tag6]
  729  [tag7]
  2187  [tag8]
8 tags

but under this patch, now outputs:

All available tags:
     1  [tag1]
     3  [tag2]
     9  [tag3]
    27  [tag4]
    81  [tag5]
   243  [tag6]
   729  [tag7]
  2187  [tag8]
8 tags

Finally, invoking no macros correctly outputs:

All available tags:
0 tags

All things considered, this solves an extremely minor issue, but I'm thrilled in any case to be able to give back to a project I adore!
Tyson

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.99%. Comparing base (76f70b1) to head (0c72039).

Additional details and impacted files

@@            Coverage Diff             @@
##            devel    #2963      +/-   ##
==========================================
+ Coverage   90.98%   90.99%   +0.01%     
==========================================
  Files         198      198              
  Lines        8599     8609      +10     
==========================================
+ Hits         7823     7833      +10     
  Misses        776      776              

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[shahsb]

LGTM.