tests: switch to minitest

Ruby 1.9+ uses Minitest as the backend for Test::Unit. As of Minitest 5,
the shim has broken some compatibility with Test::Unit::TestCase in some
scenarios.

Adjusts the test suite to support Minitest 5's syntax.

Minitest versions 4 and below do not support the newer Minitest::Test
class that arrived in version 5. For that case, use the
MiniTest::Unit::TestCase class as a fallback

Conflicts:
	test/integration/tags/for_tag_test.rb
	test/test_helper.rb

test/integration/parsing_quirks_test.rb

@@ -1,6 +1,6 @@
 require 'test_helper'
 
-class ParsingQuirksTest < Test::Unit::TestCase
+class ParsingQuirksTest < Minitest::Test
   include Liquid
 
   def test_parsing_css
@@ -9,30 +9,28 @@ class ParsingQuirksTest < Test::Unit::TestCase
   end
 
   def test_raise_on_single_close_bracet
-    assert_raise(SyntaxError) do
+    assert_raises(SyntaxError) do
       Template.parse("text {{method} oh nos!")
     end
   end
 
   def test_raise_on_label_and_no_close_bracets
-    assert_raise(SyntaxError) do
+    assert_raises(SyntaxError) do
       Template.parse("TEST {{ ")
     end
   end
 
   def test_raise_on_label_and_no_close_bracets_percent
-    assert_raise(SyntaxError) do
+    assert_raises(SyntaxError) do
       Template.parse("TEST {% ")
     end
   end
 
   def test_error_on_empty_filter
-    assert_nothing_raised do
-      Template.parse("{{test}}")
-      Template.parse("{{|test}}")
-    end
+    assert Template.parse("{{test}}")
+    assert Template.parse("{{|test}}")
     with_error_mode(:strict) do
-      assert_raise(SyntaxError) do
+      assert_raises(SyntaxError) do
         Template.parse("{{test |a|b|}}")
       end
     end
@@ -40,7 +38,7 @@ class ParsingQuirksTest < Test::Unit::TestCase
 
   def test_meaningless_parens_error
     with_error_mode(:strict) do
-      assert_raise(SyntaxError) do
+      assert_raises(SyntaxError) do
         markup = "a == 'foo' or (b == 'bar' and c == 'baz') or false"
         Template.parse("{% if #{markup} %} YES {% endif %}")
       end
@@ -49,11 +47,11 @@ class ParsingQuirksTest < Test::Unit::TestCase
 
   def test_unexpected_characters_syntax_error
     with_error_mode(:strict) do
-      assert_raise(SyntaxError) do
+      assert_raises(SyntaxError) do
         markup = "true && false"
         Template.parse("{% if #{markup} %} YES {% endif %}")
       end
-      assert_raise(SyntaxError) do
+      assert_raises(SyntaxError) do
         markup = "false || true"
         Template.parse("{% if #{markup} %} YES {% endif %}")
       end
@@ -61,11 +59,9 @@ class ParsingQuirksTest < Test::Unit::TestCase
   end
 
   def test_no_error_on_lax_empty_filter
-    assert_nothing_raised do
-      Template.parse("{{test |a|b|}}", :error_mode => :lax)
-      Template.parse("{{test}}", :error_mode => :lax)
-      Template.parse("{{|test|}}", :error_mode => :lax)
-    end
+    assert Template.parse("{{test |a|b|}}", :error_mode => :lax)
+    assert Template.parse("{{test}}", :error_mode => :lax)
+    assert Template.parse("{{|test|}}", :error_mode => :lax)
   end
 
   def test_meaningless_parens_lax