Skip before_render when render? returns false

docs/guide/lifecycle.md

@@ -13,6 +13,8 @@ Since 2.8.0
 
 Define a `before_render` method to be called before a component is rendered, when `helpers` is able to be used:
 
+`before_render` is only called if `render?` returns true. Since `render?` runs first, it must not depend on state set in `before_render`.
+
 ```ruby
 # app/components/example_component.rb
 class ExampleComponent < ViewComponent::Base

lib/view_component/base.rb

@@ -139,9 +139,9 @@ def render_in(view_context, **, &block)
       @__vc_render_in_block = block
       @view_context.instance_variable_set(:@virtual_path, virtual_path)
 
-      before_render
-
       if render?
+        before_render
+
         value = nil
 
         @output_buffer.with_buffer do
@@ -239,6 +239,7 @@ def output_postamble
 
     # Called before rendering the component. Override to perform operations that
     # depend on having access to the view context, such as helpers.
+    # Only called if `render?` returns true.
     #
     # @return [void]
     def before_render

test/sandbox/test/rendering_test.rb

@@ -423,6 +423,33 @@ def test_conditional_rendering
     assert_no_text("component was rendered")
   end
 
+  def test_before_render_is_not_called_when_render_is_false
+    component = ConditionalRenderComponent.new(should_render: false)
+    callbacks = []
+    component.define_singleton_method(:before_render) { callbacks << :before_render }
+
+    render_inline(component)
+
+    assert_empty callbacks
+    refute_component_rendered
+    assert_predicate rendered_content, :html_safe?
+  end
+
+  def test_before_render_is_called_after_render_predicate
+    component = ConditionalRenderComponent.new(should_render: true)
+    callbacks = []
+    component.define_singleton_method(:render?) do
+      callbacks << :render?
+      super()
+    end
+    component.define_singleton_method(:before_render) { callbacks << :before_render }
+
+    render_inline(component)
+
+    assert_equal [:render?, :before_render], callbacks
+    assert_text("component was rendered")
+  end
+
   def test_conditional_rendering_if_content_provided
     render_inline(ConditionalContentComponent.new)