The `flutter_test` package and `flutter` tool will no longer use the `webGoldenComparator` top-level variable, and instead use the original `goldenFileComparator` top-level variable (like the non-web platforms).
- Who is affected
- Code that still calls the deprecated API; it keeps working until removal but produces analyzer warnings. Code that uses WebGoldenComparator, GoldenFileComparator.
- Practical impact
- Warnings now; removal in a future release. Plan the migration but no immediate break.
- What action should I take?
- Follow the official migration guide below, update affected call sites, run `dart fix --apply` where a fix is available, then run your tests.
Official migration guide (excerpt, © The Flutter Authors, CC BY 3.0)
For most users, no changes are required (other than migrating off the HTML
backend, which is not covered here), the flutter tool will automatically
configure [goldenFileComparator][] and use it (when using a non-HTML web
backend).
For users that implement a custom [WebGoldenComparator][], you will
migrate the implementation to [GoldenFileComparator][]. Fortunately the
Canvas Kit and SkWasm backends already required similar methods (compareButes
and updateBytes).
For example:
// Before
class MyWebGoldenComparator extends WebGoldenComparator {
@override
Future<bool> compare(double width, double height, Uri golden) {
// will be removed in the migration
}
@override
Future<bool> update(double width, double height, Uri golden) {
// will be removed in the migration
}
@override
Future<bool> compareBytes(Uint8List bytes, Uri golden) {
// will be renamed "compare"
}
@override
Future<bool> updateBytes(Uint8List bytes, Uri golden) {
// will be renamed "update" and the parameter orders swapped
}
}
// After
class MyGenericGoldenComparator extends GoldenFileComparator {
@override
Future<bool> compare(Uint8List bytes, Uri golden) {
// used to be "compareBytes"
}
@override
Future<bool> update(Uri golden, Uint8List bytes) {
// used to be "updateBytes"
}
}AI_PROVIDER (for example to openai-compatible with a local Ollama or LM Studio endpoint) to enable grounded explanations. Everything else on this page works without an AI provider.Listed in the official breaking-changes index; title states deprecation.
An official announcement or migration guide documents an intended behaviour or API change. A verified source change (git diff) shows code changed but does not by itself prove a public API is breaking. AI interpretations are labelled and never used to classify a change.
- Source commit
- b3045439b7c0
- Source last updated
- Oct 21, 2026
- Last synchronized
- Oct 21, 2026
- Publication status
- published
Publication history
- Oct 21, 2026, 8:31 PM: new → published (ingestion) — Backed by an official breaking-change/migration guide.
AI_PROVIDER (for example to openai-compatible with a local Ollama or LM Studio endpoint) to enable grounded explanations. Everything else on this page works without an AI provider.