Fix echo tag

lib/liquid/block.rb

@@ -7,6 +7,7 @@ module Liquid
     def initialize(tag_name, markup, options)
       super
       @blank = true
+      @body = nil
     end
 
     def parse(tokens)
@@ -17,7 +18,7 @@ module Liquid
 
     # For backwards compatibility
     def render(context)
-      @body.render(context)
+      @body&.render(context)
     end
 
     def blank?

lib/liquid/tag.rb

@@ -2,7 +2,7 @@
 
 module Liquid
   class Tag
-    attr_reader :nodelist, :tag_name, :line_number, :parse_context
+    attr_reader :nodelist, :tag_name, :line_number, :parse_context, :markup
     alias_method :options, :parse_context
     include ParserSwitching
 
@@ -17,8 +17,6 @@ module Liquid
         disabled_tags.push(*tags)
       end
 
-      private :new
-
       def disabled_tags
         @disabled_tags ||= []
       end

lib/liquid/tags/assign.rb

@@ -18,8 +18,7 @@ module Liquid
 
     attr_reader :to, :from
 
-    def initialize(tag_name, markup, options)
-      super
+    def parse(_tokens)
       if markup =~ Syntax
         @to = Regexp.last_match(1)
         @from = Variable.new(Regexp.last_match(2), options)

lib/liquid/tags/capture.rb

@@ -15,13 +15,13 @@ module Liquid
   class Capture < Block
     Syntax = /(#{VariableSignature}+)/o
 
-    def initialize(tag_name, markup, options)
-      super
+    def parse(_tokens)
       if markup =~ Syntax
         @to = Regexp.last_match(1)
       else
         raise SyntaxError, options[:locale].t("errors.syntax.capture")
       end
+      super
     end
 
     def render_to_output_buffer(context, output)

lib/liquid/tags/case.rb

@@ -7,8 +7,7 @@ module Liquid
 
     attr_reader :blocks, :left
 
-    def initialize(tag_name, markup, options)
-      super
+    def parse(tokens)
       @blocks = []
 
       if markup =~ Syntax
@@ -16,9 +15,7 @@ module Liquid
       else
         raise SyntaxError, options[:locale].t("errors.syntax.case")
       end
-    end
 
-    def parse(tokens)
       body = BlockBody.new
       body = @blocks.last.attachment while parse_body(body, tokens)
     end

lib/liquid/tags/cycle.rb

@@ -19,8 +19,7 @@ module Liquid
 
     attr_reader :variables
 
-    def initialize(tag_name, markup, options)
-      super
+    def parse(_tokens)
       case markup
       when NamedSyntax
         @variables = variables_from_string(Regexp.last_match(2))

lib/liquid/tags/decrement.rb

@@ -20,8 +20,7 @@ module Liquid
   #    Hello: -3
   #
   class Decrement < Tag
-    def initialize(tag_name, markup, options)
-      super
+    def parse(_tokens)
       @variable = markup.strip
     end
 

lib/liquid/tags/echo.rb

@@ -12,13 +12,14 @@ module Liquid
   #   {% echo user | link %}
   #
   class Echo < Tag
-    def initialize(tag_name, markup, parse_context)
-      super
+    attr_reader :variable
+
+    def parse(_tokens)
       @variable = Variable.new(markup, parse_context)
     end
 
     def render(context)
-      @variable.render_to_output_buffer(context, +'')
+      variable&.render_to_output_buffer(context, +'')
     end
   end
 

lib/liquid/tags/for.rb

@@ -50,15 +50,11 @@ module Liquid
 
     attr_reader :collection_name, :variable_name, :limit, :from
 
-    def initialize(tag_name, markup, options)
-      super
+    def parse(tokens)
       @from = @limit = nil
       parse_with_selected_parser(markup)
       @for_block = BlockBody.new
       @else_block = nil
-    end
-
-    def parse(tokens)
       return unless parse_body(@for_block, tokens)
       parse_body(@else_block, tokens)
     end

lib/liquid/tags/if.rb

@@ -18,17 +18,13 @@ module Liquid
 
     attr_reader :blocks
 
-    def initialize(tag_name, markup, options)
-      super
-      @blocks = []
-      push_block('if', markup)
-    end
-
     def nodelist
       @blocks.map(&:attachment)
     end
 
     def parse(tokens)
+      @blocks = []
+      push_block('if', markup)
       while parse_body(@blocks.last.attachment, tokens)
       end
     end

lib/liquid/tags/include.rb

@@ -21,9 +21,7 @@ module Liquid
 
     attr_reader :template_name_expr, :variable_name_expr, :attributes
 
-    def initialize(tag_name, markup, options)
-      super
-
+    def parse(_tokens)
       if markup =~ SYNTAX
 
         template_name = Regexp.last_match(1)
@@ -43,9 +41,6 @@ module Liquid
       end
     end
 
-    def parse(_tokens)
-    end
-
     def render_to_output_buffer(context, output)
       template_name = context.evaluate(@template_name_expr)
       raise ArgumentError, options[:locale].t("errors.argument.include") unless template_name

lib/liquid/tags/increment.rb

@@ -17,8 +17,7 @@ module Liquid
   #    Hello: 2
   #
   class Increment < Tag
-    def initialize(tag_name, markup, options)
-      super
+    def parse(_tokens)
       @variable = markup.strip
     end
 

lib/liquid/tags/raw.rb

@@ -5,13 +5,8 @@ module Liquid
     Syntax = /\A\s*\z/
     FullTokenPossiblyInvalid = /\A(.*)#{TagStart}\s*(\w+)\s*(.*)?#{TagEnd}\z/om
 
-    def initialize(tag_name, markup, parse_context)
-      super
-
-      ensure_valid_markup(tag_name, markup, parse_context)
-    end
-
     def parse(tokens)
+      ensure_valid_markup(tag_name, markup, parse_context)
       @body = +''
       while (token = tokens.shift)
         if token =~ FullTokenPossiblyInvalid

lib/liquid/tags/render.rb

@@ -8,9 +8,7 @@ module Liquid
 
     attr_reader :template_name_expr, :attributes
 
-    def initialize(tag_name, markup, options)
-      super
-
+    def parse(_tokens)
       raise SyntaxError, options[:locale].t("errors.syntax.render") unless markup =~ SYNTAX
 
       template_name = Regexp.last_match(1)

lib/liquid/tags/table_row.rb

@@ -6,8 +6,7 @@ module Liquid
 
     attr_reader :variable_name, :collection_name, :attributes
 
-    def initialize(tag_name, markup, options)
-      super
+    def parse(_tokens)
       if markup =~ Syntax
         @variable_name = Regexp.last_match(1)
         @collection_name = Expression.parse(Regexp.last_match(2))
@@ -18,6 +17,7 @@ module Liquid
       else
         raise SyntaxError, options[:locale].t("errors.syntax.table_row")
       end
+      super
     end
 
     def render_to_output_buffer(context, output)

test/integration/tag_test.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class TagTest < Minitest::Test
+  include Liquid
+
+  def test_all_tags_with_no_parse_can_render
+    Template.tags.each do |key, _tag|
+      Template.tags[key].new(key, '', ParseContext.new).render(Context.new)
+      assert_nil(nil)
+    end
+  end
+
+  def test_all_tags_are_registered
+    tags = Template.tags.map { |key, _tag| key }
+    expected_tags = %w(assign break capture case comment continue cycle decrement echo for if ifchanged include increment raw render tablerow unless)
+    assert_equal(expected_tags, tags.sort)
+  end
+end