built new beautifulsoup function to apply

html tags to markdown file once processed
with test cases.

tests/app/main/test_formatters.py

@@ -7,6 +7,7 @@ from freezegun import freeze_time
 
 from app.formatters import (
     convert_markdown_template,
+    apply_html_class,
     email_safe,
     format_datetime_relative,
     format_delta,
@@ -181,3 +182,7 @@ def test_markdown_format(fake_markdown_file):
     app = Flask("app")
     with app.app_context():
         assert convert_markdown_template(fake_markdown_file, test=True) == "<h1>Test</h1>"
+
+@pytest.mark.usefixtures("fake_soup_template")
+def test_soup_format(fake_soup_template):
+    assert apply_html_class([['h1', 'testClass']], fake_soup_template) == '<h1 class="testClass">Test</h1>'