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diff --git a/spec/lib/banzai/filter/truncate_visible_filter_spec.rb b/spec/lib/banzai/filter/truncate_visible_filter_spec.rb
new file mode 100644
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+++ b/spec/lib/banzai/filter/truncate_visible_filter_spec.rb
@@ -0,0 +1,128 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Banzai::Filter::TruncateVisibleFilter do
+  include FilterSpecHelper
+
+  let_it_be(:project) { build(:project, :repository) }
+  let_it_be(:max_chars) { 100 }
+  let_it_be(:user) do
+    user = create(:user, username: 'gfm')
+    project.add_maintainer(user)
+    user
+  end
+
+  # Since we're truncating nodes of an html document, actually use the
+  # full pipeline to generate full documents.
+  def convert_markdown(text, context = {})
+    Banzai::Pipeline::FullPipeline.to_html(text, { project: project }.merge(context))
+  end
+
+  shared_examples_for 'truncates text' do
+    specify do
+      html = convert_markdown(markdown)
+      doc = filter(html, { truncate_visible_max_chars: max_chars })
+
+      expect(doc.to_html).to match(expected)
+    end
+  end
+
+  describe 'displays inline code' do
+    let(:markdown) { 'Text with `inline code`' }
+    let(:expected) { 'Text with <code>inline code</code>' }
+
+    it_behaves_like 'truncates text'
+  end
+
+  describe 'truncates the text with multiple paragraphs' do
+    let(:markdown) { "Paragraph 1\n\nParagraph 2" }
+    let(:expected) { 'Paragraph 1...' }
+
+    it_behaves_like 'truncates text'
+  end
+
+  describe 'truncates the first line of a code block' do
+    let(:markdown) { "```\nCode block\nwith two lines\n```" }
+    let(:expected) { "Code block...</span>\n</code>" }
+
+    it_behaves_like 'truncates text'
+  end
+
+  describe 'preserves code color scheme' do
+    let(:max_chars) { 150 }
+    let(:markdown) { "```ruby\ndef test\n  'hello world'\nend\n```" }
+    let(:expected) do
+      '<code><span id="LC1" class="line" lang="ruby">' \
+      '<span class="k">def</span> <span class="nf">test</span>...</span>'
+    end
+
+    it_behaves_like 'truncates text'
+  end
+
+  describe 'truncates a single long line of text' do
+    let(:max_chars) { 150 }
+    let(:text) { 'The quick brown fox jumped over the lazy dog twice' } # 50 chars
+    let(:markdown) { text * 4 }
+    let(:expected) { (text * 2).sub(/.{3}/, '...') }
+
+    it_behaves_like 'truncates text'
+  end
+
+  it 'preserves a link href when link text is truncated' do
+    max_chars = 150
+    text = 'The quick brown fox jumped over the lazy dog' # 44 chars
+    link_url = 'http://example.com/foo/bar/baz' # 30 chars
+    markdown = "#{text}#{text}#{text} #{link_url}" # 163 chars
+    expected_link_text = 'http://example...</a>'
+
+    html = convert_markdown(markdown)
+    doc = filter(html, { truncate_visible_max_chars: max_chars })
+
+    expect(doc.to_html).to match(link_url)
+    expect(doc.to_html).to match(expected_link_text)
+  end
+
+  it 'truncates HTML properly' do
+    markdown = "@#{user.username}, can you look at this?\nHello world\n"
+
+    html = convert_markdown(markdown)
+    doc = filter(html, { truncate_visible_max_chars: max_chars })
+
+    # Make sure we didn't create invalid markup
+    expect(doc.errors).to be_empty
+
+    # Leading user link
+    expect(doc.css('a').length).to eq(1)
+    expect(doc.css('a')[0].attr('href')).to eq urls.user_path(user)
+    expect(doc.css('a')[0].text).to eq "@#{user.username}"
+    expect(doc.content).to eq "@#{user.username}, can you look at this?..."
+  end
+
+  it 'truncates HTML with emoji properly' do
+    markdown = "foo :wink:\nbar :grinning:"
+    # actual = first_line_in_markdown(object, attribute, 100, project: project)
+
+    html = convert_markdown(markdown)
+    doc = filter(html, { truncate_visible_max_chars: max_chars })
+
+    # Make sure we didn't create invalid markup
+    # But also account for the 2 errors caused by the unknown `gl-emoji` elements
+    expect(doc.errors.length).to eq(2)
+
+    expect(doc.css('gl-emoji').length).to eq(2)
+    expect(doc.css('gl-emoji')[0].attr('data-name')).to eq 'wink'
+    expect(doc.css('gl-emoji')[1].attr('data-name')).to eq 'grinning'
+
+    expect(doc.content).to eq "foo 😉\nbar 😀"
+  end
+
+  it 'does not truncate if truncate_visible_max_chars not specified' do
+    markdown = "@#{user.username}, can you look at this?\nHello world"
+
+    html = convert_markdown(markdown)
+    doc = filter(html)
+
+    expect(doc.content).to eq markdown
+  end
+end