CONTRIBUTING: Add suggestion about passing pytest flags (#2738)
diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 4ced21b..d9c91bd 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -126,7 +126,8 @@
`--target` can be spelled `-t` in CMake 3.15+. You can also run individual
tests with these targets:
-* `pytest`: Python tests only
+* `pytest`: Python tests only, using the
+[pytest](https://docs.pytest.org/en/stable/) framework
* `cpptest`: C++ tests only
* `test_cmake_build`: Install / subdirectory tests
@@ -134,6 +135,17 @@
`-DPYBIND11_TEST_OVERRIDE="test_callbacks.cpp;test_pickling.cpp"`. If this is
empty, all tests will be built.
+You may also pass flags to the `pytest` target by editing `tests/pytest.ini` or
+by using the `PYTEST_ADDOPTS` environment variable
+(see [`pytest` docs](https://docs.pytest.org/en/2.7.3/customize.html#adding-default-options)). As an example:
+
+```bash
+env PYTEST_ADDOPTS="--capture=no --exitfirst" \
+ cmake --build build --target pytest
+# Or using abbreviated flags
+env PYTEST_ADDOPTS="-s -x" cmake --build build --target pytest
+```
+
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