Fix liquid tag nested in outer block

.rubocop_todo.yml

@@ -21,6 +21,10 @@ Lint/InheritException:
 Layout/LineLength:
   Max: 294
 
+# Offense count: 1
+Metrics/BlockNesting:
+  Max: 4
+
 # Offense count: 44
 Naming/ConstantName:
   Exclude:

lib/liquid/block_body.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'English'
+
 module Liquid
   class BlockBody
     LiquidTagToken      = /\A\s*(\w+)\s*(.*?)\z/o
@@ -51,6 +53,13 @@ module Liquid
       yield nil, nil
     end
 
+    # @api private
+    def self.unknown_tag_in_liquid_tag(end_tag_name, end_tag_markup)
+      yield end_tag_name, end_tag_markup
+    ensure
+      Usage.increment("liquid_tag_contains_outer_tag") unless $ERROR_INFO.is_a?(SyntaxError)
+    end
+
     private def parse_for_document(tokenizer, parse_context, &block)
       while (token = tokenizer.shift)
         next if token.empty?
@@ -71,7 +80,11 @@ module Liquid
 
           if tag_name == 'liquid'
             liquid_tag_tokenizer = Tokenizer.new(markup, line_number: parse_context.line_number, for_liquid_tag: true)
-            next parse_for_liquid_tag(liquid_tag_tokenizer, parse_context, &block)
+            parse_for_liquid_tag(liquid_tag_tokenizer, parse_context) do |end_tag_name, end_tag_markup|
+              next unless end_tag_name
+              self.class.unknown_tag_in_liquid_tag(end_tag_name, end_tag_markup, &block)
+            end
+            next
           end
 
           unless (tag = registered_tags[tag_name])

test/integration/tags/liquid_tag_test.rb

@@ -81,6 +81,18 @@ class LiquidTagTest < Minitest::Test
     assert_match_syntax_error("syntax error (line 3): Unknown tag 'error'", "{% liquid echo ''\n  \n error %}")
   end
 
+  def test_nested_liquid_tag
+    assert_usage_increment("liquid_tag_contains_outer_tag", times: 0) do
+      assert_template_result('good', <<~LIQUID)
+        {%- if true %}
+          {%- liquid
+            echo "good"
+          %}
+        {%- endif -%}
+      LIQUID
+    end
+  end
+
   def test_cannot_open_blocks_living_past_a_liquid_tag
     assert_match_syntax_error("syntax error (line 3): 'if' tag was never closed", <<~LIQUID)
       {%- liquid
@@ -91,11 +103,13 @@ class LiquidTagTest < Minitest::Test
   end
 
   def test_quirk_can_close_blocks_created_before_a_liquid_tag
-    assert_template_result("42", <<~LIQUID)
-      {%- if true -%}
-      42
-      {%- liquid endif -%}
-    LIQUID
+    assert_usage_increment("liquid_tag_contains_outer_tag") do
+      assert_template_result("42", <<~LIQUID)
+        {%- if true -%}
+        42
+        {%- liquid endif -%}
+      LIQUID
+    end
   end
 
   def test_liquid_tag_in_raw

test/test_helper.rb

@@ -58,6 +58,23 @@ module Minitest
       assert_match(match, exception.message)
     end
 
+    def assert_usage_increment(name, times: 1)
+      old_method = Liquid::Usage.method(:increment)
+      calls = 0
+      begin
+        Liquid::Usage.singleton_class.send(:remove_method, :increment)
+        Liquid::Usage.define_singleton_method(:increment) do |got_name|
+          calls += 1 if got_name == name
+          old_method.call(got_name)
+        end
+        yield
+      ensure
+        Liquid::Usage.singleton_class.send(:remove_method, :increment)
+        Liquid::Usage.define_singleton_method(:increment, old_method)
+      end
+      assert_equal(times, calls, "Number of calls to Usage.increment with #{name.inspect}")
+    end
+
     def with_global_filter(*globals)
       original_global_filters = Liquid::StrainerFactory.instance_variable_get(:@global_filters)
       Liquid::StrainerFactory.instance_variable_set(:@global_filters, [])