Support bootswatch_theme as parameter to load_css

flask_bootstrap/__init__.py

@@ -89,15 +89,16 @@ def init_app(self, app):
             'row row-cols-lg-auto g-3 align-items-center'
         )  # Bootstrap 5 only
 
-    def load_css(self, version=None, bootstrap_sri=None):
+    def load_css(self, version=None, bootstrap_sri=None, bootswatch_theme=None):
         """Load Bootstrap's css resources with given version.
 
         .. versionadded:: 0.1.0
 
         :param version: The version of Bootstrap.
+        :param bootswatch_theme: Set the bootswatch theme at the request/session level.
         """
         serve_local = current_app.config['BOOTSTRAP_SERVE_LOCAL']
-        bootswatch_theme = current_app.config['BOOTSTRAP_BOOTSWATCH_THEME']
+        bootswatch_theme = bootswatch_theme or current_app.config['BOOTSTRAP_BOOTSWATCH_THEME']
         if version is None:
             version = self.bootstrap_version
         bootstrap_sri = self._get_sri('bootstrap_css', version, bootstrap_sri)

tests/test_bootstrap4/test_bootstrap.py

@@ -38,6 +38,12 @@ def test_load_css_with_default_versions(self, bootstrap):
                         'crossorigin="anonymous">'
         assert bootstrap_css in rv
 
+    def test_load_css_with_bootswatch_theme(self, bootstrap):
+        rv = bootstrap.load_css(bootswatch_theme="mist")
+        bootstrap_css = f'<link rel="stylesheet" href="{CDN_BASE}/bootswatch@{bootstrap.bootstrap_version}/' \
+                        f'dist/mist/bootstrap.min.css"'
+        assert bootstrap_css in rv
+
     def test_load_css_with_non_default_versions(self, bootstrap):
         def _check_assertions(rv):
             assert 'bootstrap.min.css' in rv