1 files changed, 27 insertions, 0 deletions
diff --git a/spec/lib/banzai/filter/pathological_markdown_filter_spec.rb b/spec/lib/banzai/filter/pathological_markdown_filter_spec.rb
new file mode 100644
index 00000000000..e0a07d1ea77
--- /dev/null
+++ b/spec/lib/banzai/filter/pathological_markdown_filter_spec.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Banzai::Filter::PathologicalMarkdownFilter do
+  include FilterSpecHelper
+
+  let_it_be(:short_text) { '![a' * 5 }
+  let_it_be(:long_text) { ([short_text] * 10).join(' ') }
+  let_it_be(:with_images_text) { "![One ![one](one.jpg) #{'and\n' * 200} ![two ![two](two.jpg)" }
+
+  it 'detects a significat number of unclosed image links' do
+    msg = <<~TEXT
+      _Unable to render markdown - too many unclosed markdown image links detected._
+    TEXT
+
+    expect(filter(long_text)).to eq(msg.strip)
+  end
+
+  it 'does nothing when there are only a few unclosed image links' do
+    expect(filter(short_text)).to eq(short_text)
+  end
+
+  it 'does nothing when there are only a few unclosed image links and images' do
+    expect(filter(with_images_text)).to eq(with_images_text)
+  end
+end