Add expression support on the schema default

Example:

    create_table :posts do |t|
      t.datetime :published_at, default: -> { 'NOW()' }
    end

3 files changed, 36 insertions, 24 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/uuid_test.rb b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
index 3d90790367..7628075ad2 100644
--- a/activerecord/test/cases/adapters/postgresql/uuid_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
@@ -197,14 +197,14 @@ class PostgresqlUUIDGenerationTest < ActiveRecord::PostgreSQLTestCase
 
     def test_schema_dumper_for_uuid_primary_key
       schema = dump_table_schema "pg_uuids"
-      assert_match(/\bcreate_table "pg_uuids", id: :uuid, default: "uuid_generate_v1\(\)"/, schema)
-      assert_match(/t\.uuid   "other_uuid", default: "uuid_generate_v4\(\)"/, schema)
+      assert_match(/\bcreate_table "pg_uuids", id: :uuid, default: -> { "uuid_generate_v1\(\)" }/, schema)
+      assert_match(/t\.uuid   "other_uuid", default: -> { "uuid_generate_v4\(\)" }/, schema)
     end
 
     def test_schema_dumper_for_uuid_primary_key_with_custom_default
       schema = dump_table_schema "pg_uuids_2"
-      assert_match(/\bcreate_table "pg_uuids_2", id: :uuid, default: "my_uuid_generator\(\)"/, schema)
-      assert_match(/t\.uuid   "other_uuid_2", default: "my_uuid_generator\(\)"/, schema)
+      assert_match(/\bcreate_table "pg_uuids_2", id: :uuid, default: -> { "my_uuid_generator\(\)" }/, schema)
+      assert_match(/t\.uuid   "other_uuid_2", default: -> { "my_uuid_generator\(\)" }/, schema)
     end
   end
 end
diff --git a/activerecord/test/cases/defaults_test.rb b/activerecord/test/cases/defaults_test.rb
index fb2d3bd497..ab5641d2dd 100644
--- a/activerecord/test/cases/defaults_test.rb
+++ b/activerecord/test/cases/defaults_test.rb
@@ -1,4 +1,5 @@
 require "cases/helper"
+require 'support/schema_dumping_helper'
 require 'models/default'
 require 'models/entrant'
 
@@ -80,6 +81,20 @@ class DefaultStringsTest < ActiveRecord::TestCase
   end
 end
 
+if current_adapter?(:PostgreSQLAdapter)
+  class PostgresqlDefaultExpressionTest < ActiveRecord::TestCase
+    include SchemaDumpingHelper
+
+    test "schema dump includes default expression" do
+      output = dump_table_schema("defaults")
+      assert_match %r/t\.date\s+"modified_date",\s+default: -> { "\('now'::text\)::date" }/, output
+      assert_match %r/t\.date\s+"modified_date_function",\s+default: -> { "now\(\)" }/, output
+      assert_match %r/t\.datetime\s+"modified_time",\s+default: -> { "now\(\)" }/, output
+      assert_match %r/t\.datetime\s+"modified_time_function",\s+default: -> { "now\(\)" }/, output
+    end
+  end
+end
+
 if current_adapter?(:Mysql2Adapter)
   class DefaultsTestWithoutTransactionalFixtures < ActiveRecord::TestCase
     # ActiveRecord::Base#create! (and #save and other related methods) will
diff --git a/activerecord/test/schema/postgresql_specific_schema.rb b/activerecord/test/schema/postgresql_specific_schema.rb
index df0362573b..3a5d73a0ed 100644
--- a/activerecord/test/schema/postgresql_specific_schema.rb
+++ b/activerecord/test/schema/postgresql_specific_schema.rb
@@ -11,7 +11,23 @@ ActiveRecord::Schema.define do
     t.uuid :uuid_parent_id
   end
 
-  %w(postgresql_times postgresql_oids defaults postgresql_timestamp_with_zones
+  create_table :defaults, force: true do |t|
+    t.date :modified_date, default: -> { 'CURRENT_DATE' }
+    t.date :modified_date_function, default: -> { 'now()' }
+    t.date :fixed_date, default: '2004-01-01'
+    t.datetime :modified_time, default: -> { 'CURRENT_TIMESTAMP' }
+    t.datetime :modified_time_function, default: -> { 'now()' }
+    t.datetime :fixed_time, default: '2004-01-01 00:00:00.000000-00'
+    t.column :char1, 'char(1)', default: 'Y'
+    t.string :char2, limit: 50, default: 'a varchar field'
+    t.text :char3, default: 'a text field'
+    t.bigint :bigint_default, default: -> { '0::bigint' }
+    t.text :multiline_default, default: '--- []
+
+'
+  end
+
+  %w(postgresql_times postgresql_oids postgresql_timestamp_with_zones
       postgresql_partitioned_table postgresql_partitioned_table_parent).each do |table_name|
     drop_table table_name, if_exists: true
   end
@@ -28,25 +44,6 @@ ActiveRecord::Schema.define do
   end
 
   execute <<_SQL
-    CREATE TABLE defaults (
-    id serial primary key,
-    modified_date date default CURRENT_DATE,
-    modified_date_function date default now(),
-    fixed_date date default '2004-01-01',
-    modified_time timestamp default CURRENT_TIMESTAMP,
-    modified_time_function timestamp default now(),
-    fixed_time timestamp default '2004-01-01 00:00:00.000000-00',
-    char1 char(1) default 'Y',
-    char2 character varying(50) default 'a varchar field',
-    char3 text default 'a text field',
-    bigint_default bigint default 0::bigint,
-    multiline_default text DEFAULT '--- []
-
-'::text
-);
-_SQL
-
-  execute <<_SQL
   CREATE TABLE postgresql_times (
     id SERIAL PRIMARY KEY,
     time_interval INTERVAL,