Better test support for Python Plugins (#1108)

* add plugins testing utils module

* add plugins manager fixture and init plugins tests helper in conftest

* add _custom_elements attribute to pyscript.Plugin to allow plugins to track the CE they register

* add test for py_tutor

* remove unrelated code from prims js script

* ensure a Plugin always has the app attribute and improve tests

* add tests for py_tutor create_code_section

* implement PluginsManager reset and add teardown on plugins_manager fixture to clean it up after a test

* add test to check if plugin has been registered

* add docstrings to new tests

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* add docstrings to plugins tester

* add changes from main

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* lint

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* add todo to add remaining PluginsManager lifecycle events

Co-authored-by: Fabio Pliger <fpliger@anaconda.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

pyscriptjs/src/plugins/python/py_tutor.py

@@ -90,10 +90,6 @@ class PyTutor:
         # Add the JS file
         script = js.document.createElement("script")
         script.type = "text/javascript"
-        try:
-            script.appendChild(js.document.createTextNode(PAGE_SCRIPT))
-        except BaseException:
-            script.text = PAGE_SCRIPT
         script.src = "./assets/prism/prism.js"
         js.document.head.appendChild(script)