Set environment even when no migration runs

This PR addresses the issue described in https://github.com/rails/rails/pull/22967#issuecomment-170251635. If the database is non empty and has no new migrations than `db:migrate` will not set the environment. This PR works by always setting the environment value on successful `up` migration regardless of whether or not a migration was actually executed.

2 files changed, 37 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 471c5dc05a..8dedd4c8a2 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -1170,6 +1170,8 @@ module ActiveRecord
       migration = migrations.detect { |m| m.version == @target_version }
       raise UnknownMigrationVersionError.new(@target_version) if migration.nil?
       execute_migration_in_transaction(migration, @direction)
+
+      record_environment
     end
 
     # Used for running multiple migrations up to or down to a certain value.
@@ -1181,6 +1183,14 @@ module ActiveRecord
       runnable.each do |migration|
         execute_migration_in_transaction(migration, @direction)
       end
+
+      record_environment
+    end
+
+    # Stores the current environment in the database.
+    def record_environment
+      return if down?
+      ActiveRecord::InternalMetadata[:environment] = ActiveRecord::Migrator.current_environment
     end
 
     def ran?(migration)
@@ -1236,7 +1246,6 @@ module ActiveRecord
       else
         migrated << version
         ActiveRecord::SchemaMigration.create!(version: version.to_s)
-        ActiveRecord::InternalMetadata[:environment] = ActiveRecord::Migrator.current_environment
       end
     end
 
diff --git a/activerecord/test/cases/migration_test.rb b/activerecord/test/cases/migration_test.rb
index 4d264caffb..fe74ca127f 100644
--- a/activerecord/test/cases/migration_test.rb
+++ b/activerecord/test/cases/migration_test.rb
@@ -398,6 +398,33 @@ class MigrationTest < ActiveRecord::TestCase
     ENV["RACK_ENV"]  = original_rack_env
   end
 
+
+  def test_migration_sets_internal_metadata_even_when_fully_migrated
+    current_env     = ActiveRecord::ConnectionHandling::DEFAULT_ENV.call
+    migrations_path = MIGRATIONS_ROOT + "/valid"
+    old_path        = ActiveRecord::Migrator.migrations_paths
+    ActiveRecord::Migrator.migrations_paths = migrations_path
+
+    ActiveRecord::Migrator.up(migrations_path)
+    assert_equal current_env, ActiveRecord::InternalMetadata[:environment]
+
+    original_rails_env  = ENV["RAILS_ENV"]
+    original_rack_env   = ENV["RACK_ENV"]
+    ENV["RAILS_ENV"]    = ENV["RACK_ENV"] = "foofoo"
+    new_env     = ActiveRecord::ConnectionHandling::DEFAULT_ENV.call
+
+    refute_equal current_env, new_env
+
+    sleep 1 # mysql by default does not store fractional seconds in the database
+
+    ActiveRecord::Migrator.up(migrations_path)
+    assert_equal new_env, ActiveRecord::InternalMetadata[:environment]
+  ensure
+    ActiveRecord::Migrator.migrations_paths = old_path
+    ENV["RAILS_ENV"] = original_rails_env
+    ENV["RACK_ENV"]  = original_rack_env
+  end
+
   def test_proper_table_name_on_migration
     reminder_class = new_isolated_reminder_class
     migration = ActiveRecord::Migration.new