[docs] add sample commands for test exec

README.md

@@ -15,4 +15,8 @@ For bug reports, mailing list, and other information please visit:
 
 For license information, see the file COPYING.
 
+For build information, see the file BUILD.md.
+
+For test execution, see the file TESTING.md.
+
 Documentation: https://harfbuzz.github.io

TESTING.md

@@ -0,0 +1,47 @@
+## Build & Run
+
+Depending on what area you are working in change or add `HB_DEBUG_<whatever>`.
+Values defined in `hb-debug.hh`.
+
+```shell
+# quick sanity check
+time (make CPPFLAGS='-DHB_DEBUG_SUBSET=100' \
+  && make -C test/api check || cat test/api/test-suite.log)
+
+# slower santiy check
+time (make CPPFLAGS='-DHB_DEBUG_SUBSET=100' \
+   && make -C src check \
+   && make -C test/api check \
+   && make -C test/subset check)
+
+# confirm you didn't break anything else
+time (make CPPFLAGS='-DHB_DEBUG_SUBSET=100' \
+  && make check)
+
+# often catches files you didn't add, e.g. test fonts to EXTRA_DIST
+make distcheck
+```
+
+### Debug with GDB
+
+```
+cd ./util
+../libtool --mode=execute gdb --args ./hb-subset ...
+```
+
+### Enable Debug Logging
+
+```shell
+# make clean if you previously build w/o debug logging
+make CPPFLAGS=-DHB_DEBUG_SUBSET=100
+```
+
+## Build and Test via CMake
+
+Note: You'll need to first install ninja-build via apt-get.
+
+```shell
+cd harfbuzz
+mkdir buid
+cmake -DHB_CHECK=ON -Bbuild -H. -GNinja && ninja -Cbuild && CTEST_OUTPUT_ON_FAILURE=1 ninja -Cbuild test
+```