tasks/database.rake @@ -3,21 +3,40 @@ == What NullDB is a Rails database connection adapter that interprets common -database operations as no-ops. +database operations as no-ops. It is the Null Object pattern as +applied to database adapters. == How -In your database.yml: +Once installed, NullDB can be used much like any other ActiveRecord +database adapter: + + ActiveRecord::Base.establish_connection :adapter => nulldb + +NullDB needs to know where you keep your schema file in order to +reflect table metadata. By default it looks in +RAILS_ROOT/db/schema.rb. You can override that by setting the ++schema+ option: + + ActiveRecord::Base.establish_connection :adapter => nulldb, + :schema => foo/myschema.rb + +There is a helper method included for configuring RSpec sessions to +use NullDB. Just put the following in your spec/spec_helper.rb: + + Spec::Runner.configure do |config| + ::NullDB.insinuate_into_spec(config) + end + +You can also experiment with putting NullDB in your database.yml: unit_test: adapter: nulldb -That's all there is to it. Now any code run in the +unit_test+ -environment, *including* schema definitions, will execute using the -NullDB database connector. Most simple database operations will be -safe no-ops. If a schema definition is executed - which is normally -done automatically before unit tests and specs in Rails - NullDB will -use the schema information to reflect table and column metadata. +However, due to the way Rails hard-codes specific database adapters +into its standard Rake tasks, you may find that this generates +unexpected and difficult-to-debug behavior. Workarounds for this are +under development. == Why @@ -31,19 +50,19 @@ UnitRecord[http://unit-test-ar.rubyforge.org/] libraries. It differs from them in a couple of ways: 1. It works. At the time of writing both ARBS and UnitRecord were - broken out of the box when used with Rails 2.0. + not working for me out of the box with Rails 2.0. -2. It avoids monkey-patching. Rather than re-wiring the secret inner - workings of ActiveRecord (and thus being tightly coupled to said - inner workings), NullDB implements the same well-documented public - interface that the other standard database adapters, like MySQL - and SQLServer, implement. +2. It avoids monkey-patching as much as possible. Rather than + re-wiring the secret inner workings of ActiveRecord (and thus being + tightly coupled to those inner workings), NullDB implements the + same [semi-]well-documented public interface that the other standard + database adapters, like MySQL and SQLServer, implement. 3. UnitRecord takes the approach of eliminating database interaction in tests by turning almost every database interaction into an - exception. NullDB recognizes that today's ActiveRecord objects - can't take two steps without consulting the database, and instead - turns database interactions into safe no-ops. + exception. NullDB recognizes that ActiveRecord objects typically + can't take two steps without consulting the database, so instead it + turns database interactions into no-ops. One concrete advantage of this null-object pattern design is that it is possible with NullDB to test +after_save+ hooks. With NullDB, you @@ -60,7 +79,7 @@ nothing will be saved. == Who -NullDB was written by Avdi Grimm <avdi@avdi.org> +NullDB was written by Avdi Grimm <mailto:avdi@avdi.org> == License README @@ -9,5 +9,5 @@ end Rake::RDocTask.new do |rd| rd.main = "README" - rd.rdoc_files.include("README", "lib/**/*.rb") + rd.rdoc_files.include("README", "LICENSE", "lib/**/*.rb") end Rakefile @@ -1 +1,3 @@ -# Nothing do to here... +require 'active_record/connection_adapters/nulldb_adapter' + +::NullDB = ActiveRecord::ConnectionAdapters::NullDB init.rb @@ -1,25 +1,45 @@ require 'logger' require 'stringio' +require 'singleton' require 'active_record/connection_adapters/abstract_adapter' class ActiveRecord::Base + # Instantiate a new NullDB connection. Used by ActiveRecord internally. def self.nulldb_connection(config) - ActiveRecord::ConnectionAdapters::NullDB.new + ActiveRecord::ConnectionAdapters::NullDB.new(config) end end class ActiveRecord::ConnectionAdapters::NullDB < ActiveRecord::ConnectionAdapters::AbstractAdapter + TableDefinition = ActiveRecord::ConnectionAdapters::TableDefinition + + # A convenience method for integratinginto RSpec. See README for example of + # use. + def self.insinuate_into_spec(config) + config.before :all do + ActiveRecord::Base.establish_connection(:adapter => :nulldb) + end + + config.after :all do + ActiveRecord::Base.establish_connection(:test) + end + end + def self.execution_log (@@execution_log ||= []) end - def initialize + # Recognized options: + # + # [+:schema+] path to the schema file, relative to RAILS_ROOT + def initialize(config={}) @log = StringIO.new @logger = Logger.new(@log) - @tables = {} @last_unique_id = 0 + @tables = {'schema_info' => TableDefinition.new(nil)} + @schema_path = config.fetch(:schema){ "db/schema.rb" } super(nil, @logger) end @@ -42,12 +62,21 @@ class ActiveRecord::ConnectionAdapters::NullDB < @tables[table_name] = table_definition end + def tables + @tables.keys.map(&:to_s) + end + def columns(table_name, name = nil) - @tables[table_name].columns.map do |col_def| + if @tables.size <= 1 + ActiveRecord::Migration.verbose = false + Kernel.load(File.join(RAILS_ROOT, @schema_path)) + end + table = @tables[table_name] + table.columns.map do |col_def| ActiveRecord::ConnectionAdapters::Column.new(col_def.name.to_s, - col_def.default, - col_def.type, - col_def.null) + col_def.default, + col_def.type, + col_def.null) end end @@ -60,6 +89,10 @@ class ActiveRecord::ConnectionAdapters::NullDB < object_id || next_unique_id end + def select(statement, name) + [] + end + private def next_unique_id lib/active_record/connection_adapters/nulldb_adapter.rb @@ -9,6 +9,35 @@ class Employee < ActiveRecord::Base end end +RAILS_ROOT = "RAILS_ROOT" + +describe "NullDB with no schema pre-loaded" do + before :each do + Kernel.stub!(:load) + ActiveRecord::Migration.stub!(:verbose=) + end + + it "should load RAILS_ROOT/db/schema.rb if no alternate is specified" do + ActiveRecord::Base.establish_connection :adapter => :nulldb + Kernel.should_receive(:load).with("RAILS_ROOT/db/schema.rb") + ActiveRecord::Base.connection.columns('schema_info') + end + + it "should load the specified schema relative to RAILS_ROOT" do + Kernel.should_receive(:load).with("RAILS_ROOT/foo/myschema.rb") + ActiveRecord::Base.establish_connection :adapter => :nulldb, + :schema => "foo/myschema.rb" + ActiveRecord::Base.connection.columns('schema_info') + end + + it "should suppress migration output" do + ActiveRecord::Migration.should_receive(:verbose=).with(false) + ActiveRecord::Base.establish_connection :adapter => :nulldb, + :schema => "foo/myschema.rb" + ActiveRecord::Base.connection.columns('schema_info') + end +end + describe "NullDB" do before :all do ActiveRecord::Base.establish_connection :adapter => :nulldb @@ -88,6 +117,14 @@ describe "NullDB" do @employee.connection.supports_migrations?.should be_true end + it "should always have a schema_info table definition" do + @employee.connection.tables.should include("schema_info") + end + + it "should return an empty array from #select" do + @employee.connection.select("who cares", "blah").should == [] + end + def should_have_column(klass, col_name, col_type) col = klass.columns_hash[col_name.to_s] col.should_not be_nil spec/nulldb_spec.rb a19a383225e06d6f291950b4f1e80a7b8284c459 Avdi Grimm avdi@avdi.org http://github.com/technicalpickles/nulldb/commit/2e46b54bbbd4dfba807d47de4002eb2c08987c4d 2e46b54bbbd4dfba807d47de4002eb2c08987c4d 2008-02-17T21:34:16-08:00 2008-02-17T21:34:16-08:00 * Actually works in a real world project. * Updated documentation. eae2a7417244eea5571a77c571f1e8c787e53d67 Avdi Grimm avdi@avdi.org