Add support for explicit preview_path when generating component

docs/CHANGELOG.md

@@ -10,6 +10,10 @@ nav_order: 5
 
 ## main
 
+* Add ability to pass explicit `preview_path` to preview generator.
+
+    *Erinna Chen*
+
 * Add `with_rendered_component_path` helper for writing component system tests.
 
     *Edwin Mak*

lib/rails/generators/preview/component_generator.rb

@@ -4,15 +4,22 @@ module Preview
   module Generators
     class ComponentGenerator < ::Rails::Generators::NamedBase
       source_root File.expand_path("templates", __dir__)
+      class_option :preview_path, type: :string, desc: "Path for previews, required when multiple preview paths are configured", default: ViewComponent::Base.config.generate.preview_path
 
       argument :attributes, type: :array, default: [], banner: "attribute"
       check_class_collision suffix: "ComponentPreview"
 
       def create_preview_file
         preview_paths = ViewComponent::Base.config.preview_paths
-        return if preview_paths.count > 1
+        optional_path = options[:preview_path]
+        return if preview_paths.count > 1 && optional_path.blank?
+
+        path_prefix = if optional_path.present?
+          optional_path
+        else
+          preview_paths.one? ? preview_paths.first : "test/components/previews"
+        end
 
-        path_prefix = preview_paths.one? ? preview_paths.first : "test/components/previews"
         template "component_preview.rb", File.join(path_prefix, class_path, "#{file_name}_component_preview.rb")
       end
 

lib/view_component/config.rb

@@ -12,7 +12,7 @@ class << self
 
       def defaults
         ActiveSupport::OrderedOptions.new.merge!({
-          generate: ActiveSupport::OrderedOptions.new(false),
+          generate: default_generate_options,
           preview_controller: "ViewComponentsController",
           preview_route: "/rails/view_components",
           show_previews_source: false,
@@ -66,6 +66,17 @@ def defaults
       # Always generate a preview alongside the component:
       #
       #      config.view_component.generate.preview = true
+      #
+      # #### #preview_path
+      #
+      # Path to generate preview:
+      #
+      #      config.view_component.generate.preview_path = "test/components/previews"
+      #
+      # Required when there is more than one path defined in preview_paths.
+      # Defaults to `""`. If this is blank, the generator will use
+      # `ViewComponent.config.preview_paths` if defined,
+      # `"test/components/previews"` otherwise
 
       # @!attribute preview_controller
       # @return [String]
@@ -135,6 +146,12 @@ def default_preview_paths
 
         ["#{Rails.root}/test/components/previews"]
       end
+
+      def default_generate_options
+        options = ActiveSupport::OrderedOptions.new(false)
+        options.preview_path = ""
+        options
+      end
     end
 
     def initialize

test/sandbox/test/config_test.rb

@@ -9,7 +9,7 @@ def setup
     end
 
     def test_defaults_are_correct
-      assert_equal @config.generate, {}
+      assert_equal @config.generate, {preview_path: ""}
       assert_equal @config.preview_controller, "ViewComponentsController"
       assert_equal @config.preview_route, "/rails/view_components"
       assert_equal @config.show_previews_source, false

test/sandbox/test/generators/preview_generator_test.rb

@@ -21,6 +21,17 @@ def test_component_preview
     end
   end
 
+  def test_component_preview_with_preview_path_option
+    with_preview_paths([]) do
+      run_generator %w[user --preview --preview-path other/test/components/previews]
+
+      assert_file "other/test/components/previews/user_component_preview.rb" do |component|
+        assert_match(/class UserComponentPreview < /, component)
+        assert_match(/render\(UserComponent.new\)/, component)
+      end
+    end
+  end
+
   def test_component_preview_with_one_overridden_preview_path
     with_preview_paths(%w[spec/components/previews]) do
       run_generator %w[user --preview]
@@ -42,6 +53,17 @@ def test_component_preview_with_two_overridden_preview_paths
     end
   end
 
+  def test_component_preview_with_two_overridden_preview_paths_and_preview_path_option
+    with_preview_paths(%w[spec/components/previews some/other/directory]) do
+      run_generator %w[user --preview --preview-path other/test/components/previews]
+
+      assert_file "other/test/components/previews/user_component_preview.rb" do |component|
+        assert_match(/class UserComponentPreview < /, component)
+        assert_match(/render\(UserComponent.new\)/, component)
+      end
+    end
+  end
+
   def test_component_preview_with_namespace
     with_preview_paths([]) do
       run_generator %w[admins/user --preview]