feat: add docs and test for trix post processor

core/frameworks/pixel/trix_post_processor.ex

@@ -7,6 +7,12 @@ defmodule Frameworks.Pixel.TrixPostProcessor do
   @doc """
   Adds `target="_blank"` to any `<a>` tags that do not already have it.
   It returns the modified HTML content.
+
+  ## Regex Breakdown:
+  - `<a`: Matches the opening part of an <a> tag.
+  - `(?![^>]*target=)`: Negative lookahead to ensure the <a> tag does not already have a `target` attribute.
+  - `[^>]*`: Ensures that no characters up to the closing `>` of the tag contain `target=`.
+  - `([^>]*)`: Captures the remaining attributes inside the <a> tag.
   """
   def add_target_blank(html_content) do
     Regex.replace(~r/<a(?![^>]*target=)([^>]*)>/, html_content, "<a\\1 target=\"_blank\">")

core/test/frameworks/pixel/trix_post_processor_test.exs

@@ -0,0 +1,40 @@
+defmodule Frameworks.Pixel.TrixPostProcessorTest do
+  use ExUnit.Case
+  alias Frameworks.Pixel.TrixPostProcessor
+
+  describe "add_target_blank/1" do
+    test "adds target=_blank to <a> tags without target attribute" do
+      html_content = "<a href=\"http://example.com\">Example</a>"
+      expected = "<a href=\"http://example.com\" target=\"_blank\">Example</a>"
+      assert TrixPostProcessor.add_target_blank(html_content) == expected
+    end
+
+    test "does not modify <a> tags with existing target attribute" do
+      html_content = "<a href=\"http://example.com\" target=\"_self\">Example</a>"
+      expected = "<a href=\"http://example.com\" target=\"_self\">Example</a>"
+      assert TrixPostProcessor.add_target_blank(html_content) == expected
+    end
+
+    test "adds target=_blank to multiple <a> tags without target attribute" do
+      html_content =
+        "<a href=\"http://example1.com\">Example1</a> <a href=\"http://example2.com\">Example2</a>"
+
+      expected =
+        "<a href=\"http://example1.com\" target=\"_blank\">Example1</a> <a href=\"http://example2.com\" target=\"_blank\">Example2</a>"
+
+      assert TrixPostProcessor.add_target_blank(html_content) == expected
+    end
+
+    test "handles nested <a> tags correctly" do
+      html_content = "<div><a href=\"http://example.com\">Example</a></div>"
+      expected = "<div><a href=\"http://example.com\" target=\"_blank\">Example</a></div>"
+      assert TrixPostProcessor.add_target_blank(html_content) == expected
+    end
+
+    test "returns the same content if no <a> tags are present" do
+      html_content = "<p>No links here</p>"
+      expected = "<p>No links here</p>"
+      assert TrixPostProcessor.add_target_blank(html_content) == expected
+    end
+  end
+end