Fix a type error that occurs comparing two large maps with `deepEqual…

…s`. (#2442)

Closes #2442

Avoid inference forcing a `List<Iterable<String>>` which
results in a type error inserting a range into a list requiring
`List<String>`. Add a test for collection truncating which
would have failed with a type error before this fix.

pkgs/checks/CHANGELOG.md

@@ -8,6 +8,8 @@
 -   Add `containsMatchingInOrder` and `containsEqualInOrder` to replace the
     combined functionality in `containsInOrder`.
 -   Replace `pairwiseComparesTo` with `pairwiseMatches`.
+-   Fix a bug where printing the result of a failed deep quality check would
+    fail with a `TypeError` when comparing large `Map` instances 
 -   Increase SDK constraint to ^3.5.0.
 
 ## 0.3.0

pkgs/checks/lib/src/describe.dart

@@ -72,9 +72,10 @@ Iterable<String> _prettyPrint(
 Iterable<String> _prettyPrintCollection(
     String open, String close, List<Iterable<String>> elements, int maxLength) {
   if (elements.length > _maxItems) {
-    elements.replaceRange(_maxItems - 1, elements.length, [
+    const ellipsisElement = [
       ['...']
-    ]);
+    ];
+    elements.replaceRange(_maxItems - 1, elements.length, ellipsisElement);
   }
   if (elements.every((e) => e.length == 1)) {
     final singleLine = '$open${elements.map((e) => e.single).join(', ')}$close';

pkgs/checks/test/pretty_print_test.dart

@@ -0,0 +1,30 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:checks/checks.dart';
+import 'package:checks/context.dart';
+import 'package:test/scaffolding.dart';
+
+void main() {
+  group('literal', () {
+    group('truncates large collections', () {
+      const maxUntruncatedCollection = 25;
+      final largeList =
+          List<int>.generate(maxUntruncatedCollection + 1, (i) => i);
+      test('in lists', () {
+        check(literal(largeList)).last.equals('...]');
+      });
+      test('in sets', () {
+        check(literal(largeList.toSet())).last.equals('...}');
+      });
+      test('in iterables', () {
+        check(literal(largeList.followedBy([]))).last.equals('...)');
+      });
+      test('in maps', () {
+        final map = Map<int, int>.fromIterables(largeList, largeList);
+        check(literal(map)).last.equals('...}');
+      });
+    });
+  });
+}