Fix bug in `WikiLinkFilter`.

1. An exception would be raised if the filter was called with an invalid
   URI. Mainly because we weren't catching the `Addressable` exception.

2. This commit fixes it and adds a spec for the filter.

lib/banzai/filter/wiki_link_filter.rb

@@ -29,7 +29,7 @@ module Banzai
         return if html_attr.blank?
 
         html_attr.value = apply_rewrite_rules(html_attr.value)
-      rescue URI::Error
+      rescue URI::Error, Addressable::URI::InvalidURIError
         # noop
       end
 

spec/lib/banzai/filter/wiki_link_filter_spec.rb

+require 'spec_helper'
+
+describe Banzai::Filter::WikiLinkFilter, lib: true do
+  include FilterSpecHelper
+
+  let(:namespace) { build_stubbed(:namespace, name: "wiki_link_ns") }
+  let(:project)   { build_stubbed(:empty_project, :public, name: "wiki_link_project", namespace: namespace) }
+  let(:user) { double }
+  let(:wiki) { ProjectWiki.new(project, user) }
+
+  it "doesn't rewrite absolute links" do
+    filtered_link = filter("<a href='http://example.com:8000/'>Link</a>", project_wiki: wiki).children[0]
+    expect(filtered_link.attribute('href').value).to eq('http://example.com:8000/')
+  end
+
+  describe "invalid links" do
+    invalid_links = ["http://:8080", "http://", "http://:8080/path"]
+
+    invalid_links.each do |invalid_link|
+      it "doesn't rewrite invalid invalid_links like #{invalid_link}" do
+        filtered_link = filter("<a href='#{invalid_link}'>Link</a>", project_wiki: wiki).children[0]
+        expect(filtered_link.attribute('href').value).to eq(invalid_link)
+      end
+    end
+  end
+end