Deprecate supports_migrations? on connection adapters

`supports_migrations?` was added at 4160b51 to determine if schema
statements (`create_table`, `drop_table`, etc) are implemented in the
adapter. But all tested databases has been supported migrations since
a4fc93c at least.

Author: kamipo

activerecord/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Deprecate `supports_migrations?` on connection adapters.
+
+    *Ryuta Kamizono*
+
 *   Fix regression of #1969 with SELECT aliases in HAVING clause.
 
     *Eugene Kenny*

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -232,10 +232,10 @@ def adapter_name
         self.class::ADAPTER_NAME
       end
 
-      # Does this adapter support migrations?
-      def supports_migrations?
-        false
+      def supports_migrations? # :nodoc:
+        true
       end
+      deprecate :supports_migrations?
 
       def supports_primary_key? # :nodoc:
         true

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -89,11 +89,6 @@ def mariadb? # :nodoc:
         /mariadb/i.match?(full_version)
       end
 
-      # Returns true, since this connection adapter supports migrations.
-      def supports_migrations?
-        true
-      end
-
       def supports_bulk_alter? #:nodoc:
         true
       end

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -281,11 +281,6 @@ def native_database_types #:nodoc:
         NATIVE_DATABASE_TYPES
       end
 
-      # Returns true, since this connection adapter supports migrations.
-      def supports_migrations?
-        true
-      end
-
       def set_standard_conforming_strings
         execute("SET standard_conforming_strings = on", "SCHEMA")
       end

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -117,11 +117,6 @@ def supports_statement_cache?
         true
       end
 
-      # Returns true, since this connection adapter supports migrations.
-      def supports_migrations? #:nodoc:
-        true
-      end
-
       def requires_reloading?
         true
       end

activerecord/lib/active_record/migration.rb

@@ -548,12 +548,10 @@ def initialize(app)
       end
 
       def call(env)
-        if connection.supports_migrations?
-          mtime = ActiveRecord::Migrator.last_migration.mtime.to_i
-          if @last_check < mtime
-            ActiveRecord::Migration.check_pending!(connection)
-            @last_check = mtime
-          end
+        mtime = ActiveRecord::Migrator.last_migration.mtime.to_i
+        if @last_check < mtime
+          ActiveRecord::Migration.check_pending!(connection)
+          @last_check = mtime
         end
         @app.call(env)
       end
@@ -1098,8 +1096,6 @@ def move(direction, migrations_paths, steps)
     end
 
     def initialize(direction, migrations, target_version = nil)
-      raise StandardError.new("This database does not yet support migrations") unless Base.connection.supports_migrations?
-
       @direction         = direction
       @target_version    = target_version
       @migrated_versions = nil

activerecord/lib/active_record/railties/databases.rake

@@ -288,8 +288,7 @@ db_namespace = namespace :db do
       current_config = ActiveRecord::Tasks::DatabaseTasks.current_config
       ActiveRecord::Tasks::DatabaseTasks.structure_dump(current_config, filename)
 
-      if ActiveRecord::Base.connection.supports_migrations? &&
-          ActiveRecord::SchemaMigration.table_exists?
+      if ActiveRecord::SchemaMigration.table_exists?
         File.open(filename, "a") do |f|
           f.puts ActiveRecord::Base.connection.dump_schema_information
           f.print "\n"

activerecord/test/cases/ar_schema_test.rb

@@ -1,146 +1,143 @@
 require "cases/helper"
 
-if ActiveRecord::Base.connection.supports_migrations?
+class ActiveRecordSchemaTest < ActiveRecord::TestCase
+  self.use_transactional_tests = false
+
+  setup do
+    @original_verbose = ActiveRecord::Migration.verbose
+    ActiveRecord::Migration.verbose = false
+    @connection = ActiveRecord::Base.connection
+    ActiveRecord::SchemaMigration.drop_table
+  end
 
-  class ActiveRecordSchemaTest < ActiveRecord::TestCase
-    self.use_transactional_tests = false
+  teardown do
+    @connection.drop_table :fruits rescue nil
+    @connection.drop_table :nep_fruits rescue nil
+    @connection.drop_table :nep_schema_migrations rescue nil
+    @connection.drop_table :has_timestamps rescue nil
+    @connection.drop_table :multiple_indexes rescue nil
+    ActiveRecord::SchemaMigration.delete_all rescue nil
+    ActiveRecord::Migration.verbose = @original_verbose
+  end
 
-    setup do
-      @original_verbose = ActiveRecord::Migration.verbose
-      ActiveRecord::Migration.verbose = false
-      @connection = ActiveRecord::Base.connection
-      ActiveRecord::SchemaMigration.drop_table
-    end
+  def test_has_primary_key
+    old_primary_key_prefix_type = ActiveRecord::Base.primary_key_prefix_type
+    ActiveRecord::Base.primary_key_prefix_type = :table_name_with_underscore
+    assert_equal "version", ActiveRecord::SchemaMigration.primary_key
 
-    teardown do
-      @connection.drop_table :fruits rescue nil
-      @connection.drop_table :nep_fruits rescue nil
-      @connection.drop_table :nep_schema_migrations rescue nil
-      @connection.drop_table :has_timestamps rescue nil
-      @connection.drop_table :multiple_indexes rescue nil
-      ActiveRecord::SchemaMigration.delete_all rescue nil
-      ActiveRecord::Migration.verbose = @original_verbose
+    ActiveRecord::SchemaMigration.create_table
+    assert_difference "ActiveRecord::SchemaMigration.count", 1 do
+      ActiveRecord::SchemaMigration.create version: 12
     end
+  ensure
+    ActiveRecord::SchemaMigration.drop_table
+    ActiveRecord::Base.primary_key_prefix_type = old_primary_key_prefix_type
+  end
 
-    def test_has_primary_key
-      old_primary_key_prefix_type = ActiveRecord::Base.primary_key_prefix_type
-      ActiveRecord::Base.primary_key_prefix_type = :table_name_with_underscore
-      assert_equal "version", ActiveRecord::SchemaMigration.primary_key
-
-      ActiveRecord::SchemaMigration.create_table
-      assert_difference "ActiveRecord::SchemaMigration.count", 1 do
-        ActiveRecord::SchemaMigration.create version: 12
+  def test_schema_define
+    ActiveRecord::Schema.define(version: 7) do
+      create_table :fruits do |t|
+        t.column :color, :string
+        t.column :fruit_size, :string  # NOTE: "size" is reserved in Oracle
+        t.column :texture, :string
+        t.column :flavor, :string
       end
-    ensure
-      ActiveRecord::SchemaMigration.drop_table
-      ActiveRecord::Base.primary_key_prefix_type = old_primary_key_prefix_type
     end
 
-    def test_schema_define
-      ActiveRecord::Schema.define(version: 7) do
-        create_table :fruits do |t|
-          t.column :color, :string
-          t.column :fruit_size, :string  # NOTE: "size" is reserved in Oracle
-          t.column :texture, :string
-          t.column :flavor, :string
-        end
-      end
-
-      assert_nothing_raised { @connection.select_all "SELECT * FROM fruits" }
-      assert_nothing_raised { @connection.select_all "SELECT * FROM schema_migrations" }
-      assert_equal 7, ActiveRecord::Migrator::current_version
-    end
+    assert_nothing_raised { @connection.select_all "SELECT * FROM fruits" }
+    assert_nothing_raised { @connection.select_all "SELECT * FROM schema_migrations" }
+    assert_equal 7, ActiveRecord::Migrator::current_version
+  end
 
-    def test_schema_define_w_table_name_prefix
-      table_name = ActiveRecord::SchemaMigration.table_name
-      old_table_name_prefix = ActiveRecord::Base.table_name_prefix
-      ActiveRecord::Base.table_name_prefix = "nep_"
-      ActiveRecord::SchemaMigration.table_name = "nep_#{table_name}"
-      ActiveRecord::Schema.define(version: 7) do
-        create_table :fruits do |t|
-          t.column :color, :string
-          t.column :fruit_size, :string  # NOTE: "size" is reserved in Oracle
-          t.column :texture, :string
-          t.column :flavor, :string
-        end
+  def test_schema_define_w_table_name_prefix
+    table_name = ActiveRecord::SchemaMigration.table_name
+    old_table_name_prefix = ActiveRecord::Base.table_name_prefix
+    ActiveRecord::Base.table_name_prefix = "nep_"
+    ActiveRecord::SchemaMigration.table_name = "nep_#{table_name}"
+    ActiveRecord::Schema.define(version: 7) do
+      create_table :fruits do |t|
+        t.column :color, :string
+        t.column :fruit_size, :string  # NOTE: "size" is reserved in Oracle
+        t.column :texture, :string
+        t.column :flavor, :string
       end
-      assert_equal 7, ActiveRecord::Migrator::current_version
-    ensure
-      ActiveRecord::Base.table_name_prefix = old_table_name_prefix
-      ActiveRecord::SchemaMigration.table_name = table_name
     end
+    assert_equal 7, ActiveRecord::Migrator::current_version
+  ensure
+    ActiveRecord::Base.table_name_prefix = old_table_name_prefix
+    ActiveRecord::SchemaMigration.table_name = table_name
+  end
 
-    def test_schema_raises_an_error_for_invalid_column_type
-      assert_raise NoMethodError do
-        ActiveRecord::Schema.define(version: 8) do
-          create_table :vegetables do |t|
-            t.unknown :color
-          end
+  def test_schema_raises_an_error_for_invalid_column_type
+    assert_raise NoMethodError do
+      ActiveRecord::Schema.define(version: 8) do
+        create_table :vegetables do |t|
+          t.unknown :color
         end
       end
     end
+  end
 
-    def test_schema_subclass
-      Class.new(ActiveRecord::Schema).define(version: 9) do
-        create_table :fruits
-      end
-      assert_nothing_raised { @connection.select_all "SELECT * FROM fruits" }
+  def test_schema_subclass
+    Class.new(ActiveRecord::Schema).define(version: 9) do
+      create_table :fruits
     end
+    assert_nothing_raised { @connection.select_all "SELECT * FROM fruits" }
+  end
 
-    def test_normalize_version
-      assert_equal "118", ActiveRecord::SchemaMigration.normalize_migration_number("0000118")
-      assert_equal "002", ActiveRecord::SchemaMigration.normalize_migration_number("2")
-      assert_equal "017", ActiveRecord::SchemaMigration.normalize_migration_number("0017")
-      assert_equal "20131219224947", ActiveRecord::SchemaMigration.normalize_migration_number("20131219224947")
-    end
+  def test_normalize_version
+    assert_equal "118", ActiveRecord::SchemaMigration.normalize_migration_number("0000118")
+    assert_equal "002", ActiveRecord::SchemaMigration.normalize_migration_number("2")
+    assert_equal "017", ActiveRecord::SchemaMigration.normalize_migration_number("0017")
+    assert_equal "20131219224947", ActiveRecord::SchemaMigration.normalize_migration_number("20131219224947")
+  end
 
-    def test_schema_load_with_multiple_indexes_for_column_of_different_names
-      ActiveRecord::Schema.define do
-        create_table :multiple_indexes do |t|
-          t.string "foo"
-          t.index ["foo"], name: "multiple_indexes_foo_1"
-          t.index ["foo"], name: "multiple_indexes_foo_2"
-        end
+  def test_schema_load_with_multiple_indexes_for_column_of_different_names
+    ActiveRecord::Schema.define do
+      create_table :multiple_indexes do |t|
+        t.string "foo"
+        t.index ["foo"], name: "multiple_indexes_foo_1"
+        t.index ["foo"], name: "multiple_indexes_foo_2"
       end
+    end
 
-      indexes = @connection.indexes("multiple_indexes")
+    indexes = @connection.indexes("multiple_indexes")
 
-      assert_equal 2, indexes.length
-      assert_equal ["multiple_indexes_foo_1", "multiple_indexes_foo_2"], indexes.collect(&:name).sort
-    end
+    assert_equal 2, indexes.length
+    assert_equal ["multiple_indexes_foo_1", "multiple_indexes_foo_2"], indexes.collect(&:name).sort
+  end
 
-    def test_timestamps_without_null_set_null_to_false_on_create_table
-      ActiveRecord::Schema.define do
-        create_table :has_timestamps do |t|
-          t.timestamps
-        end
+  def test_timestamps_without_null_set_null_to_false_on_create_table
+    ActiveRecord::Schema.define do
+      create_table :has_timestamps do |t|
+        t.timestamps
       end
-
-      assert !@connection.columns(:has_timestamps).find { |c| c.name == "created_at" }.null
-      assert !@connection.columns(:has_timestamps).find { |c| c.name == "updated_at" }.null
     end
 
-    def test_timestamps_without_null_set_null_to_false_on_change_table
-      ActiveRecord::Schema.define do
-        create_table :has_timestamps
+    assert !@connection.columns(:has_timestamps).find { |c| c.name == "created_at" }.null
+    assert !@connection.columns(:has_timestamps).find { |c| c.name == "updated_at" }.null
+  end
 
-        change_table :has_timestamps do |t|
-          t.timestamps default: Time.now
-        end
-      end
+  def test_timestamps_without_null_set_null_to_false_on_change_table
+    ActiveRecord::Schema.define do
+      create_table :has_timestamps
 
-      assert !@connection.columns(:has_timestamps).find { |c| c.name == "created_at" }.null
-      assert !@connection.columns(:has_timestamps).find { |c| c.name == "updated_at" }.null
+      change_table :has_timestamps do |t|
+        t.timestamps default: Time.now
+      end
     end
 
-    def test_timestamps_without_null_set_null_to_false_on_add_timestamps
-      ActiveRecord::Schema.define do
-        create_table :has_timestamps
-        add_timestamps :has_timestamps, default: Time.now
-      end
+    assert !@connection.columns(:has_timestamps).find { |c| c.name == "created_at" }.null
+    assert !@connection.columns(:has_timestamps).find { |c| c.name == "updated_at" }.null
+  end
 
-      assert !@connection.columns(:has_timestamps).find { |c| c.name == "created_at" }.null
-      assert !@connection.columns(:has_timestamps).find { |c| c.name == "updated_at" }.null
+  def test_timestamps_without_null_set_null_to_false_on_add_timestamps
+    ActiveRecord::Schema.define do
+      create_table :has_timestamps
+      add_timestamps :has_timestamps, default: Time.now
     end
+
+    assert !@connection.columns(:has_timestamps).find { |c| c.name == "created_at" }.null
+    assert !@connection.columns(:has_timestamps).find { |c| c.name == "updated_at" }.null
   end
 end