PostgreSQL: `:collation` support for string and text columns

Example:

    create_table :foos do |t|
      t.string :string_en, collation: 'en_US.UTF-8'
      t.text   :text_ja,   collation: 'ja_JP.UTF-8'
    end

1 files changed, 53 insertions, 0 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/collation_test.rb b/activerecord/test/cases/adapters/postgresql/collation_test.rb
new file mode 100644
index 0000000000..17ef5f304c
--- /dev/null
+++ b/activerecord/test/cases/adapters/postgresql/collation_test.rb
@@ -0,0 +1,53 @@
+require "cases/helper"
+require 'support/schema_dumping_helper'
+
+class PostgresqlCollationTest < ActiveRecord::TestCase
+  include SchemaDumpingHelper
+
+  def setup
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table :postgresql_collations, force: true do |t|
+      t.string :string_c, collation: 'C'
+      t.text :text_posix, collation: 'POSIX'
+    end
+  end
+
+  def teardown
+    @connection.drop_table :postgresql_collations, if_exists: true
+  end
+
+  test "string column with collation" do
+    column = @connection.columns(:postgresql_collations).find { |c| c.name == 'string_c' }
+    assert_equal :string, column.type
+    assert_equal 'C', column.collation
+  end
+
+  test "text column with collation" do
+    column = @connection.columns(:postgresql_collations).find { |c| c.name == 'text_posix' }
+    assert_equal :text, column.type
+    assert_equal 'POSIX', column.collation
+  end
+
+  test "add column with collation" do
+    @connection.add_column :postgresql_collations, :title, :string, collation: 'C'
+
+    column = @connection.columns(:postgresql_collations).find { |c| c.name == 'title' }
+    assert_equal :string, column.type
+    assert_equal 'C', column.collation
+  end
+
+  test "change column with collation" do
+    @connection.add_column :postgresql_collations, :description, :string
+    @connection.change_column :postgresql_collations, :description, :text, collation: 'POSIX'
+
+    column = @connection.columns(:postgresql_collations).find { |c| c.name == 'description' }
+    assert_equal :text, column.type
+    assert_equal 'POSIX', column.collation
+  end
+
+  test "schema dump includes collation" do
+    output = dump_table_schema("postgresql_collations")
+    assert_match %r{t.string\s+"string_c",\s+collation: "C"$}, output
+    assert_match %r{t.text\s+"text_posix",\s+collation: "POSIX"$}, output
+  end
+end