rails 5.2.4.3 raises PendingMigrationsError when using NullDB

[coldnebo]

ERROR

Trying to run 'rake spec' while using nulldb I get this error:

$ rake spec
Migrations are pending. To resolve this issue, run:

        bin/rails db:migrate RAILS_ENV=test

CONFIGURATION

• The Rails app has migrations in db/migrations.
• We are using the default rails_helper.rb from rspec-rails, which runs under RAILS_ENV='test'

Environment:

ruby 2.6.6 (linux)
rails (5.2.4.3)
rspec-rails (4.0.1)
activerecord (5.2.4.3)
activerecord-nulldb-adapter (0.4.0)

database.yml defines

test: 
  adapter: nulldb

WORKAROUND

Adding this to the end of config/environments/test.rb fixes the problem and allows the specs to run:

module ActiveRecord
  class MigrationContext 
    def needs_migration?
      false
    end
  end
end

[ekohl]

I also ran into this. A more flexible patch is:

module NullDBMigrationContextPatch
  def needs_migration?
    return false if schema_migration.connection.adapter_name == 'NullDB'
    super
  end
end

class ActiveRecord::MigrationContext
  prepend NullDBMigrationContextPatch
end

[coldnebo]

That is very slick! Thanks!

[cabello]

Leaving this as pinned but closing for now.