Deprecate py-mount Attribute (#1330)

* Deprecate py-mount attribute, with comments as to when it was deprecated

* Add changelog entry for deprecation

* Fix 'unused' examples that used py-mount (handtrack and mario)

pyscriptjs/src/components/pyscript.ts

@@ -237,6 +237,13 @@ export async function mountElements(interpreter: InterpreterClient) {
     const matches: NodeListOf<HTMLElement> = document.querySelectorAll('[py-mount]');
     logger.info(`py-mount: found ${matches.length} elements`);
 
+    if (matches.length > 0) {
+        //last non-deprecated version: 2023.03.1
+        const deprecationMessage =
+            'The "py-mount" attribute is deprecated. Please add references to HTML Elements manually in your script.';
+        createDeprecationWarning(deprecationMessage, 'py-mount');
+    }
+
     let source = '';
     for (const el of matches) {
         const mountName = el.getAttribute('py-mount') || el.id.split('-').join('_');

pyscriptjs/tests/integration/test_01_basic.py

@@ -345,3 +345,17 @@ class TestBasic(PyScriptTest):
         btn.click()
         assert self.console.log.lines[-1] == "hello world!"
         assert self.console.error.lines == []
+
+    def test_py_mount_shows_deprecation_warning(self):
+        # last non-deprecated version: 2023.03.1
+        self.pyscript_run(
+            """
+            <div id="foo" py-mount></div>
+            """
+        )
+        banner = self.page.locator(".alert-banner")
+        expected_message = (
+            'The "py-mount" attribute is deprecated. '
+            + "Please add references to HTML Elements manually in your script."
+        )
+        assert banner.inner_text() == expected_message