PlantUML support for Markdown

Allow rendering of PlantUML diagrams in Markdown documents using fenced blocks:

    ```plantuml
    Bob -> Sara : Hello
    Sara -> Bob : Go away
    ```

Closes: #4048

1 files changed, 32 insertions, 0 deletions

diff --git a/spec/lib/banzai/filter/plantuml_filter_spec.rb b/spec/lib/banzai/filter/plantuml_filter_spec.rb
new file mode 100644
index 00000000000..f85a5dcbd8b
--- /dev/null
+++ b/spec/lib/banzai/filter/plantuml_filter_spec.rb
@@ -0,0 +1,32 @@
+require 'spec_helper'
+
+describe Banzai::Filter::PlantumlFilter, lib: true do
+  include FilterSpecHelper
+
+  it 'should replace plantuml pre tag with img tag' do
+    stub_application_setting(plantuml_enabled: true, plantuml_url: "http://localhost:8080")
+    input = '<pre class="plantuml"><code>Bob -> Sara : Hello</code><pre>'
+    output = '<div class="imageblock"><div class="content"><img class="plantuml" src="http://localhost:8080/png/U9npoazIqBLJ24uiIbImKl18pSd91m0rkGMq"></div></div>'
+    doc = filter(input)
+
+    expect(doc.to_s).to eq output
+  end
+
+  it 'should not replace plantuml pre tag with img tag if disabled' do
+    stub_application_setting(plantuml_enabled: false)
+    input = '<pre class="plantuml"><code>Bob -> Sara : Hello</code><pre>'
+    output = '<pre class="plantuml"><code>Bob -&gt; Sara : Hello</code><pre></pre></pre>'
+    doc = filter(input)
+
+    expect(doc.to_s).to eq output
+  end
+
+  it 'should not replace plantuml pre tag with img tag if url is invalid' do
+    stub_application_setting(plantuml_enabled: true, plantuml_url: "invalid")
+    input = '<pre class="plantuml"><code>Bob -> Sara : Hello</code><pre>'
+    output = '<div class="listingblock"><div class="content"><pre class="plantuml plantuml-error"> PlantUML Error: cannot connect to PlantUML server at "invalid"</pre></div></div>'
+    doc = filter(input)
+
+    expect(doc.to_s).to eq output
+  end
+end