[CI] remove check for exact golden files. (#166031)

Instead make sure at least 1 png is generated.

---------

Co-authored-by: Matan Lurey <matanlurey@users.noreply.github.com>

Author: Jonah Williams

engine/src/flutter/CONTRIBUTING.md

@@ -59,7 +59,7 @@ performance implications. See [#49801][pr_49801] for an example.
 
 #### Linux Embedding
 
-> [!NOTE]  
+> [!NOTE]
 > The Linux embedding instead follows idiomatic GObject-based C style.
 
 Use of C++ in the [Linux embedding][] is discouraged in that embedding to avoid
@@ -215,14 +215,10 @@ in postsubmit.
 
 ### Skia Gold
 
-The Flutter engine uses [Skia Gold][skia_gold] for image comparison tests which fail if:
-
-- The image is different from an accepted baseline.
-- An image is not uploaded but is expected to be (see
-  [`dir_contents_diff`][dir_contents_diff]).
+The Flutter engine uses [Skia Gold][skia_gold] for image comparison tests which
+fail if the image is different from an accepted baseline image.
 
 [skia_gold]: https://flutter-engine-gold.skia.org/
-[dir_contents_diff]: ./tools/dir_contents_diff/
 
 Any untriaged failures will block presubmit and postsubmit tests.
 

engine/src/flutter/impeller/display_list/aiks_dl_atlas_unittests.cc

@@ -176,7 +176,7 @@ TEST_P(AiksTest, DrawAtlasPlusWideGamut) {
   ASSERT_TRUE(OpenPlaygroundHere(builder.Build()));
 }
 
-TEST_P(AiksTest, DlAtlasGeometryNoBlend) {
+TEST_P(AiksTest, DlAtlasGeometryNoBlendRenamed) {
   auto [texture_coordinates, transforms, atlas] = CreateTestData(this);
 
   DlAtlasGeometry geom(atlas->impeller_texture(), transforms.data(),

engine/src/flutter/pubspec.yaml

@@ -97,7 +97,6 @@ workspace:
   - tools/clangd_check
   - tools/compare_goldens
   - tools/const_finder
-  - tools/dir_contents_diff
   - tools/engine_tool
   - tools/header_guard_check
   - tools/gen_web_locale_keymap

engine/src/flutter/testing/impeller_golden_tests_output.txt

@@ -14,7 +14,6 @@ resolution: workspace
 
 dependencies:
   args: any
-  dir_contents_diff: any
   engine_repo_tools: any
   meta: any
   path: any

engine/src/flutter/testing/ios_scenario_app/pubspec.yaml

@@ -968,7 +968,6 @@ def build_dart_host_test_list():
       os.path.join('flutter', 'tools', 'build_bucket_golden_scraper'),
       os.path.join('flutter', 'tools', 'clang_tidy'),
       os.path.join('flutter', 'tools', 'const_finder'),
-      os.path.join('flutter', 'tools', 'dir_contents_diff'),
       os.path.join('flutter', 'tools', 'engine_tool'),
       os.path.join('flutter', 'tools', 'githooks'),
       os.path.join('flutter', 'tools', 'header_guard_check'),
@@ -1061,6 +1060,23 @@ def __exit__(self, exception_type, exception_value, exception_traceback):
     os.chdir(self.old_cwd)
 
 
+def contains_png_recursive(directory):
+  """
+  Recursively checks if a directory contains at least one .png file.
+
+  Args:
+    directory: The path to the directory to check.
+
+  Returns:
+    True if a .png file is found, False otherwise.
+  """
+  for _, _, files in os.walk(directory):
+    for filename in files:
+      if filename.lower().endswith('.png'):
+        return True
+  return False
+
+
 def run_impeller_golden_tests(build_dir: str, require_skia_gold: bool = False):
   """
   Executes the impeller golden image tests from in the `variant` build.
@@ -1079,19 +1095,9 @@ def run_impeller_golden_tests(build_dir: str, require_skia_gold: bool = False):
     extra_env.update(vulkan_validation_env(build_dir))
     run_cmd([tests_path, f'--working_dir={temp_dir}'], cwd=build_dir, env=extra_env)
     dart_bin = os.path.join(build_dir, 'dart-sdk', 'bin', 'dart')
-    golden_path = os.path.join('testing', 'impeller_golden_tests_output.txt')
-    script_path = os.path.join('tools', 'dir_contents_diff', 'bin', 'dir_contents_diff.dart')
-    diff_result = subprocess.run(
-        f'{dart_bin} {script_path} {golden_path} {temp_dir}',
-        check=False,
-        shell=True,
-        stdout=subprocess.PIPE,
-        cwd=os.path.join(BUILDROOT_DIR, 'flutter')
-    )
-    if diff_result.returncode != 0:
-      print_divider('<')
-      print(diff_result.stdout.decode())
-      raise RuntimeError('impeller_golden_tests diff failure')
+
+    if not contains_png_recursive(temp_dir):
+      raise RuntimeError('impeller_golden_tests diff failure - no PNGs found!')
 
     if not require_skia_gold:
       print_divider('<')