Ignore empty selectors

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## v0.3.20 (TBA)
 
 * Require Elixir 1.13
+* `Premailex.CSSParser.parse/1` now ignores empty selectors
 
 ## v0.3.19 (2023-11-19)
 

lib/premailex/css_parser.ex

@@ -2,6 +2,7 @@ defmodule Premailex.CSSParser do
   @moduledoc """
   Module that handles CSS parsing with naive Regular Expression.
   """
+  require Logger
 
   @type rule :: %{directive: String.t(), value: String.t(), important?: boolean}
   @type rule_set :: %{rules: [rule], selector: String.t(), specificity: number}
@@ -65,12 +66,27 @@ defmodule Premailex.CSSParser do
     selector
     # Ignore escaped commas
     |> String.split(~r/(?<!\\),/)
+    |> normalize_selectors(selector)
     |> Enum.map(&parse_selector_rules(&1, rules))
   end
 
+  defp normalize_selectors(selectors, original) do
+    Enum.reduce(selectors, [], fn selector, acc ->
+      case String.trim(selector) do
+        "" ->
+          Logger.debug("Empty selector found in #{inspect(String.trim(original))}. Ignoring.")
+
+          acc
+
+        selector ->
+          acc ++ [selector]
+      end
+    end)
+  end
+
   defp parse_selector_rules(selector, rules) do
     %{
-      selector: String.trim(selector),
+      selector: selector,
       rules: parse_rules(rules),
       specificity: calculate_specificity(selector)
     }

test/premailex/css_parser_test.exs

@@ -2,6 +2,8 @@ defmodule Premailex.CSSParserTest do
   use ExUnit.Case
   doctest Premailex.CSSParser
 
+  alias ExUnit.CaptureLog
+
   @input """
   body, table {/* text-decoration:underline */background-color:#ffffff;background-image:url('http://example.com/image.png');color:#000000;}
   div p > a:hover {color:#000000 !important;text-decoration:underline}
@@ -19,6 +21,7 @@ defmodule Premailex.CSSParserTest do
          url("/fonts/OpenSans-Regular-webfont.woff") format("woff");
   }
   .with\\,escaped\\,commas {}
+  .with-empty-selector, {}
   """
 
   @parsed [
@@ -60,10 +63,17 @@ defmodule Premailex.CSSParserTest do
       rules: [],
       selector: ".with\\,escaped\\,commas",
       specificity: 1
+    },
+    %{
+      rules: [],
+      selector: ".with-empty-selector",
+      specificity: 1
     }
   ]
 
   test "parse/1" do
-    assert Premailex.CSSParser.parse(@input) == @parsed
+    assert CaptureLog.capture_log(fn ->
+             assert Premailex.CSSParser.parse(@input) == @parsed
+           end) =~ "Empty selector found in \".with-empty-selector,\". Ignoring."
   end
 end

test/premailex/html_inline_styles_test.exs

@@ -12,6 +12,7 @@ defmodule Premailex.HTMLInlineStylesTest do
 
   h1, h2, h3, h4, p {margin: 0; padding: 0;}
   p:first-of-type {font-size:16px;font-weight:bold;}
+  .invalid-empty-selector, {}
   """
 
   @css_inline_content """