```ruby
require 'test_helper'
require 'html/pipeline/gitlab'

class HTML::Pipeline::GitLabEmojiFilterTest < Minitest::Test
  GitLabEmojiFilter = HTML::Pipeline::GitLab::GitLabEmojiFilter
  
  def test_emojify
    filter = GitLabEmojiFilter.new('<p>:heart:</p>', {:asset_root: 'https://foo.com'})
    doc = filter.call
    assert_match 'https://foo.com/emoji/heart.png', doc.search('img').attr('src').value
  end

  def test_unsupported_emoji
    block = '<p>:sheep:</p>'
    filter = GitLabEmojiFilter.new(block, {:asset_root: 'https://foo.com'})
    doc = filter.call
    assert_match block, doc.to_html
  end
  
  def test_uri_encoding
    filter = GitLabEmojiFilter.new('<p>:+1:</p>', {:asset_root: 'https://foo.com'})
    doc = filter.call
    assert_match 'https://foo.com/emoji/%2B1.png', doc.search('img').attr('src').value
  end
  
  def test_required_context_validation
    exception = assert_raises(ArgumentError) { 
      GitLabEmojiFilter.call("", {}) 
    }
    assert_match /:asset_root/, exception.message
  end
end
```

Use ruby 1.9 hash syntax
user
```ruby
require 'test_helper'
require 'html/pipeline/gitlab'

class HTML::Pipeline::GitLabEmojiFilterTest < Minitest::Test
  GitLabEmojiFilter = HTML::Pipeline::GitLab::GitLabEmojiFilter
  
  def test_emojify
    filter = GitLabEmojiFilter.new('<p>:heart:</p>', {asset_root: 'https://foo.com'})
    doc = filter.call
    assert_match 'https://foo.com/emoji/heart.png', doc.search('img').attr('src').value
  end

  def test_unsupported_emoji
    block = '<p>:sheep:</p>'
    filter = GitLabEmojiFilter.new(block, {asset_root: 'https://foo.com'})
    doc = filter.call
    assert_match block, doc.to_html
  end
  
  def test_uri_encoding
    filter = GitLabEmojiFilter.new('<p>:+1:</p>', {asset_root: 'https://foo.com'})
    doc = filter.call
    assert_match 'https://foo.com/emoji/%2B1.png', doc.search('img').attr('src').value
  end
  
  def test_required_context_validation
    exception = assert_raises(ArgumentError) { 
      GitLabEmojiFilter.call("", {}) 
    }
    assert_match /:asset_root/, exception.message
  end
end
```
assistant