Move SchemaMigration to migration_context

This PR moves the `schema_migration` to `migration_context` so that we
can access the `schema_migration` per connection.

This does not change behavior of the SchemaMigration if you are using
one database. This also does not change behavior of any public APIs.
`Migrator` is private as is `MigrationContext` so we can change these as
needed.

We now need to pass a `schema_migration` to `Migrator` so that we can
run migrations on the right connection outside the context of a rake
task.

The bugs this fixes were discovered while debugging the issues around
the SchemaCache on initialization with multiple database. It was clear
that `get_all_versions` wouldn't work without these changes outside the
context of a rake task (because in the rake task we establish a
connection and change AR::Base.connection to the db we're running on).

Because the `SchemaCache` relies on the `SchemaMigration` information we
need to make sure we store it per-connection rather than on
ActiveRecord::Base.

[Eileen M. Uchitelle & Aaron Patterson]

2 files changed, 20 insertions, 18 deletions

diff --git a/activerecord/test/cases/migration/compatibility_test.rb b/activerecord/test/cases/migration/compatibility_test.rb
index 726ccf925e..ff2a694e66 100644
--- a/activerecord/test/cases/migration/compatibility_test.rb
+++ b/activerecord/test/cases/migration/compatibility_test.rb
@@ -12,6 +12,7 @@ module ActiveRecord
       def setup
         super
         @connection = ActiveRecord::Base.connection
+        @schema_migration = @connection.schema_migration
         @verbose_was = ActiveRecord::Migration.verbose
         ActiveRecord::Migration.verbose = false
 
@@ -38,7 +39,7 @@ module ActiveRecord
         }.new
 
         assert connection.index_exists?(:testings, :foo, name: "custom_index_name")
-        assert_raise(StandardError) { ActiveRecord::Migrator.new(:up, [migration]).migrate }
+        assert_raise(StandardError) { ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate }
         assert connection.index_exists?(:testings, :foo, name: "custom_index_name")
       end
 
@@ -53,7 +54,7 @@ module ActiveRecord
         }.new
 
         assert connection.index_exists?(:testings, :bar)
-        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
         assert_not connection.index_exists?(:testings, :bar)
       end
 
@@ -67,7 +68,7 @@ module ActiveRecord
           end
         }.new
 
-        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
         assert_not connection.index_exists?(:more_testings, :foo_id)
         assert_not connection.index_exists?(:more_testings, :bar_id)
@@ -84,7 +85,7 @@ module ActiveRecord
           end
         }.new
 
-        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
         assert connection.column_exists?(:more_testings, :created_at, null: true)
         assert connection.column_exists?(:more_testings, :updated_at, null: true)
@@ -101,7 +102,7 @@ module ActiveRecord
           end
         }.new
 
-        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
         assert connection.column_exists?(:testings, :created_at, null: true)
         assert connection.column_exists?(:testings, :updated_at, null: true)
@@ -117,7 +118,7 @@ module ActiveRecord
             end
           }.new
 
-          ActiveRecord::Migrator.new(:up, [migration]).migrate
+          ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
           assert connection.column_exists?(:testings, :created_at, null: true)
           assert connection.column_exists?(:testings, :updated_at, null: true)
@@ -131,7 +132,7 @@ module ActiveRecord
           end
         }.new
 
-        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
         assert connection.column_exists?(:testings, :created_at, null: true)
         assert connection.column_exists?(:testings, :updated_at, null: true)
@@ -146,7 +147,7 @@ module ActiveRecord
           end
         }.new
 
-        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
         assert connection.column_exists?(:more_testings, :created_at, null: false, **precision_implicit_default)
         assert connection.column_exists?(:more_testings, :updated_at, null: false, **precision_implicit_default)
@@ -163,7 +164,7 @@ module ActiveRecord
           end
         }.new
 
-        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
         assert connection.column_exists?(:testings, :created_at, null: false, **precision_implicit_default)
         assert connection.column_exists?(:testings, :updated_at, null: false, **precision_implicit_default)
@@ -179,7 +180,7 @@ module ActiveRecord
             end
           }.new
 
-          ActiveRecord::Migrator.new(:up, [migration]).migrate
+          ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
           assert connection.column_exists?(:testings, :created_at, null: false, **precision_implicit_default)
           assert connection.column_exists?(:testings, :updated_at, null: false, **precision_implicit_default)
@@ -193,7 +194,7 @@ module ActiveRecord
           end
         }.new
 
-        ActiveRecord::Migrator.new(:up, [migration]).migrate
+        ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
         assert connection.column_exists?(:testings, :created_at, null: false, **precision_implicit_default)
         assert connection.column_exists?(:testings, :updated_at, null: false, **precision_implicit_default)
@@ -230,7 +231,7 @@ module ActiveRecord
             end
           }.new
 
-          ActiveRecord::Migrator.new(:up, [migration]).migrate
+          ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
           assert connection.column_exists?(:testings, :foo, comment: "comment")
         end
 
@@ -243,7 +244,7 @@ module ActiveRecord
             end
           }.new
 
-          ActiveRecord::Migrator.new(:up, [migration]).migrate
+          ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
 
           assert_equal "comment", connection.table_comment("testings")
         end
@@ -261,7 +262,7 @@ module ActiveRecord
           }.new
 
           Testing.create!
-          ActiveRecord::Migrator.new(:up, [migration]).migrate
+          ActiveRecord::Migrator.new(:up, [migration], @schema_migration).migrate
           assert_equal ["foobar"], Testing.all.map(&:foo)
         ensure
           ActiveRecord::Base.clear_cache!
diff --git a/activerecord/test/cases/migration/logger_test.rb b/activerecord/test/cases/migration/logger_test.rb
index 28f4cc124b..431047f957 100644
--- a/activerecord/test/cases/migration/logger_test.rb
+++ b/activerecord/test/cases/migration/logger_test.rb
@@ -17,19 +17,20 @@ module ActiveRecord
 
       def setup
         super
-        ActiveRecord::SchemaMigration.create_table
-        ActiveRecord::SchemaMigration.delete_all
+        @schema_migration = ActiveRecord::Base.connection.schema_migration
+        @schema_migration.create_table
+        @schema_migration.delete_all
       end
 
       teardown do
-        ActiveRecord::SchemaMigration.drop_table
+        @schema_migration.drop_table
       end
 
       def test_migration_should_be_run_without_logger
         previous_logger = ActiveRecord::Base.logger
         ActiveRecord::Base.logger = nil
         migrations = [Migration.new("a", 1), Migration.new("b", 2), Migration.new("c", 3)]
-        ActiveRecord::Migrator.new(:up, migrations).migrate
+        ActiveRecord::Migrator.new(:up, migrations, @schema_migration).migrate
       ensure
         ActiveRecord::Base.logger = previous_logger
       end