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/tests/py-unit/pyscript_plugins_tester.py

@@ -0,0 +1,119 @@
+import xml.dom
+from xml.dom.minidom import Node  # nosec
+
+import pyscript
+
+
+class classList:
+    """Class that (lightly) emulates the behaviour of HTML Nodes ClassList"""
+
+    def __init__(self):
+        self._classes = []
+
+    def add(self, classname: str):
+        """Add classname to the classList"""
+        self._classes.append(classname)
+
+    def remove(self, classname: str):
+        """Remove classname from the classList"""
+        self._classes.remove(classname)
+
+
+class PluginsManager:
+    """
+    Emulator of PyScript PluginsManager that can be used to simulate plugins lifecycle events
+
+    TODO: Currently missing most of the lifecycle events in PluginsManager implementation. Need
+        to add more than just addPythonPlugin
+    """
+
+    def __init__(self):
+        self.plugins = []
+
+        # mapping containing all the custom elements createed by plugins
+        self._custom_elements = {}
+
+    def addPythonPlugin(self, pluginInstance: pyscript.Plugin):
+        """
+        Add a pluginInstance to the plugins managed by the PluginManager and calls
+        pluginInstance.init(self) to initialized the plugin with the manager
+        """
+        pluginInstance.init(self)
+        self.plugins.append(pluginInstance)
+
+    def reset(self):
+        """
+        Unregister all plugins and related custom elements.
+        """
+        for plugin in self.plugins:
+            plugin.app = None
+
+        self.plugins = []
+        self._custom_elements = {}
+
+
+class CustomElement:
+    def __init__(self, plugin_class: pyscript.Plugin):
+        self.pyPluginInstance = plugin_class(self)
+        self.attributes = {}
+        self.innerHTML = ""
+
+    def connectedCallback(self):
+        return self.pyPluginInstance.connect()
+
+    def getAttribute(self, attr: str):
+        return self.attributes.get(attr)
+
+
+def define_custom_element(tag, plugin_class: pyscript.Plugin):
+    """
+    Mock method to emulate the behaviour of the PyScript `define_custom_element`
+    that basically creates a new CustomElement passing plugin_class as Python
+    proxy object. For more info check out the logic of the original implementation at:
+
+    src/plugin.ts:define_custom_element
+    """
+    ce = CustomElement(plugin_class)
+    plugins_manager._custom_elements[tag] = ce
+
+
+plugins_manager = PluginsManager()
+
+# Init pyscript testing mocks
+impl = xml.dom.getDOMImplementation()
+
+
+class Node:
+    """
+    Represent an HTML Node.
+
+    This classes us an abstraction on top of xml.dom.minidom.Node
+    """
+
+    def __init__(self, el: Node):
+        self._el = el
+        self.classList = classList()
+
+    # Automatic delegation is a simple and short boilerplate:
+    def __getattr__(self, attr: str):
+        return getattr(self._el, attr)
+
+    def createElement(self, *args, **kws):
+        newEl = self._el.createElement(*args, **kws)
+        return Node(newEl)
+
+
+class Document(Node):
+    """
+    Represent an HTML Document.
+
+    This classes us an abstraction on top of xml.dom.minidom.Document
+    """
+
+    def __init__(self):
+        self._el = impl.createDocument(None, "document", None)
+
+
+pyscript.js.document = doc = Document()
+pyscript.js.document.head = doc.createElement("head")
+pyscript.js.document.body = doc.createElement("body")