Doc for html() builder class (#988)

- Add doc to builder's html element
- Simplify tests (Gui without run())

src/taipy/gui/builder/_element.py

@@ -106,24 +106,59 @@ def __init__(self, *args, **kwargs):
 class html(_Block):
     """A visual element defined as an HTML tag.
 
+    Use this class to integrate raw HTML to your page.
+
     This element can be used as a block element.
     """
 
     def __init__(self, *args, **kwargs):
         """Create a new `html` block.
 
-        TODO
+        Arguments:
+            args (any[]): A list of one or two unnamed arguments:
+
+                - *args[0]* is the HTML tag name. If empty or None, this represents an HTML text
+                  node.
+                - *args[1]* (optional) is the text of this element.<br/>
+                  Note that special HTML characters (such as '&lt;' or '&amp;') do not need to be protected.
+            kwargs (dict[str, any]): the HTML attributes for this element.<br/>
+                These should be valid attribute names, with valid attribute values.
+
+        Examples:
+            - To generate `<br/>`, use:
+               ```
+               html("br")
+               ```
+            - To generate `<h1>My page title</h1>`, use:
+               ```
+               html("h1", "My page title")
+               ```
+            - To generate `<h1 id="page-title">My page title</h1>`, use:
+               ```
+               html("h1", "My page title", id="page-title")
+               ```
+            - To generate `<p>This is a <b>Taipy GUI</b> element.</p>`, use:
+               ```
+               with html("p"):
+                   html(None, "This is a ")
+                   html("b", "Taipy GUI")
+                   html(None, " element.")
+               ```
         """
         super().__init__(*args, **kwargs)
         if not args:
             raise RuntimeError("Can't render html element. Missing html tag name.")
-        self._ELEMENT_NAME = args[0]
+        self._ELEMENT_NAME = args[0] if args[0] else None
         self._content = args[1] if len(args) > 1 else ""
 
     def _render(self, gui: "Gui") -> str:
-        open_tag_attributes = " ".join([f'{k}="{str(v)}"' for k, v in self._properties.items()])
-        open_tag = f"<{self._ELEMENT_NAME} {open_tag_attributes}>"
-        return f"{open_tag}{self._content}{self._render_children(gui)}</{self._ELEMENT_NAME}>"
+        if self._ELEMENT_NAME:
+            attrs = ""
+            if self._properties:
+                attrs = " " + " ".join([f'{k}="{str(v)}"' for k, v in self._properties.items()])
+            return f"<{self._ELEMENT_NAME}{attrs}>{self._content}{self._render_children(gui)}</{self._ELEMENT_NAME}>"
+        else:
+            return self._content
 
 
 class _Control(_Element):

src/taipy/gui/gui.py

@@ -1192,6 +1192,8 @@ def _evaluate_holders(self, expr: str) -> t.List[str]:
         return self.__evaluator.evaluate_holders(self, expr)
 
     def _is_expression(self, expr: str) -> bool:
+        if self.__evaluator is None:
+            return False
         return self.__evaluator._is_expression(expr)
 
     # make components resettable

tests/taipy/gui/builder/control/test_html.py

@@ -25,7 +25,7 @@ def test_html_builder(gui: Gui, test_client, helpers):
         '<h1 style="color:Tomato;">This is a header',
         '<p style="color:green;">This is a paragraph.',
         '<a href="https://www.w3schools.com" target="_blank">a text',
-        "<br >",
-        "<b >This is bold text inside the paragrah.",
+        "<br>",
+        "<b>This is bold text inside the paragrah.",
     ]
     helpers.test_control_builder(gui, page, expected_list)