Introduce new inline snippets tag

Inline snippets will reduce code duplication and
improve the developer experience, eliminating the
need for one-off snippet files

test/integration/tags/snippet_test.rb

@@ -0,0 +1,190 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class SnippetTest < Minitest::Test
+  include Liquid
+
+  def test_valid_inline_snippet
+    template = <<~LIQUID.strip
+      {% snippet "input" %}
+        Hey
+      {% endsnippet %}
+    LIQUID
+    expected = ''
+
+    assert_template_result(expected, template)
+  end
+
+  def test_invalid_inline_snippet
+    template = <<~LIQUID.strip
+      {% snippet input %}
+        Hey
+      {% endsnippet %}
+    LIQUID
+    expected = "Syntax Error in 'snippet' - Valid syntax: snippet [quoted string]"
+
+    assert_match_syntax_error(expected, template)
+  end
+
+  def test_render_inline_snippet
+    template = <<~LIQUID.strip
+      {% snippet "hey" %}
+      Hey
+      {% endsnippet %}
+
+      {%- render "hey" -%}
+    LIQUID
+    expected = <<~OUTPUT
+
+      Hey
+    OUTPUT
+
+    assert_template_result(expected, template)
+  end
+
+  def test_render_multiple_inline_snippets
+    template = <<~LIQUID.strip
+      {% snippet "input" %}
+      <input />
+      {% endsnippet %}
+
+      {% snippet "banner" %}
+      <marquee direction="up" height="100px">
+        Welcome to my store!
+      </marquee>
+      {% endsnippet %}
+
+      {%- render "input" -%}
+      {%- render "banner" -%}
+    LIQUID
+    expected = <<~OUTPUT
+
+
+
+      <input />
+
+      <marquee direction="up" height="100px">
+        Welcome to my store!
+      </marquee>
+    OUTPUT
+
+    assert_template_result(expected, template)
+  end
+
+  def test_render_inline_snippet_with_argument
+    template = <<~LIQUID.strip
+      {% snippet "input" |type| %}
+      <input type="{{ type }}" />
+      {% endsnippet %}
+
+      {%- render "input", type: "text" -%}
+    LIQUID
+    expected = <<~OUTPUT
+
+      <input type="text" />
+    OUTPUT
+
+    assert_template_result(expected, template)
+  end
+
+  def test_render_inline_snippet_with_multiple_arguments
+    template = <<~LIQUID.strip
+      {% snippet "input" |type, value| %}
+      <input type="{{ type }}" value="{{ value }}" />
+      {% endsnippet %}
+
+      {%- render "input", type: "text", value: "Hello" -%}
+    LIQUID
+    expected = <<~OUTPUT
+
+      <input type="text" value="Hello" />
+    OUTPUT
+
+    assert_template_result(expected, template)
+  end
+
+  def test_render_inline_snippets_using_same_argument_name
+    template = <<~LIQUID.strip
+      {% snippet "input" |type| %}
+      <input type="{{ type }}" />
+      {% endsnippet %}
+
+      {% snippet "inputs" |type, value| %}
+        <input type="{{ type }}" value="{{ value }}" />
+      {% endsnippet %}
+
+      {%- render "input", type: "text" -%}
+      {%- render "inputs", type: "password", value: "pass" -%}
+    LIQUID
+    expected = <<~OUTPUT
+
+
+
+      <input type="text" />
+
+        <input type="password" value="pass" />
+    OUTPUT
+
+    assert_template_result(expected, template)
+  end
+
+  def test_render_inline_snippet_empty_string_when_missing_argument
+    template = <<~LIQUID.strip
+      {% snippet "input" |type| %}
+      <input type="{{ type }}" value="{{ value }}" />
+      {% endsnippet %}
+
+      {%- render "input", type: "text" -%}
+    LIQUID
+    expected = <<~OUTPUT
+
+      <input type="text" value="" />
+    OUTPUT
+
+    assert_template_result(expected, template)
+  end
+
+  def test_render_inline_snippet_shouldnt_leak_context
+    template = <<~LIQUID.strip
+      {% snippet "input" |type, value| %}
+      <input type="{{ type }}" value="{{ value }}" />
+      {% endsnippet %}
+
+      {%- render "input", type: "text", value: "Hello" -%}
+
+      {{ type }}
+      {{ value }}
+    LIQUID
+    expected = <<~OUTPUT
+
+      <input type="text" value="Hello" />
+
+    OUTPUT
+
+    assert_template_result(expected, template)
+  end
+
+  def test_render_multiple_inline_snippets_without_leaking_context
+    template = <<~LIQUID.strip
+      {% snippet "input" |type| %}
+      <input type="{{ type }}" />
+      {% endsnippet %}
+      {% snippet "no_leak" %}
+      <input type="{{ type }}" />
+      {% endsnippet %}
+
+      {%- render "input", type: "text" -%}
+      {%- render "no_leak" -%}
+    LIQUID
+    expected = <<~OUTPUT
+
+
+      <input type="text" />
+
+      <input type="" />
+    OUTPUT
+
+    assert_template_result(expected, template)
+  end
+end