[Docs][PyOV] Add information about testing pyapi (#14645)

* [Docs][PyOV] Add information about testing pyapi

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src/bindings/python/docs/code_examples.md

@@ -84,7 +84,7 @@ from openvino.helpers.custom_module import top1_index
 ```
 **Do not forget to include a license on the top of each file!** For demonstration purposes, it has been skipped in the snippets above.
 
-To see changes taking effect, rebuild the project (CMake's install step should be good enough <!-- TODO: Add link to BUILDING.md section -->) and run your solution:
+To see the changes take effect, [rebuild the project](../../../../docs/dev/build.md) and run your solution:
 ```python
 import openvino.helpers as ov_helpers
 
@@ -402,9 +402,8 @@ Great! Now the class has reached its destination, from C++, to Python, to Python
 
 This concludes developer work on OpenVINO™ Python API. Don't forget to recompile your builds and have a good time while writing your code!:)
 
-#### Testing out new code
+### Testing the new code
-All of the code is now written. Let's move on to testing.
 
-Please refer to the Test Guide available here:
+Coding is now finished. Let's move on to testing.
 
-    openvino/src/bindings/python/docs/test_examples.md
+To learn how to test your code, refer to the guide on [how to test OpenVINO™ Python API?](./test_examples.md#Running_OpenVINO™_Python_API_tests)

src/bindings/python/docs/contributing.md

@@ -1,15 +1,14 @@
 # Contributing to OpenVINO™ Python API
 
 #### Prerequisites
-*To be added...*
 
 ##### Enviroment
 In case the Python version you have is not supported by OpenVINO, you can refer to [openvino/src/bindings/python/docs/python_version_upgrade.md](https://github.com/openvinotoolkit/openvino/blob/master/src/bindings/python/docs/python_version_upgrade.md) for instructions on how to download and build a newer, supported Python version.
-<!-- TODO: Link to enviroment setup -->
+
-*To be added...*
+The environment setup is described as part of the pyenv example in [the build.md page](./build.md#Example:_using_pyenv_with_OpenVINO™_on_Linux_based_system).
 
 ##### Building
-Building instructions can be found in [BUILDING.md](../BUILDING.md)
+Building instructions can be found in [build.md](./build.md#_Building_the_OpenVINO™_Python_API).
 
 ## Contribution guidelines and best practices
 
@@ -17,14 +16,12 @@ Building instructions can be found in [BUILDING.md](../BUILDING.md)
 It is nothing special... :) First, make sure that all prerequisites are met and focus on writing the code itself. A good starting point is to have some knowledge of the Python language. C++ is also a vital language for OpenVINO™, so it is not a surprise that it is used in this part of the project as well.
 
 Code snippets and detailed explanations can be found here:
-<!-- Link to EXAMPLES -->
+
-    openvino/src/bindings/python/docs/code_example.md
+[Examples of OpenVINO™ Python API code](./code_example.md)
 
 ##### Always test out our code! Don't forget about it before pushing and triggering CIs.
 
-Please refer to Test Guide available here:
+To learn how to test your code, refer to the guide on [how to test OpenVINO™ Python API?](./test_examples.md#Running_OpenVINO™_Python_API_tests)
-
-    openvino/src/bindings/python/docs/test_examples.md
 
 Moreover, the project utilizes *flake8* and *mypy* packages to run codestyle checks. Additionally OpenVINO™ uses the custom configuration file to exclude some strict rules. To run codestyle checks, navigate to the main Python API folder first and use following commands:
 ```shell

src/bindings/python/docs/test_examples.md

@@ -3,18 +3,38 @@
 #### Building and environment
 Instructions can be found in ["Building the OpenVINO™ Python API"](./build.md).
 
-### Running OpenVINO™ Python API tests
+Install the specific requirements file for testing:
+```
+python -m pip install -r openvino/src/bindings/python/requirements_test.txt
+```
+
+Make sure that Python libraries are added to the user environment variables: 
+```
+export PYTHONPATH=PYTHONPATH:<openvino_repo>/bin/intel64/Release/python_api/python3.7
+```
+### Run OpenVINO™ Python API tests
 *For simplicity, all of these commands require to navigate to the main Python API folder first:*
 ```shell
 cd .../openvino/src/bindings/python/
 ```
 
-To run **all tests**:
+To run OpenVINO Python API 2.0 tests:
 ```shell
 pytest tests/
 ```
 
-Test framework *pytest* allows to filter tests with `-k` flag.
+To run OpenVINO Python API 1.0 tests, use this command:
+```
+pytest tests_compatibility/
+```
+
+By default, tests are run on the CPU plugin. If you want to run them on a different plugin,
+you need to specify this environment variable:
+```
+export TEST_DEVICE=GPU
+```
+
+The *pytest* test framework enables you to filter tests with the `-k` flag.
 ```shell
 pytest tests/test_runtime/test_core.py -k "test_available_devices"
 ```
@@ -35,6 +55,31 @@ To run full test suite one can utilize `tox` command:
 tox
 ```
 
+### Check the codestyle of Python API
+There are two packages used in the project to check the codestyle of python code: *mypy* and *flake8*.
+Besides, OpenVINO™ uses a custom configuration file to exclude some strict rules.
+
+To check the codestyle of the Python API 2.0, run the following commands:
+```
+python -m flake8 ./src/openvino/ --config=setup.cfg
+python -m mypy ./src/openvino --config-file ./setup.cfg
+```
+To check the codestyle of the nGraph Python API, run the following commands:
+```
+python -m flake8 ./src/compatibility/ngraph/ --config=setup.cfg
+python -m mypy ./src/compatibility/ngraph --config-file ./setup.cfg
+```
+To check the codestyle of the InferenceEngine Python API, run the following commands:
+```
+cd src/compatibility/openvino
+python -m flake8 ./ --config=setup.cfg
+python -m mypy ./ --config-file ./setup.cfg
+```
+It's recommended to run the mentioned codestyle check whenever new tests are added.
+This check should be executed from the main Python API folder:
+```
+python -m flake8 ./tests/ --config=setup.cfg
+```
 ### Writing OpenVINO™ Python API tests
 ###### Before start
 Follow and complete `openvino/src/bindings/python/docs/code_examples.md`.