Add instructions on running the tests (#26)

docs/contributing/run_tests.md

@@ -0,0 +1,38 @@
+# Run the test suite
+
+The configuration for running the tests is included in `Makefile`. Only running the tests against an existing installation is supported:
+
+```console
+make -j$(nproc)
+sudo make install
+make installcheck
+```
+
+## Troubleshooting
+
+### Invalid locale settings
+
+```text
+initdb: invalid locale settings; check LANG and LC_* environment variables
+```
+
+The locale settings can be set (to en_US.UTF-8 in the example) as follows ([source](https://www.thomas-krenn.com/en/wiki/Perl_warning_Setting_locale_failed_in_Debian)):
+
+```console
+export LANGUAGE=en_US.UTF-8
+export LANG=en_US.UTF-8
+export LC_ALL=en_US.UTF-8
+locale-gen en_US.UTF-8
+dpkg-reconfigure locales
+```
+
+The `dpkg-reconfigure locales` command will open a dialog under Debian for selecting the desired locale.
+
+### Invalid permissions
+
+```text
+FATAL:  data directory "/clone_path/./regress/instance/data" has invalid permissions
+DETAIL:  Permissions should be u=rwx (0700) or u=rwx,g=rx (0750).
+```
+
+When using Vagrant, directories created in synced folders don't respect umask. The Apache AGE source code needs to be cloned to an unsynced directory for running the tests.

docs/index.rst

@@ -55,3 +55,9 @@ Apache AGE's documentation
    advanced/plpgsql
    advanced/sql_in_cypher
 
+.. toctree::
+   :caption: Contributing
+   :maxdepth: 1
+
+   contributing/run_tests
+