Fix a typo in DatabaseTasks#current_config

This commit fixes a method typo that was introduced in #37199, also also
adds tests for the `DatabaseTasks#current_config` method given it's
current implementation.

While I was in here, I also made it so that if `current_config` is
called with an `env` it won't try to look up the `Rails.env`
potentially resulting in an error for non-Rails application.

IMO this method should be deprecated & removed as it's no longer used in
Rails, is confusing (for example: `test_current_config_read_after_set`),
and is currently dependent on Rails if `env` isn't passed.

Co-authored-by: eileencodes <eileencodes@gmail.com>

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -111,12 +111,13 @@ def seed_loader
       end
 
       def current_config(options = {})
-        options.reverse_merge! env: env
-        options[:spec] ||= "primary"
         if options.has_key?(:config)
           @current_config = options[:config]
         else
-          @current_config ||= ActiveRecord::Base.configurations.configs_for(env_name: options[:env], spec_name: options[:spec]).db_config.configuration_hash
+          env_name = options[:env] || env
+          spec_name = options[:spec] || "primary"
+
+          @current_config ||= ActiveRecord::Base.configurations.configs_for(env_name: env_name, spec_name: spec_name)&.configuration_hash
         end
       end
 

activerecord/test/cases/tasks/database_tasks_test.rb

@@ -112,6 +112,57 @@ def test_raises_an_error_if_no_migrations_have_been_made
     end
   end
 
+  class DatabaseTasksCurrentConfigTask < ActiveRecord::TestCase
+    def test_current_config_set
+      hash = {}
+
+      with_stubbed_configurations do
+        ActiveRecord::Tasks::DatabaseTasks.current_config(config: hash, env: "production")
+
+        assert_equal hash, ActiveRecord::Tasks::DatabaseTasks.current_config(env: "production")
+      end
+    end
+
+    def test_current_config_read_none_found
+      with_stubbed_configurations do
+        config = ActiveRecord::Tasks::DatabaseTasks.current_config(env: "production", spec: "empty")
+
+        assert_nil config
+      end
+    end
+
+    def test_current_config_read_found
+      with_stubbed_configurations do
+        config = ActiveRecord::Tasks::DatabaseTasks.current_config(env: "production", spec: "exists")
+
+        assert_equal({ database: "my-db" }, config)
+      end
+    end
+
+    def test_current_config_read_after_set
+      hash = {}
+
+      with_stubbed_configurations do
+        ActiveRecord::Tasks::DatabaseTasks.current_config(config: hash, env: "production")
+
+        config = ActiveRecord::Tasks::DatabaseTasks.current_config(env: "production", spec: "exists")
+
+        assert_equal hash, config
+      end
+    end
+
+    private
+      def with_stubbed_configurations
+        old_configurations = ActiveRecord::Base.configurations
+        ActiveRecord::Base.configurations = { "production" => { "exists" => { "database" => "my-db" } } }
+
+        yield
+      ensure
+        ActiveRecord::Base.configurations = old_configurations
+        ActiveRecord::Tasks::DatabaseTasks.current_config = nil
+      end
+  end
+
   class DatabaseTasksRegisterTask < ActiveRecord::TestCase
     def test_register_task
       klazz = Class.new do