[Impeller] add example of testing entity with "real" HAL instead of mocking. (#47631)

As a response to my comments in #47621

Author: Jonah Williams

ci/licenses_golden/excluded_files

@@ -134,6 +134,7 @@
 ../../../flutter/impeller/display_list/dl_unittests.cc
 ../../../flutter/impeller/display_list/skia_conversions_unittests.cc
 ../../../flutter/impeller/docs
+../../../flutter/impeller/entity/contents/checkerboard_contents_unittests.cc
 ../../../flutter/impeller/entity/contents/filters/inputs/filter_input_unittests.cc
 ../../../flutter/impeller/entity/entity_unittests.cc
 ../../../flutter/impeller/entity/geometry/geometry_unittests.cc

impeller/entity/BUILD.gn

@@ -268,6 +268,7 @@ impeller_component("entity_unittests") {
   testonly = true
 
   sources = [
+    "contents/checkerboard_contents_unittests.cc",
     "contents/filters/inputs/filter_input_unittests.cc",
     "entity_playground.cc",
     "entity_playground.h",

impeller/entity/contents/checkerboard_contents.h

@@ -4,7 +4,6 @@
 
 #pragma once
 
-#include "flutter/fml/macros.h"
 #include "impeller/entity/contents/contents.h"
 
 namespace impeller {

impeller/entity/contents/checkerboard_contents_unittests.cc

@@ -0,0 +1,50 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <memory>
+#include <optional>
+
+#include "gtest/gtest.h"
+
+#include "impeller/entity/contents/checkerboard_contents.h"
+#include "impeller/entity/contents/contents.h"
+#include "impeller/entity/entity.h"
+#include "impeller/entity/entity_playground.h"
+#include "impeller/renderer/render_target.h"
+
+namespace impeller {
+namespace testing {
+
+using EntityTest = EntityPlayground;
+INSTANTIATE_PLAYGROUND_SUITE(EntityTest);
+
+#ifdef IMPELLER_DEBUG
+TEST(EntityTest, HasNulloptCoverage) {
+  auto contents = std::make_shared<CheckerboardContents>();
+
+  Entity entity;
+  ASSERT_EQ(contents->GetCoverage(entity), std::nullopt);
+}
+
+TEST_P(EntityTest, RendersWithoutError) {
+  auto contents = std::make_shared<CheckerboardContents>();
+  contents->SetColor(Color::Aqua());
+  contents->SetSquareSize(10);
+
+  auto content_context = GetContentContext();
+  auto buffer = content_context->GetContext()->CreateCommandBuffer();
+  auto render_target = RenderTarget::CreateOffscreenMSAA(
+      *content_context->GetContext(),
+      *GetContentContext()->GetRenderTargetCache(), {100, 100});
+  auto render_pass = buffer->CreateRenderPass(render_target);
+  Entity entity;
+
+  ASSERT_TRUE(render_pass->GetCommands().empty());
+  ASSERT_TRUE(contents->Render(*content_context, entity, *render_pass));
+  ASSERT_FALSE(render_pass->GetCommands().empty());
+}
+#endif  // IMPELLER_DEBUG
+
+}  // namespace testing
+}  // namespace impeller

impeller/entity/entity_playground.cc

@@ -36,17 +36,21 @@ bool EntityPlayground::OpenPlaygroundHere(EntityPass& entity_pass) {
   return Playground::OpenPlaygroundHere(callback);
 }
 
+std::shared_ptr<ContentContext> EntityPlayground::GetContentContext() const {
+  return std::make_shared<ContentContext>(GetContext(), typographer_context_);
+}
+
 bool EntityPlayground::OpenPlaygroundHere(Entity entity) {
   if (!switches_.enable_playground) {
     return true;
   }
 
-  ContentContext content_context(GetContext(), typographer_context_);
-  if (!content_context.IsValid()) {
+  auto content_context = GetContentContext();
+  if (!content_context->IsValid()) {
     return false;
   }
   SinglePassCallback callback = [&](RenderPass& pass) -> bool {
-    return entity.Render(content_context, pass);
+    return entity.Render(*content_context, pass);
   };
   return Playground::OpenPlaygroundHere(callback);
 }

impeller/entity/entity_playground.h

@@ -32,6 +32,8 @@ class EntityPlayground : public PlaygroundTest {
 
   bool OpenPlaygroundHere(EntityPlaygroundCallback callback);
 
+  std::shared_ptr<ContentContext> GetContentContext() const;
+
  private:
   std::shared_ptr<TypographerContext> typographer_context_;
 

impeller/entity/entity_unittests.cc

@@ -2,24 +2,19 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include <algorithm>
 #include <cstring>
 #include <memory>
 #include <optional>
-#include <unordered_map>
 #include <utility>
 #include <vector>
 
-#include "flutter/testing/testing.h"
 #include "fml/logging.h"
-#include "fml/time/time_point.h"
 #include "gtest/gtest.h"
 #include "impeller/core/texture_descriptor.h"
 #include "impeller/entity/contents/atlas_contents.h"
 #include "impeller/entity/contents/clip_contents.h"
 #include "impeller/entity/contents/conical_gradient_contents.h"
 #include "impeller/entity/contents/contents.h"
-#include "impeller/entity/contents/filters/blend_filter_contents.h"
 #include "impeller/entity/contents/filters/color_filter_contents.h"
 #include "impeller/entity/contents/filters/filter_contents.h"
 #include "impeller/entity/contents/filters/inputs/filter_input.h"
@@ -28,11 +23,9 @@
 #include "impeller/entity/contents/runtime_effect_contents.h"
 #include "impeller/entity/contents/solid_color_contents.h"
 #include "impeller/entity/contents/solid_rrect_blur_contents.h"
-#include "impeller/entity/contents/sweep_gradient_contents.h"
 #include "impeller/entity/contents/text_contents.h"
 #include "impeller/entity/contents/texture_contents.h"
 #include "impeller/entity/contents/tiled_texture_contents.h"
-#include "impeller/entity/contents/vertices_contents.h"
 #include "impeller/entity/entity.h"
 #include "impeller/entity/entity_pass.h"
 #include "impeller/entity/entity_pass_delegate.h"
@@ -50,11 +43,8 @@
 #include "impeller/renderer/command.h"
 #include "impeller/renderer/render_pass.h"
 #include "impeller/renderer/vertex_buffer_builder.h"
-#include "impeller/runtime_stage/runtime_stage.h"
-#include "impeller/tessellator/tessellator.h"
 #include "impeller/typographer/backends/skia/text_frame_skia.h"
 #include "impeller/typographer/backends/skia/typographer_context_skia.h"
-#include "include/core/SkBlendMode.h"
 #include "third_party/imgui/imgui.h"
 #include "third_party/skia/include/core/SkTextBlob.h"