From 6cfa97f21c893408dd686b1f83be21bb43d07393 Mon Sep 17 00:00:00 2001
From: Nate Bosch <nbosch@google.com>
Date: Thu, 18 Sep 2025 20:13:18 +0000
Subject: [PATCH] Allow exceptions from operator ==

It's confusing to treat an object that throws from `operator ==`
identically to one that returns `false` normally. Intentional exceptions
in `operator ==` are very unlikely, so this change is not likely to
cause spurious failures.
---
 pkgs/matcher/CHANGELOG.md                |  2 ++
 pkgs/matcher/lib/src/equals_matcher.dart | 22 ++++++----------------
 2 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/pkgs/matcher/CHANGELOG.md b/pkgs/matcher/CHANGELOG.md
index dfb0c9ef0..08eee404f 100644
--- a/pkgs/matcher/CHANGELOG.md
+++ b/pkgs/matcher/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 * Add `isSorted` and related matchers for iterables.
 * Consider `NaN` to be equal to itself in `equals`.
+* Allow exceptions from `operator ==` to bubble up and fail the test instead of
+  treating them as unequal objects.
 * Remove some dynamic invocations.
 * Add explicit casts from `dynamic` values.
 * Require Dart 3.7
diff --git a/pkgs/matcher/lib/src/equals_matcher.dart b/pkgs/matcher/lib/src/equals_matcher.dart
index d1f5d39ad..695b13d88 100644
--- a/pkgs/matcher/lib/src/equals_matcher.dart
+++ b/pkgs/matcher/lib/src/equals_matcher.dart
@@ -210,22 +210,12 @@ class _DeepMatcher extends Matcher {
       });
     } else {
       // Otherwise, test for equality, or both values NaN
-      try {
-        if (expected == actual ||
-            (expected is num &&
-                expected.isNaN &&
-                actual is num &&
-                actual.isNaN)) {
-          return null;
-        }
-      } catch (e) {
-        // TODO(gram): Add a test for this case.
-        return _Mismatch(
-          location,
-          actual,
-          (description, verbose) =>
-              description.add('== threw ').addDescriptionOf(e),
-        );
+      if (expected == actual ||
+          (expected is num &&
+              expected.isNaN &&
+              actual is num &&
+              actual.isNaN)) {
+        return null;
       }
     }