update contributing.md

1 files changed, 7 insertions, 0 deletions

diff --git a/contributing.md b/contributing.md
index 7dedaa7..0faed2b 100644
--- a/contributing.md
+++ b/contributing.md
@@ -855,6 +855,11 @@ that you can click on to open them.
   parameter of `TEST()` / `TEST_F()` macro)
 - Test source files match their suite name (or test fixture name in the case of
   tests that use a fixture)
+- Tests that measure time or use delays must be [disabled][gtest-disable] (by
+  prepending `DISABLED_` to the suite or case name).
+
+  These tests will still be compiled, but will only run when the `test_main`
+  binary is run with the `--gtest_also_run_disabled_tests` flag.
 
 # Structure
 
@@ -1017,3 +1022,5 @@ points should be kept in mind:
 - When adding new libraries, please update the library version table in
   [readme\.md](./readme.md)
 
+[gtest-disable]: https://google.github.io/googletest/advanced.html#temporarily-disabling-tests
+