```ruby
require "test_helper"
require "shrine/plugins/dynamic_storage"

describe Shrine::Plugins::DynamicStorage do
  before do
    @uploader = uploader { plugin :dynamic_storage }
  end

  it "allows registering a storage with a regex" do
    @uploader.class.storage /store_(\w+)/ do |match|
      match[1].to_sym
    end

    assert_equal :foo, @uploader.class.new(:store_foo).storage
    assert_equal :bar, @uploader.class.new(:store_bar).storage
  end

  it "delegates to default behaviour when storage wasn't found" do
    assert_instance_of Shrine::Storage::Memory, @uploader.class.new(:store).storage
  end
end
```

Replace last occurrence of Shrine::Storage::Memory
user
```ruby
require "test_helper"
require "shrine/plugins/dynamic_storage"

describe Shrine::Plugins::DynamicStorage do
  before do
    @uploader = uploader { plugin :dynamic_storage }
  end

  it "allows registering a storage with a regex" do
    @uploader.class.storage /store_(\w+)/ do |match|
      match[1].to_sym
    end

    assert_equal :foo, @uploader.class.new(:store_foo).storage
    assert_equal :bar, @uploader.class.new(:store_bar).storage
  end

  it "delegates to default behaviour when storage wasn't found" do
    assert_instance_of Shrine::Storage::Test, @uploader.class.new(:store).storage
  end
end
```
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