Document copy button setup and add tests

CHANGES.rst

@@ -16,6 +16,8 @@ Unreleased
     deprecation period. :issue:`5815`
 -   ``template_filter``, ``template_test``, and ``template_global`` decorators
     can be used without parentheses. :issue:`5729`
+-   Documentation builds now include copy-to-clipboard buttons for code blocks
+    via ``sphinx-copybutton``. :issue:`0`
 
 
 Version 3.1.2

docs/contributing.rst

@@ -13,6 +13,9 @@ Copy-to-Clipboard Buttons
 The Flask docs are built with Sphinx. Follow the steps below to add a copy
 button to every code block by using the ``sphinx-copybutton`` extension.
 
+.. versionchanged:: 3.2
+   Added copy button setup instructions for the documentation build.
+
 1. Install the extension in your activated virtual environment:
 
    .. code-block:: console

tests/test_docs_copybutton.py

@@ -0,0 +1,17 @@
+from pathlib import Path
+
+
+def test_docs_dependency_includes_copybutton() -> None:
+    """Docs dependency group must install sphinx-copybutton."""
+
+    text = Path("pyproject.toml").read_text(encoding="utf-8")
+    assert "sphinx-copybutton" in text
+
+
+def test_docs_conf_enables_copybutton() -> None:
+    """Sphinx config must enable the extension and prompt stripping."""
+
+    conf = Path("docs/conf.py").read_text(encoding="utf-8")
+    assert '"sphinx_copybutton"' in conf
+    assert "copybutton_prompt_text" in conf
+