Merge branch 'katex-math' into 'master'

Render math in Asciidoc and Markdown with KaTeX using code blocks

Closes #13690 and #13180

See merge request !8003

2 files changed, 122 insertions, 2 deletions

diff --git a/spec/lib/banzai/filter/math_filter_spec.rb b/spec/lib/banzai/filter/math_filter_spec.rb
new file mode 100644
index 00000000000..3fe2c7f5d5d
--- /dev/null
+++ b/spec/lib/banzai/filter/math_filter_spec.rb
@@ -0,0 +1,120 @@
+require 'spec_helper'
+
+describe Banzai::Filter::MathFilter, lib: true do
+  include FilterSpecHelper
+
+  it 'leaves regular inline code unchanged' do
+    input = "<code>2+2</code>"
+    doc = filter(input)
+
+    expect(doc.to_s).to eq input
+  end
+
+  it 'removes surrounding dollar signs and adds class code, math and js-render-math' do
+    doc = filter("$<code>2+2</code>$")
+
+    expect(doc.to_s).to eq '<code class="code math js-render-math" data-math-style="inline">2+2</code>'
+  end
+
+  it 'only removes surrounding dollar signs' do
+    doc = filter("test $<code>2+2</code>$ test")
+    before = doc.xpath('descendant-or-self::text()[1]').first
+    after = doc.xpath('descendant-or-self::text()[3]').first
+
+    expect(before.to_s).to eq 'test '
+    expect(after.to_s).to eq ' test'
+  end
+
+  it 'only removes surrounding single dollar sign' do
+    doc = filter("test $$<code>2+2</code>$$ test")
+    before = doc.xpath('descendant-or-self::text()[1]').first
+    after = doc.xpath('descendant-or-self::text()[3]').first
+
+    expect(before.to_s).to eq 'test $'
+    expect(after.to_s).to eq '$ test'
+  end
+
+  it 'adds data-math-style inline attribute to inline math' do
+    doc = filter('$<code>2+2</code>$')
+    code = doc.xpath('descendant-or-self::code').first
+
+    expect(code['data-math-style']).to eq 'inline'
+  end
+
+  it 'adds class code and math to inline math' do
+    doc = filter('$<code>2+2</code>$')
+    code = doc.xpath('descendant-or-self::code').first
+
+    expect(code[:class]).to include("code")
+    expect(code[:class]).to include("math")
+  end
+
+  it 'adds js-render-math class to inline math' do
+    doc = filter('$<code>2+2</code>$')
+    code = doc.xpath('descendant-or-self::code').first
+
+    expect(code[:class]).to include("js-render-math")
+  end
+
+  # Cases with faulty syntax. Should be a no-op
+
+  it 'ignores cases with missing dolar sign at the end' do
+    input = "test $<code>2+2</code> test"
+    doc = filter(input)
+
+    expect(doc.to_s).to eq input
+  end
+
+  it 'ignores cases with missing dolar sign at the beginning' do
+    input = "test <code>2+2</code>$ test"
+    doc = filter(input)
+
+    expect(doc.to_s).to eq input
+  end
+
+  it 'ignores dollar signs if it is not adjacent' do
+    input = '<p>We check strictly $<code>2+2</code> and  <code>2+2</code>$ </p>'
+    doc = filter(input)
+
+    expect(doc.to_s).to eq input
+  end
+
+  # Display math
+
+  it 'adds data-math-style display attribute to display math' do
+    doc = filter('<pre class="code highlight js-syntax-highlight math" v-pre="true"><code>2+2</code></pre>')
+    pre = doc.xpath('descendant-or-self::pre').first
+
+    expect(pre['data-math-style']).to eq 'display'
+  end
+
+  it 'adds js-render-math class to display math' do
+    doc = filter('<pre class="code highlight js-syntax-highlight math" v-pre="true"><code>2+2</code></pre>')
+    pre = doc.xpath('descendant-or-self::pre').first
+
+    expect(pre[:class]).to include("js-render-math")
+  end
+
+  it 'ignores code blocks that are not math' do
+    input = '<pre class="code highlight js-syntax-highlight plaintext" v-pre="true"><code>2+2</code></pre>'
+    doc = filter(input)
+
+    expect(doc.to_s).to eq input
+  end
+
+  it 'requires the pre to contain both code and math' do
+    input = '<pre class="highlight js-syntax-highlight plaintext math" v-pre="true"><code>2+2</code></pre>'
+    doc = filter(input)
+
+    expect(doc.to_s).to eq input
+  end
+
+  it 'dollar signs around to display math' do
+    doc = filter('$<pre class="code highlight js-syntax-highlight math" v-pre="true"><code>2+2</code></pre>$')
+    before = doc.xpath('descendant-or-self::text()[1]').first
+    after = doc.xpath('descendant-or-self::text()[3]').first
+
+    expect(before.to_s).to eq '$'
+    expect(after.to_s).to eq '$'
+  end
+end
diff --git a/spec/lib/gitlab/asciidoc_spec.rb b/spec/lib/gitlab/asciidoc_spec.rb
index 4aba783dc33..f3843ca64ff 100644
--- a/spec/lib/gitlab/asciidoc_spec.rb
+++ b/spec/lib/gitlab/asciidoc_spec.rb
@@ -11,7 +11,7 @@ module Gitlab
       it "converts the input using Asciidoctor and default options" do
         expected_asciidoc_opts = {
             safe: :secure,
-            backend: :html5,
+            backend: :gitlab_html5,
             attributes: described_class::DEFAULT_ADOC_ATTRS
         }
 
@@ -27,7 +27,7 @@ module Gitlab
         it "merges the options with default ones" do
           expected_asciidoc_opts = {
               safe: :safe,
-              backend: :html5,
+              backend: :gitlab_html5,
               attributes: described_class::DEFAULT_ADOC_ATTRS + ['foo']
           }