Refactor gateway selector error handling

lib/active_merchant/billing/base.rb

@@ -31,8 +31,15 @@ def self.mode=(mode)
       #
       #   ActiveMerchant::Billing::Base.gateway('moneris').new
       def self.gateway(name)
-        raise NameError if (name_str = name.to_s.downcase).blank?
-        Billing.const_get("#{name_str}_gateway".camelize)
+        name_str = name.to_s.strip.downcase
+
+        raise(ArgumentError, 'A gateway provider must be specified') if name_str.blank?
+
+        begin
+          Billing.const_get("#{name_str}_gateway".camelize)
+        rescue
+          raise ArgumentError, "The specified gateway is not valid (#{name_str})"
+        end
       end
 
       # Return the matching integration module

test/unit/base_test.rb

@@ -18,18 +18,32 @@ def test_should_return_a_new_gateway_specified_by_symbol_name
     assert_equal LinkpointGateway,     Base.gateway(:linkpoint)
   end
 
-  def test_should_raise_when_invalid_gateway_is_passed
-    assert_raise NameError do
-      Base.gateway(:nil)
+  def test_should_raise_when_nil_gateway_is_passed
+    e = assert_raise ArgumentError do
+      Base.gateway(nil)
     end
+    assert_equal 'A gateway provider must be specified', e.message
+  end
 
-    assert_raise NameError do
+  def test_should_raise_when_empty_gateway_is_passed
+    e = assert_raise ArgumentError do
       Base.gateway('')
     end
+    assert_equal 'A gateway provider must be specified', e.message
+  end
 
-    assert_raise NameError do
+  def test_should_raise_when_invalid_gateway_symbol_is_passed
+    e = assert_raise ArgumentError do
       Base.gateway(:hotdog)
     end
+    assert_equal 'The specified gateway is not valid (hotdog)', e.message
+  end
+
+  def test_should_raise_when_invalid_gateway_string_is_passed
+    e = assert_raise ArgumentError do
+      Base.gateway('hotdog')
+    end
+    assert_equal 'The specified gateway is not valid (hotdog)', e.message
   end
 
   def test_should_return_an_integration_by_name