[PATCH v9 03/21] dts: add basic developer docs

["Juraj Linkeš" <juraj.linkes@pantheon.tech>]

Expand the framework contribution guidelines and add how to document the
code with Python docstrings.

Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
---
 doc/guides/tools/dts.rst | 73 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/doc/guides/tools/dts.rst b/doc/guides/tools/dts.rst
index 32c18ee472..cd771a428c 100644
--- a/doc/guides/tools/dts.rst
+++ b/doc/guides/tools/dts.rst
@@ -264,6 +264,65 @@ which be changed with the ``--output-dir`` command line argument.
 The results contain basic statistics of passed/failed test cases and DPDK version.
 
 
+Contributing to DTS
+-------------------
+
+There are two areas of contribution: The DTS framework and DTS test suites.
+
+The framework contains the logic needed to run test cases, such as connecting to nodes,
+running DPDK apps and collecting results.
+
+The test cases call APIs from the framework to test their scenarios. Adding test cases may
+require adding code to the framework as well.
+
+
+Framework Coding Guidelines
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When adding code to the DTS framework, pay attention to the rest of the code
+and try not to divert much from it. The :ref:`DTS developer tools <dts_dev_tools>` will issue
+warnings when some of the basics are not met.
+
+The code must be properly documented with docstrings. The style must conform to
+the `Google style <https://google.github.io/styleguide/pyguide.html#38-comments-and-docstrings>`_.
+See an example of the style
+`here <https://www.sphinx-doc.org/en/master/usage/extensions/example_google.html>`_.
+For cases which are not covered by the Google style, refer
+to `PEP 257 <https://peps.python.org/pep-0257/>`_. There are some cases which are not covered by
+the two style guides, where we deviate or where some additional clarification is helpful:
+
+   * The __init__() methods of classes are documented separately from the docstring of the class
+     itself.
+   * The docstrigs of implemented abstract methods should refer to the superclass's definition
+     if there's no deviation.
+   * Instance variables/attributes should be documented in the docstring of the class
+     in the ``Attributes:`` section.
+   * The dataclass.dataclass decorator changes how the attributes are processed. The dataclass
+     attributes which result in instance variables/attributes should also be recorded
+     in the ``Attributes:`` section.
+   * Class variables/attributes, on the other hand, should be documented with ``#:`` above
+     the type annotated line. The description may be omitted if the meaning is obvious.
+   * The Enum and TypedDict also process the attributes in particular ways and should be documented
+     with ``#:`` as well. This is mainly so that the autogenerated docs contain the assigned value.
+   * When referencing a parameter of a function or a method in their docstring, don't use
+     any articles and put the parameter into single backticks. This mimics the style of
+     `Python's documentation <https://docs.python.org/3/index.html>`_.
+   * When specifying a value, use double backticks::
+
+        def foo(greet: bool) -> None:
+            """Demonstration of single and double backticks.
+
+            `greet` controls whether ``Hello World`` is printed.
+
+            Args:
+               greet: Whether to print the ``Hello World`` message.
+            """
+            if greet:
+               print(f"Hello World")
+
+   * The docstring maximum line length is the same as the code maximum line length.
+
+
 How To Write a Test Suite
 -------------------------
 
@@ -293,6 +352,18 @@ There are four types of methods that comprise a test suite:
    | These methods don't need to be implemented if there's no need for them in a test suite.
      In that case, nothing will happen when they're is executed.
 
+#. **Configuration, traffic and other logic**
+
+   The ``TestSuite`` class contains a variety of methods for anything that
+   a test suite setup, a teardown, or a test case may need to do.
+
+   The test suites also frequently use a DPDK app, such as testpmd, in interactive mode
+   and use the interactive shell instances directly.
+
+   These are the two main ways to call the framework logic in test suites. If there's any
+   functionality or logic missing from the framework, it should be implemented so that
+   the test suites can use one of these two ways.
+
 #. **Test case verification**
 
    Test case verification should be done with the ``verify`` method, which records the result.
@@ -308,6 +379,8 @@ There are four types of methods that comprise a test suite:
    and used by the test suite via the ``sut_node`` field.
 
 
+.. _dts_dev_tools:
+
 DTS Developer Tools
 -------------------
 
-- 
2.34.1