diff --git a/pkg/analyzer_testing/api.txt b/pkg/analyzer_testing/api.txt
index 986b25be1cc..31c0b77dff7 100644
--- a/pkg/analyzer_testing/api.txt
+++ b/pkg/analyzer_testing/api.txt
@@ -5,8 +5,10 @@ package:analyzer_testing/analysis_rule/analysis_rule.dart:
     analysisRule (getter: String)
     assertNoPubspecDiagnostics (method: Future<void> Function(String))
     assertPubspecDiagnostics (method: Future<void> Function(String, List<ExpectedDiagnostic>))
+    correctionMessage (method: String Function(List<Diagnostic>))
     lint (method: ExpectedDiagnostic Function(int, int, {Pattern? correctionContains, Pattern? messageContains, String? name}))
     setUp (method: void Function())
+    unexpectedMessage (method: String Function(List<Diagnostic>))
 package:analyzer_testing/experiments/experiments.dart:
   experimentsForTests (static getter: List<String>)
   experimentsForTests= (static setter: List<String>)
@@ -78,6 +80,8 @@ dart:core:
   int (referenced)
 package:_fe_analyzer_shared/src/base/errors.dart:
   DiagnosticCode (referenced)
+package:analyzer/diagnostic/diagnostic.dart:
+  Diagnostic (referenced)
 package:analyzer/file_system/file_system.dart:
   File (referenced)
   Folder (referenced)
diff --git a/pkg/analyzer_testing/lib/analysis_rule/analysis_rule.dart b/pkg/analyzer_testing/lib/analysis_rule/analysis_rule.dart
index ca278f42960..3626b438342 100644
--- a/pkg/analyzer_testing/lib/analysis_rule/analysis_rule.dart
+++ b/pkg/analyzer_testing/lib/analysis_rule/analysis_rule.dart
@@ -2,6 +2,8 @@
 // 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 'dart:convert' show json;
+
 import 'package:analyzer/analysis_rule/pubspec.dart';
 import 'package:analyzer/diagnostic/diagnostic.dart';
 import 'package:analyzer/error/error.dart';
@@ -46,6 +48,28 @@ abstract class AnalysisRuleTest extends PubPackageResolutionTest {
     assertDiagnosticsIn(errors, expectedDiagnostics);
   }
 
+  @override
+  String correctionMessage(List<Diagnostic> diagnostics) {
+    var buffer = StringBuffer();
+    diagnostics.sort((first, second) => first.offset.compareTo(second.offset));
+    buffer.writeln();
+    buffer.writeln('To accept the current state, expect:');
+    for (var actual in diagnostics) {
+      if (actual.diagnosticCode is LintCode) {
+        buffer.write('  lint(');
+      } else {
+        buffer.write('  error(${actual.diagnosticCode}, ');
+      }
+      buffer.write('${actual.offset}, ${actual.length}');
+      if (actual.diagnosticCode.name != analysisRule) {
+        buffer.write(", name: '${actual.diagnosticCode.name}'");
+      }
+      buffer.writeln('),');
+    }
+
+    return buffer.toString();
+  }
+
   /// Returns an "expected diagnostic" for [analysisRule] (or [name], if given)
   /// at [offset] and [length].
   ///
@@ -79,6 +103,25 @@ abstract class AnalysisRuleTest extends PubPackageResolutionTest {
     );
   }
 
+  @override
+  String unexpectedMessage(List<Diagnostic> unmatchedActual) {
+    var buffer = StringBuffer();
+    if (buffer.isNotEmpty) {
+      buffer.writeln();
+    }
+    buffer.writeln('Found but did not expect:');
+    for (var actual in unmatchedActual) {
+      buffer.write('  $analysisRule.${actual.diagnosticCode.name} [');
+      buffer.write('${actual.offset}, ${actual.length}, ${actual.message}');
+      if (actual.correctionMessage case Pattern correctionMessage) {
+        buffer.write(', ');
+        buffer.write(json.encode(correctionMessage));
+      }
+      buffer.writeln(']');
+    }
+    return buffer.toString();
+  }
+
   Future<List<Diagnostic>> _analyzePubspecFile(String content) async {
     var path = convertPath(testPackagePubspecPath);
     var pubspecRules = <AbstractAnalysisRule, PubspecVisitor<Object?>>{};
diff --git a/pkg/analyzer_testing/lib/src/analysis_rule/pub_package_resolution.dart b/pkg/analyzer_testing/lib/src/analysis_rule/pub_package_resolution.dart
index 6c60548fd8d..4e07710b53b 100644
--- a/pkg/analyzer_testing/lib/src/analysis_rule/pub_package_resolution.dart
+++ b/pkg/analyzer_testing/lib/src/analysis_rule/pub_package_resolution.dart
@@ -212,9 +212,7 @@ class PubPackageResolutionTest with MockPackagesMixin, ResourceProviderMixin {
     List<Diagnostic> diagnostics,
     List<ExpectedDiagnostic> expectedDiagnostics,
   ) {
-    //
     // Match actual diagnostics to expected diagnostics.
-    //
     var unmatchedActual = diagnostics.toList();
     var unmatchedExpected = expectedDiagnostics.toList();
     var actualIndex = 0;
@@ -236,99 +234,33 @@ class PubPackageResolutionTest with MockPackagesMixin, ResourceProviderMixin {
         actualIndex++;
       }
     }
-    //
-    // Write the results.
-    //
+
+    // Print the results to the terminal.
     var buffer = StringBuffer();
     if (unmatchedExpected.isNotEmpty) {
-      buffer.writeln('Expected but did not find:');
-      for (var expected in unmatchedExpected) {
-        buffer.write('  ');
-        if (expected is ExpectedError) {
-          buffer.write(expected._code);
-        }
-        if (expected is ExpectedLint) {
-          buffer.write(expected._lintName);
-        }
-        buffer.write(' [');
-        buffer.write(expected._offset);
-        buffer.write(', ');
-        buffer.write(expected._length);
-        if (expected._messageContains != null) {
-          buffer.write(', messageContains: ');
-          buffer.write(json.encode(expected._messageContains.toString()));
-        }
-        if (expected._correctionContains != null) {
-          buffer.write(', correctionContains: ');
-          buffer.write(json.encode(expected._correctionContains.toString()));
-        }
-        buffer.writeln(']');
-      }
+      buffer.write(missingExpectedMessage(unmatchedExpected));
     }
     if (unmatchedActual.isNotEmpty) {
-      if (buffer.isNotEmpty) {
-        buffer.writeln();
-      }
-      buffer.writeln('Found but did not expect:');
-      for (var actual in unmatchedActual) {
-        buffer.write('  ');
-        buffer.write(actual.diagnosticCode);
-        buffer.write(' [');
-        buffer.write(actual.offset);
-        buffer.write(', ');
-        buffer.write(actual.length);
-        buffer.write(', ');
-        buffer.write(actual.message);
-        if (actual.correctionMessage != null) {
-          buffer.write(', ');
-          buffer.write(json.encode(actual.correctionMessage));
-        }
-        buffer.writeln(']');
-      }
+      buffer.write(unexpectedMessage(unmatchedActual));
     }
-    if (buffer.isNotEmpty) {
-      diagnostics.sort(
-        (first, second) => first.offset.compareTo(second.offset),
-      );
-      buffer.writeln();
-      buffer.writeln('To accept the current state, expect:');
-      for (var actual in diagnostics) {
-        late String diagnosticKind;
-        Object? description;
-        if (actual.diagnosticCode is LintCode) {
-          diagnosticKind = 'lint';
-        } else {
-          diagnosticKind = 'error';
-          description = actual.diagnosticCode;
-        }
-        buffer.write('  $diagnosticKind(');
-        if (description != null) {
-          buffer.write(description);
-          buffer.write(', ');
-        }
-        buffer.write(actual.offset);
-        buffer.write(', ');
-        buffer.write(actual.length);
-        buffer.writeln('),');
-      }
+    if (unmatchedExpected.isNotEmpty || unmatchedActual.isNotEmpty) {
+      buffer.write(correctionMessage(diagnostics));
 
       if (dumpAstOnFailures) {
         buffer.writeln();
         buffer.writeln();
-        try {
-          var astSink = StringBuffer();
 
+        try {
           Spelunker(
             result.unit.toSource(),
-            sink: astSink,
+            sink: buffer,
             featureSet: result.unit.featureSet,
           ).spelunk();
-          buffer.write(astSink);
-          buffer.writeln();
-          // I hereby choose to catch this type.
         } on ArgumentError catch (_) {
           // Perhaps we encountered a parsing error while spelunking.
         }
+
+        buffer.writeln();
       }
 
       fail(buffer.toString());
@@ -371,6 +303,54 @@ class PubPackageResolutionTest with MockPackagesMixin, ResourceProviderMixin {
   Future<void> assertNoDiagnosticsInFile(String path) async =>
       assertDiagnosticsInFile(path, const []);
 
+  /// Text to display upon failure, which indicates possible corrections.
+  @visibleForOverriding
+  String correctionMessage(List<Diagnostic> diagnostics) {
+    var buffer = StringBuffer();
+    diagnostics.sort((first, second) => first.offset.compareTo(second.offset));
+    buffer.writeln();
+    buffer.writeln('To accept the current state, expect:');
+    for (var actual in diagnostics) {
+      if (actual.diagnosticCode is LintCode) {
+        buffer.write('  lint(');
+      } else {
+        buffer.write('  error(${actual.diagnosticCode}, ');
+      }
+      buffer.write('${actual.offset}, ${actual.length}),');
+    }
+
+    return buffer.toString();
+  }
+
+  /// Text to display upon failure, indicating that [unmatchedExpected]
+  /// diagnostics were expected, but not found.
+  @visibleForOverriding
+  String missingExpectedMessage(List<ExpectedDiagnostic> unmatchedExpected) {
+    var buffer = StringBuffer();
+    buffer.writeln('Expected but did not find:');
+    for (var expected in unmatchedExpected) {
+      buffer.write('  ');
+      if (expected is ExpectedError) {
+        buffer.write(expected._code);
+      }
+      if (expected is ExpectedLint) {
+        buffer.write(expected._lintName);
+      }
+      buffer.write(' [${expected._offset}, ');
+      buffer.write(expected._length);
+      if (expected._messageContains case Pattern messageContains) {
+        buffer.write(', messageContains: ');
+        buffer.write(json.encode(messageContains.toString()));
+      }
+      if (expected._correctionContains case Pattern correctionContains) {
+        buffer.write(', correctionContains: ');
+        buffer.write(json.encode(correctionContains.toString()));
+      }
+      buffer.writeln(']');
+    }
+    return buffer.toString();
+  }
+
   @override
   File newFile(String path, String content) {
     if (_analysisContextCollection != null && !path.endsWith('.dart')) {
@@ -414,6 +394,27 @@ class PubPackageResolutionTest with MockPackagesMixin, ResourceProviderMixin {
     _analysisContextCollection = null;
   }
 
+  /// Text to display upon failure, indicating that [unmatchedActual]
+  /// diagnostics were found, but unexpected.
+  @visibleForOverriding
+  String unexpectedMessage(List<Diagnostic> unmatchedActual) {
+    var buffer = StringBuffer();
+    if (buffer.isNotEmpty) {
+      buffer.writeln();
+    }
+    buffer.writeln('Found but did not expect:');
+    for (var actual in unmatchedActual) {
+      buffer.write('  ${actual.diagnosticCode} [');
+      buffer.write('${actual.offset}, ${actual.length}, ${actual.message}');
+      if (actual.correctionMessage case Pattern correctionMessage) {
+        buffer.write(', ');
+        buffer.write(json.encode(correctionMessage));
+      }
+      buffer.writeln(']');
+    }
+    return buffer.toString();
+  }
+
   void writePackageConfig(String path, PackageConfigFileBuilder config) {
     newFile(path, config.toContent(pathContext: pathContext));
   }