Allow selective linting

Closes #653

GETTING_STARTED.md

@@ -104,6 +104,18 @@ database, as built factories will create associated records. The provided
 example above uses the database_cleaner gem to clear out the database; be sure
 to add the gem to your Gemfile under the appropriate groups.
 
+You can lint factories selectively by passing only factories you want linted:
+
+```ruby
+factories_to_lint = FactoryGirl.factories.reject do |factory|
+  factory.name =~ /^old_/
+end
+
+FactoryGirl.lint factories_to_lint
+```
+
+This would lint all factories that aren't prefixed with `old_`.
+
 Defining factories
 ------------------
 

lib/factory_girl.rb

@@ -43,6 +43,7 @@ require 'factory_girl/decorator/class_key_hash'
 require 'factory_girl/decorator/disallows_duplicates_registry'
 require 'factory_girl/decorator/invocation_tracker'
 require 'factory_girl/decorator/new_constructor'
+require 'factory_girl/linter'
 require 'factory_girl/version'
 
 module FactoryGirl
@@ -54,24 +55,8 @@ module FactoryGirl
     @configuration = nil
   end
 
-  def self.lint
-    invalid_factories = FactoryGirl.factories.select do |factory|
-      built_factory = FactoryGirl.build(factory.name)
-
-      if built_factory.respond_to?(:valid?)
-        !built_factory.valid?
-      end
-    end
-
-    if invalid_factories.any?
-      error_message = <<-ERROR_MESSAGE.strip
-The following factories are invalid:
-
-#{invalid_factories.map {|factory| "* #{factory.name}" }.join("\n")}
-      ERROR_MESSAGE
-
-      raise InvalidFactoryError, error_message
-    end
+  def self.lint(factories_to_lint = FactoryGirl.factories)
+    Linter.lint!(factories_to_lint)
   end
 
   class << self

lib/factory_girl/linter.rb

@@ -0,0 +1,40 @@
+module FactoryGirl
+  class Linter
+    def self.lint!(factories_to_lint)
+      new(factories_to_lint).lint!
+    end
+
+    def initialize(factories_to_lint)
+      @factories_to_lint = factories_to_lint
+      @invalid_factories = calculate_invalid_factories
+    end
+
+    def lint!
+      if invalid_factories.any?
+        raise InvalidFactoryError, error_message
+      end
+    end
+
+    private
+
+    attr_reader :factories_to_lint, :invalid_factories
+
+    def calculate_invalid_factories
+      factories_to_lint.select do |factory|
+        built_factory = FactoryGirl.build(factory.name)
+
+        if built_factory.respond_to?(:valid?)
+          !built_factory.valid?
+        end
+      end
+    end
+
+    def error_message
+      <<-ERROR_MESSAGE.strip
+The following factories are invalid:
+
+#{invalid_factories.map {|factory| "* #{factory.name}" }.join("\n")}
+      ERROR_MESSAGE
+    end
+  end
+end

spec/acceptance/lint_spec.rb

@@ -52,4 +52,31 @@ The following factories are invalid:
     expect(Thing.new).not_to respond_to(:valid?)
     expect { FactoryGirl.lint }.not_to raise_error
   end
+
+  it 'allows for selective linting' do
+    define_class 'InvalidThing' do
+      def valid?
+        false
+      end
+    end
+
+    define_class 'ValidThing' do
+      def valid?
+        true
+      end
+    end
+
+    FactoryGirl.define do
+      factory :valid_thing
+      factory :invalid_thing
+    end
+
+    expect do
+      only_valid_factories = FactoryGirl.factories.reject do |factory|
+        factory.name =~ /invalid/
+      end
+
+      FactoryGirl.lint only_valid_factories
+    end.not_to raise_error
+  end
 end