updates TESTING for COVER_GTT=yesdsilvers/gtt-cover-not-default

1 files changed, 7 insertions, 0 deletions

diff --git a/TESTING b/TESTING
index f9a9b5b..d648c96 100644
--- a/TESTING
+++ b/TESTING
@@ -314,3 +314,10 @@ should be excluded is not, then adjust the `.luacov` file which is the
 configuration for the coverage tool.  This is also loaded by the internal
 in-tree-only module `lib/gitano/coverage.lua` which is generated at build time
 from `lib/gitano/coverage.lua.in`.
+
+If you are trying to get coverage for the `gitano-test-tool` binary in the
+`testing` directory then you will need to **also** pass `COVER_GTT=yes` when
+running the test suite.  This distinction is present since around two thirds of
+all invocations of coverable code in the test suite uses the test tool to
+perform some related task, meaning that covering it causes a significant
+slowdown in testing, and increases the cost of generating the coverage report.