[doc] add guidelines about running regression tests

docs/source/dev_manual/index.rst

@@ -5,3 +5,5 @@
    ci_cd_setup/index
 
    version_number
+
+   regression_tests

docs/source/dev_manual/regression_tests.rst

@@ -0,0 +1,46 @@
+.. dev_manual_regression_tests::
+
+Regression Tests
+================
+
+Regression tests are designed to cover various technical features of the OpenFPGA projects, including but not limited to
+
+- Netlist generation
+- Netlist verification
+- Bitstream generation
+
+Considering the large number of technical features, regression tests are categorized into several groups, which can be found at ``openfpga_flow/regression_test_scripts/``
+
+Run a Test
+----------
+
+To run a regression test, users can execute a shell script (assume you are under the root directory of the project), for example, 
+
+```
+./openfpga_flow/regression_test_scripts/basic_reg_test.sh [OPTIONS]
+```
+
+.. note:: ``basic_reg_test`` can be replaced by other tests which are under ``openfpga_flow/regression_test_scripts/``
+
+Test Options
+------------
+
+There are a few options available when running the tests.
+
+.. option:: --debug
+
+  This option can turn on debug mode when running regression tests. By default it is ``off``.
+
+.. option:: --show_thread_logs
+
+  This option can enable verbose output when running regression tests. By default it is ``off``.
+
+.. note:: To avoid massive outputs, suggest to run the tests with default options. In CI, always recommend to turn on the debug and verbose options
+
+.. option:: --remove_run_dir all
+
+  This option is to remove all the previous run results for a specific regression test. Suggest to use when there are limited disk space.
+
+  .. note:: Be careful before using this option! It may cause permanent loss on test results.
+
+