```ruby
require 'test_helper'

class ConfigTest < Test::Unit::TestCase
  def test_set_ssl_cert_file
    @config = PaypalAdaptive::Config.new("test", { "ssl_cert_file" => "/path/to/cacert.pem" })
    assert_equal "/path/to/cacert.pem", @config.ssl_cert_file
    assert_equal nil, @config.ssl_cert_path
  end

  def test_default_ssl_cert_file
    @config = PaypalAdaptive::Config.new("test", { "ssl_cert_file" => "" })
    assert File.exists?(@config.ssl_cert_file)
    assert_equal nil, @config.ssl_cert_path
  end

  def test_erb_tags
    ENV['paypal.username'] = 'account@email.com'
    ENV['paypal.password'] = 's3krit'
    
    config = PaypalAdaptive::Config.new("with_erb_tags")
    assert_equal 'account@email.com', config.headers["X-PAYPAL-SECURITY-USERID"]
    assert_equal 's3krit', config.headers["X-PAYPAL-SECURITY-PASSWORD"]
  end
end
```

Remove default config SSL file
user
```ruby
require 'test_helper'

class ConfigTest < Test::Unit::TestCase
  def test_set_ssl_cert_file
    @config = PaypalAdaptive::Config.new("test", { "ssl_cert_file" => "/path/to/cacert.pem" })
    assert_equal "/path/to/cacert.pem", @config.ssl_cert_file
    assert_equal nil, @config.ssl_cert_path
  end

  def test_erb_tags
    ENV['paypal.username'] = 'account@email.com'
    ENV['paypal.password'] = 's3krit'
    
    config = PaypalAdaptive::Config.new("with_erb_tags")
    assert_equal 'account@email.com', config.headers["X-PAYPAL-SECURITY-USERID"]
    assert_equal 's3krit', config.headers["X-PAYPAL-SECURITY-PASSWORD"]
  end
end
```
assistant