Issue #3357733: Provide Drush command to enforce configs

features/drush-command.feature

+@drush-command
+Feature: A Drush command to enforce configs
+  In order to reliably import configs from the filesystem
+  As a DevOps Engineer
+  I need to run a Drush command to enforce configs.
+
+  Background:
+    Given I run 'cd ..; make install'
+
+  Scenario: The `config-enforce:enforce` Drush command exists.
+    When I run 'drush list'
+    Then I should get:
+    """
+    config-enforce:enforce
+    """
+    When I run 'drush config-enforce:enforce --help'
+    Then I should get:
+    """
+    Import any configuration that has changed from that on the filesystem.
+    Examples:
+      config-enforce:enforce Enforce configuration.
+    Aliases: cee
+    """
+    When I run 'drush cee --help'
+    Then I should get:
+    """
+    Import any configuration that has changed from that on the filesystem.
+    Examples:
+      config-enforce:enforce Enforce configuration.
+    Aliases: cee
+    """
+
+  Scenario: A target module's optional configs are not imported when it is enabled.
+    When I am on the homepage
+    Then I should see "Config Enforce Devel"
+     And I should not see "Config Enforce Devel -- Test for Drush"
+     And I should not see "Drush command appears to work!"
+    When I run 'drush pm-enable -y ce_test_drush_command'
+     And I am on the homepage
+    Then I should see "Config Enforce Devel"
+     And I should not see "Config Enforce Devel -- Test for Drush"
+     And I should not see "Drush command appears to work!"
+
+  Scenario: Configs in a module's `config/optional` are imported when our Drush command is run.
+    When I run 'drush pm-enable -y ce_test_drush_command'
+     And I run 'drush config-enforce:enforce'
+    Then I should get:
+     """
+     Config Enforce enforced configs.
+     """
+     And I am on the homepage
+    Then I should see "Config Enforce Devel -- Test for Drush"
+     And I should see "Drush command appears to work!"