ensure to_h doesnt cause things to explode

lib/jekyll-seo-tag/drop.rb

@@ -2,8 +2,12 @@ module Jekyll
   class SeoTag
     class Drop < Jekyll::Drops::Drop
       TITLE_SEPARATOR = " | ".freeze
-      include Jekyll::Filters
-      include Liquid::StandardFilters
+      INCLUDES = [Jekyll::Filters, Liquid::StandardFilters].freeze
+
+      INCLUDES.each do |klass|
+        include klass
+        klass.instance_methods.each { |method| private method }
+      end
 
       def initialize(text, context)
         @obj = {}
@@ -190,7 +194,7 @@ module Jekyll
       def format_string(string)
         methods = %i[markdownify strip_html normalize_whitespace escape_once]
         methods.each do |method|
-          string = public_send(method, string)
+          string = send(method, string)
         end
 
         string unless string.empty?

spec/jekyll_seo_tag/drop_spec.rb

@@ -7,6 +7,14 @@ RSpec.describe Jekyll::SeoTag::Drop do
   let(:text) { "" }
   subject { described_class.new(text, context) }
 
+  # Drop includes liquid filters which expect arguments
+  # By default, in drops, `to_h` will call each public method with no arugments
+  # Here, that would cause the filters to explode. This test ensures that all
+  # public methods don't explode when called without arguments. Don't explode.
+  it "doesn't blow up on to_h" do
+    expect { subject.to_h }.to_not raise_error
+  end
+
   it "returns the version" do
     expect(subject.version).to eql(Jekyll::SeoTag::VERSION)
   end