From d8f31046a9d39651909ec98a70249b7fe8f05461 Mon Sep 17 00:00:00 2001
From: Martin Morissette <martin.morissette@shopify.com>
Date: Sun, 15 Dec 2019 14:59:09 -0500
Subject: [PATCH] Introduce template factory

---
 lib/liquid.rb                           |  1 +
 lib/liquid/partial_cache.rb             |  5 +++-
 lib/liquid/template_factory.rb          |  9 +++++++
 test/test_helper.rb                     | 13 +++++++++
 test/unit/partial_cache_unit_test.rb    | 35 +++++++++++++++++++++++++
 test/unit/template_factory_unit_test.rb | 12 +++++++++
 6 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 lib/liquid/template_factory.rb
 create mode 100644 test/unit/template_factory_unit_test.rb

diff --git a/lib/liquid.rb b/lib/liquid.rb
index cfaccee..733fd82 100644
--- a/lib/liquid.rb
+++ b/lib/liquid.rb
@@ -80,6 +80,7 @@ require 'liquid/partial_cache'
 require 'liquid/usage'
 require 'liquid/register'
 require 'liquid/static_registers'
+require 'liquid/template_factory'
 
 # Load all the tags of the standard library
 #
diff --git a/lib/liquid/partial_cache.rb b/lib/liquid/partial_cache.rb
index 8c2e5d2..856d307 100644
--- a/lib/liquid/partial_cache.rb
+++ b/lib/liquid/partial_cache.rb
@@ -12,7 +12,10 @@ module Liquid
 
       parse_context.partial = true
 
-      partial = Liquid::Template.parse(source, parse_context)
+      template_factory = (context.registers[:template_factory] ||= Liquid::TemplateFactory.new)
+      template = template_factory.for(template_name)
+
+      partial = template.parse(source, parse_context)
       cached_partials[template_name] = partial
     ensure
       parse_context.partial = false
diff --git a/lib/liquid/template_factory.rb b/lib/liquid/template_factory.rb
new file mode 100644
index 0000000..f6031c9
--- /dev/null
+++ b/lib/liquid/template_factory.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module Liquid
+  class TemplateFactory
+    def for(_template_name)
+      Liquid::Template.new
+    end
+  end
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 7422129..7356a29 100755
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -136,3 +136,16 @@ class StubFileSystem
     @values.fetch(template_path)
   end
 end
+
+class StubTemplateFactory
+  attr_reader :count
+
+  def initialize
+    @count = 0
+  end
+
+  def for(_template_name)
+    @count += 1
+    Liquid::Template.new
+  end
+end
diff --git a/test/unit/partial_cache_unit_test.rb b/test/unit/partial_cache_unit_test.rb
index 2f6218a..27912c0 100644
--- a/test/unit/partial_cache_unit_test.rb
+++ b/test/unit/partial_cache_unit_test.rb
@@ -90,4 +90,39 @@ class PartialCacheUnitTest < Minitest::Test
     # but measuring file reads is an OK proxy for this.
     assert_equal(1, file_system.file_read_count)
   end
+
+  def test_uses_default_template_factory_when_no_template_factory_found_in_register
+    context = Liquid::Context.build(
+      registers: {
+        file_system: StubFileSystem.new('my_partial' => 'my partial body'),
+      }
+    )
+
+    partial = Liquid::PartialCache.load(
+      'my_partial',
+      context: context,
+      parse_context: Liquid::ParseContext.new
+    )
+
+    assert_equal('my partial body', partial.render)
+  end
+
+  def test_uses_template_factory_register_if_present
+    template_factory = StubTemplateFactory.new
+    context = Liquid::Context.build(
+      registers: {
+        file_system: StubFileSystem.new('my_partial' => 'my partial body'),
+        template_factory: template_factory,
+      }
+    )
+
+    partial = Liquid::PartialCache.load(
+      'my_partial',
+      context: context,
+      parse_context: Liquid::ParseContext.new
+    )
+
+    assert_equal('my partial body', partial.render)
+    assert_equal(1, template_factory.count)
+  end
 end
diff --git a/test/unit/template_factory_unit_test.rb b/test/unit/template_factory_unit_test.rb
new file mode 100644
index 0000000..d492505
--- /dev/null
+++ b/test/unit/template_factory_unit_test.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class TemplateFactoryUnitTest < Minitest::Test
+  include Liquid
+
+  def test_for_returns_liquid_template_instance
+    template = TemplateFactory.new.for("anything")
+    assert_instance_of(Liquid::Template, template)
+  end
+end