Add end tag support (Shopify#1823)

Author: charlespwd

lib/liquid/block.rb

@@ -34,15 +34,15 @@ def unknown_tag(tag_name, _markup, _tokenizer)
     end
 
     # @api private
-    def self.raise_unknown_tag(tag, block_name, block_delimiter, parse_context)
+    def self.raise_unknown_tag(tag, block_name, block_delimiter, parse_context, supports_end_tag = true)
       if tag == 'else'
         raise SyntaxError, parse_context.locale.t(
           "errors.syntax.unexpected_else",
           block_name: block_name,
         )
       elsif tag.start_with?('end')
         raise SyntaxError, parse_context.locale.t(
-          "errors.syntax.invalid_delimiter",
+          supports_end_tag ? "errors.syntax.invalid_delimiter" : "errors.syntax.invalid_delimiter_no_end",
           tag: tag,
           block_name: block_name,
           block_delimiter: block_delimiter,
@@ -64,6 +64,10 @@ def block_delimiter
       @block_delimiter ||= "end#{block_name}"
     end
 
+    def supports_end_tag?
+      true
+    end
+
     private
 
     # @api public
@@ -81,7 +85,7 @@ def parse_body(body, tokens)
         body.parse(tokens, parse_context) do |end_tag_name, end_tag_params|
           @blank &&= body.blank?
 
-          return false if end_tag_name == block_delimiter
+          return false if end_tag_name == block_delimiter || (supports_end_tag? && end_tag_name == 'end')
           raise_tag_never_closed(block_name) unless end_tag_name
 
           # this tag is not registered with the system

lib/liquid/block_body.rb

@@ -68,7 +68,7 @@ def freeze
 
     # @api private
     def self.unknown_tag_in_liquid_tag(tag, parse_context)
-      Block.raise_unknown_tag(tag, 'liquid', '%}', parse_context)
+      Block.raise_unknown_tag(tag, 'liquid', '%}', parse_context, false)
     end
 
     # @api private

lib/liquid/locales/en.yml

@@ -14,7 +14,8 @@
       if: "Syntax Error in tag 'if' - Valid syntax: if [expression]"
       include: "Error in tag 'include' - Valid syntax: include '[template]' (with|for) [object|collection]"
       inline_comment_invalid: "Syntax error in tag '#' - Each line of comments must be prefixed by the '#' character"
-      invalid_delimiter: "'%{tag}' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
+      invalid_delimiter: "'%{tag}' is not a valid delimiter for %{block_name} tags. use end or %{block_delimiter}"
+      invalid_delimiter_no_end: "'%{tag}' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
       render: "Syntax error in tag 'render' - Template name must be a quoted string"
       table_row: "Syntax Error in 'table_row loop' - Valid syntax: table_row [item] in [collection] cols=3"
       tag_never_closed: "'%{block_name}' tag was never closed"

lib/liquid/tags/comment.rb

@@ -22,6 +22,10 @@ def render_to_output_buffer(_context, output)
     def unknown_tag(_tag, _markup, _tokens)
     end
 
+    def supports_end_tag?
+      false
+    end
+
     def blank?
       true
     end

lib/liquid/tags/raw.rb

@@ -22,6 +22,10 @@ def initialize(tag_name, markup, parse_context)
       ensure_valid_markup(tag_name, markup, parse_context)
     end
 
+    def supports_end_tag?
+      false
+    end
+
     def parse(tokens)
       @body = +''
       while (token = tokens.shift)

test/integration/block_test.rb

@@ -5,9 +5,31 @@
 class BlockTest < Minitest::Test
   include Liquid
 
+  def test_simple_end_tag
+    assert_template_result('you rock', '{% if true %}you rock{% end %}')
+    assert_template_result('you rock', '{% if true %}{% unless false %}you rock{% end %}{% end %}')
+  end
+
   def test_unexpected_end_tag
     source = '{% if true %}{% endunless %}'
-    assert_match_syntax_error("Liquid syntax error (line 1): 'endunless' is not a valid delimiter for if tags. use endif", source)
+    assert_match_syntax_error("Liquid syntax error (line 1): 'endunless' is not a valid delimiter for if tags. use end or endif", source)
+  end
+
+  def test_end_closes_closest_open_tag
+    source = '{% if true %}{% unless true %}{% end %}{% endunless %}'
+    assert_match_syntax_error("Liquid syntax error (line 1): 'endunless' is not a valid delimiter for if tags. use end or endif", source)
+  end
+
+  # comments are special and can't be closed by `end`
+  def test_unexpected_end_tag_comment
+    source = '{% comment %}{% end %}'
+    assert_match_syntax_error("Liquid syntax error (line 1): 'comment' tag was never closed", source)
+  end
+
+  # raw is special and can't be closed by `end`
+  def test_unexpected_end_tag_raw
+    source = '{% raw %}{% end %}'
+    assert_match_syntax_error("Liquid syntax error (line 1): 'raw' tag was never closed", source)
   end
 
   def test_with_custom_tag

test/integration/tags/if_else_tag_test.rb

@@ -12,6 +12,7 @@ def test_if
       ' {% if true %} this text should go into the output {% endif %} ',
     )
     assert_template_result('  you rock ?', '{% if false %} you suck {% endif %} {% if true %} you rock {% endif %}?')
+    assert_template_result('  you rock ?', '{% if false %} you suck {% endif %} {% if true %} you rock {% end %}?')
   end
 
   def test_literal_comparisons

test/integration/tags/liquid_tag_test.rb

@@ -106,6 +106,11 @@ def test_cannot_close_blocks_created_before_a_liquid_tag
       42
       {%- liquid endif -%}
     LIQUID
+    assert_match_syntax_error("syntax error (line 3): 'end' is not a valid delimiter for liquid tags. use %}", <<~LIQUID)
+      {%- if true -%}
+      42
+      {%- liquid end -%}
+    LIQUID
   end
 
   def test_liquid_tag_in_raw
@@ -123,6 +128,15 @@ def test_nested_liquid_tags
           endif
       -%}
     LIQUID
+
+    assert_template_result('good', <<~LIQUID)
+      {%- liquid
+        liquid
+          if true
+            echo "good"
+          end
+      -%}
+    LIQUID
   end
 
   def test_nested_liquid_tags_on_same_line

test/integration/tags/raw_tag_test.rb

@@ -10,6 +10,10 @@ def test_tag_in_raw
       '{% comment %} test {% endcomment %}',
       '{% raw %}{% comment %} test {% endcomment %}{% endraw %}',
     )
+    assert_template_result(
+      '',
+      '{% comment %} {% if true %}{% end %} {% endcomment %}',
+    )
   end
 
   def test_output_in_raw

test/integration/tags/standard_tag_test.rb

@@ -38,6 +38,7 @@ def test_has_a_block_which_does_nothing
     assert_template_result('', '{%comment%}{%blabla%}{%endcomment%}')
     assert_template_result('', '{% comment %}{% blabla %}{% endcomment %}')
     assert_template_result('', '{%comment%}{% endif %}{%endcomment%}')
+    assert_template_result('', '{%comment%}{% end %}{%endcomment%}')
     assert_template_result('', '{% comment %}{% endwhatever %}{% endcomment %}')
     assert_template_result('', '{% comment %}{% raw %} {{%%%%}}  }} { {% endcomment %} {% comment {% endraw %} {% endcomment %}')
     assert_template_result('', '{% comment %}{% " %}{% endcomment %}')