From ad180be21200a37ca06b94c1687ec5ea0eb555cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Amaury=20Lev=C3=A9?= <amauryleve@microsoft.com>
Date: Fri, 15 May 2026 16:07:32 +0200
Subject: [PATCH 1/4] Apply structured assertion messages (RFC 012) to
 Assert.HasCount / IsEmpty / IsNotEmpty

Migrates Assert.HasCount, Assert.IsEmpty, and Assert.IsNotEmpty (and their interpolated-string-handler overloads) to the structured assertion message format defined in RFC 012.

The HasCount/IsEmpty evidence block surfaces 'expected count:' and 'actual count:' so the size mismatch is visible at a glance; IsNotEmpty omits the expected line because the only actionable count is the actual zero.

The interpolated-string-handler now passes the user-built message directly to the structured report and lets FormatCallSiteExpression reconstruct the call-site (e.g. Assert.HasCount(1, Array.Empty<int>())) so the literal expected count remains visible even on the interpolated path.

Updates the affected message-format tests in AssertTests.Items.cs to assert against the new layout.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../TestFramework/Assertions/Assert.Count.cs  | 59 ++++++++++--------
 .../Resources/FrameworkMessages.resx          |  9 +++
 .../Resources/xlf/FrameworkMessages.cs.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.de.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.es.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.fr.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.it.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.ja.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.ko.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.pl.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.pt-BR.xlf | 15 +++++
 .../Resources/xlf/FrameworkMessages.ru.xlf    | 15 +++++
 .../Resources/xlf/FrameworkMessages.tr.xlf    | 15 +++++
 .../xlf/FrameworkMessages.zh-Hans.xlf         | 15 +++++
 .../xlf/FrameworkMessages.zh-Hant.xlf         | 15 +++++
 .../Assertions/AssertTests.Items.cs           | 61 +++++++++++++++++--
 16 files changed, 294 insertions(+), 30 deletions(-)

diff --git a/src/TestFramework/TestFramework/Assertions/Assert.Count.cs b/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
index 4ad00d8d02..038dfc3da0 100644
--- a/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
+++ b/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
@@ -47,8 +47,7 @@ internal void ComputeAssertion(string assertionName, string collectionExpression
         {
             if (_builder is not null)
             {
-                _builder.Insert(0, string.Format(CultureInfo.CurrentCulture, FrameworkMessages.CallerArgumentExpressionSingleParameterMessage, "collection", collectionExpression) + " ");
-                ReportAssertCountFailed(assertionName, _expectedCount, _actualCount, _builder.ToString());
+                ReportAssertCountFailed(assertionName, _expectedCount, _actualCount, _builder.ToString(), collectionExpression);
             }
         }
 
@@ -115,8 +114,7 @@ internal void ComputeAssertion(string collectionExpression)
         {
             if (_builder is not null)
             {
-                _builder.Insert(0, string.Format(CultureInfo.CurrentCulture, FrameworkMessages.CallerArgumentExpressionSingleParameterMessage, "collection", collectionExpression) + " ");
-                ReportAssertIsNotEmptyFailed(_builder.ToString());
+                ReportAssertIsNotEmptyFailed(_builder.ToString(), collectionExpression);
             }
         }
 
@@ -202,8 +200,7 @@ public static void IsNotEmpty<T>(IEnumerable<T> collection, string? message = ""
             return;
         }
 
-        string userMessage = BuildUserMessageForCollectionExpression(message, collectionExpression);
-        ReportAssertIsNotEmptyFailed(userMessage);
+        ReportAssertIsNotEmptyFailed(message, collectionExpression);
     }
 
     /// <summary>
@@ -222,8 +219,7 @@ public static void IsNotEmpty(IEnumerable collection, string? message = "", [Cal
             return;
         }
 
-        string userMessage = BuildUserMessageForCollectionExpression(message, collectionExpression);
-        ReportAssertIsNotEmptyFailed(userMessage);
+        ReportAssertIsNotEmptyFailed(message, collectionExpression);
     }
     #endregion // IsNotEmpty
 
@@ -326,32 +322,47 @@ private static void HasCount<T>(string assertionName, int expected, IEnumerable<
             return;
         }
 
-        string userMessage = BuildUserMessageForCollectionExpression(message, collectionExpression);
-        ReportAssertCountFailed(assertionName, expected, actualCount, userMessage);
+        ReportAssertCountFailed(assertionName, expected, actualCount, message, collectionExpression);
     }
 
     private static void HasCount(string assertionName, int expected, IEnumerable collection, string? message, string collectionExpression)
         => HasCount(assertionName, expected, collection.Cast<object>(), message, collectionExpression);
 
     [DoesNotReturn]
-    private static void ReportAssertCountFailed(string assertionName, int expectedCount, int actualCount, string userMessage)
+    private static void ReportAssertCountFailed(string assertionName, int expectedCount, int actualCount, string? userMessage, string collectionExpression)
     {
-        string finalMessage = string.Format(
-            CultureInfo.CurrentCulture,
-            FrameworkMessages.HasCountFailMsg,
-            userMessage,
-            expectedCount,
-            actualCount);
-        ReportAssertFailed($"Assert.{assertionName}", finalMessage);
+        string summary = assertionName == "IsEmpty"
+            ? FrameworkMessages.IsEmptyFailedSummary
+            : FrameworkMessages.HasCountFailedSummary;
+
+        string expectedText = expectedCount.ToString(CultureInfo.CurrentCulture);
+        string actualText = actualCount.ToString(CultureInfo.CurrentCulture);
+        EvidenceBlock evidence = EvidenceBlock.Create()
+            .AddLine("expected count:", expectedText)
+            .AddLine("actual count:", actualText);
+
+        StructuredAssertionMessage structured = new(summary);
+        structured.WithUserMessage(userMessage);
+        structured.WithEvidence(evidence);
+        structured.WithExpectedAndActual(expectedText, actualText);
+        structured.WithCallSiteExpression(assertionName == "IsEmpty"
+            ? FormatCallSiteExpression($"Assert.{assertionName}", collectionExpression, "<collection>")
+            : FormatCallSiteExpression($"Assert.{assertionName}", expectedText, collectionExpression, "<expected>", "<collection>"));
+
+        ReportAssertFailed(structured);
     }
 
     [DoesNotReturn]
-    private static void ReportAssertIsNotEmptyFailed(string userMessage)
+    private static void ReportAssertIsNotEmptyFailed(string? userMessage, string collectionExpression)
     {
-        string finalMessage = string.Format(
-            CultureInfo.CurrentCulture,
-            FrameworkMessages.IsNotEmptyFailMsg,
-            userMessage);
-        ReportAssertFailed("Assert.IsNotEmpty", finalMessage);
+        EvidenceBlock evidence = EvidenceBlock.Create()
+            .AddLine("actual count:", "0");
+
+        StructuredAssertionMessage structured = new(FrameworkMessages.IsNotEmptyFailedSummary);
+        structured.WithUserMessage(userMessage);
+        structured.WithEvidence(evidence);
+        structured.WithCallSiteExpression(FormatCallSiteExpression("Assert.IsNotEmpty", collectionExpression, "<collection>"));
+
+        ReportAssertFailed(structured);
     }
 }
diff --git a/src/TestFramework/TestFramework/Resources/FrameworkMessages.resx b/src/TestFramework/TestFramework/Resources/FrameworkMessages.resx
index 691f3edab7..c75a1ff6b1 100644
--- a/src/TestFramework/TestFramework/Resources/FrameworkMessages.resx
+++ b/src/TestFramework/TestFramework/Resources/FrameworkMessages.resx
@@ -420,4 +420,13 @@ Actual: {2}</value>
   <data name="IsNotNullFailedSummary" xml:space="preserve">
     <value>Expected value to not be null.</value>
   </data>
+  <data name="HasCountFailedSummary" xml:space="preserve">
+    <value>Expected collection to contain a specific number of elements.</value>
+  </data>
+  <data name="IsEmptyFailedSummary" xml:space="preserve">
+    <value>Expected collection to be empty.</value>
+  </data>
+  <data name="IsNotEmptyFailedSummary" xml:space="preserve">
+    <value>Expected collection to not be empty.</value>
+  </data>
 </root>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.cs.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.cs.xlf
index 4ad5deac23..b442c81cc8 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.cs.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.cs.xlf
@@ -262,6 +262,11 @@ Skutečnost: {2}</target>
         <target state="translated">Očekávala se kolekce {1} velikosti. Skutečnost: {2} {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">Vlastnost TestContext.{0} souvisí s aktuálním testem a není k dispozici během sestavení nebo používání testovacích přípravků tříd.</target>
@@ -272,6 +277,11 @@ Skutečnost: {2}</target>
         <target state="translated">Neplatná adresa URL lístku GitHubu</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Skutečnost: {2}</target>
         <target state="translated">Očekávalo se, že kolekce bude obsahovat libovolnou položku, ale je prázdná. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Špatný typ:&lt;{1}&gt;. Aktuální typ:&lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.de.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.de.xlf
index f61ee46c58..c4d9dcc987 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.de.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.de.xlf
@@ -262,6 +262,11 @@ Tatsächlich: {2}</target>
         <target state="translated">Es wurde eine Sammlung mit einer Größe {1} erwartet. Tatsächlich: {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">Die Eigenschaft „TestContext.{0}“ im Zusammenhang mit dem aktuellen Test steht während Assembly- oder Klassenfixierungen nicht zur Verfügung.</target>
@@ -272,6 +277,11 @@ Tatsächlich: {2}</target>
         <target state="translated">Ungültige GitHub-Ticket-URL.</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Tatsächlich: {2}</target>
         <target state="translated">Es wurde erwartet, dass die Sammlung ein beliebiges Element enthält, aber leer ist. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Falscher Typ:&lt;{1}&gt;. Tatsächlicher Typ:&lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.es.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.es.xlf
index 94a5797fc0..3975021539 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.es.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.es.xlf
@@ -262,6 +262,11 @@ Real: {2}</target>
         <target state="translated">Se esperaba una colección de tamaño {1}. Real: {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">La propiedad "TestContext.{0}" está relacionado con la prueba actual y no está disponible durante los accesorios de ensamblado o clase.</target>
@@ -272,6 +277,11 @@ Real: {2}</target>
         <target state="translated">Dirección URL de vale de GitHub no válida</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Real: {2}</target>
         <target state="translated">Se esperaba que la colección contenga cualquier elemento, pero está vacía. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Tipo incorrecto:&lt;{1}&gt;. Tipo actual:&lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.fr.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.fr.xlf
index 00d78302f3..8eb73ed3f6 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.fr.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.fr.xlf
@@ -262,6 +262,11 @@ Réel : {2}</target>
         <target state="translated">Collection de tailles attendue {1}. Réel : {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">La propriété « TestContext.{0} », liée au test en cours, n’est pas disponible pendant les fixtures d’assembly ou de classe.</target>
@@ -272,6 +277,11 @@ Réel : {2}</target>
         <target state="translated">URL de ticket GitHub non valide</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Réel : {2}</target>
         <target state="translated">La collection doit contenir n’importe quel élément, mais elle est vide. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Type incorrect : &lt;{1}&gt;, Type réel : &lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.it.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.it.xlf
index 80b0b1b715..d3ef3d8d30 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.it.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.it.xlf
@@ -262,6 +262,11 @@ Effettivo: {2}</target>
         <target state="translated">Prevista raccolta di dimensioni {1}. Effettivo: {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">La proprietà 'TestContext.{0}' relativa al test corrente non è disponibile durante le fixture di assembly o classe.</target>
@@ -272,6 +277,11 @@ Effettivo: {2}</target>
         <target state="translated">L'URL del ticket GitHub non è valido</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Effettivo: {2}</target>
         <target state="translated">È previsto che la raccolta contenga qualsiasi elemento, ma è vuota. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Tipo errato:&lt;{1}&gt;. Tipo effettivo:&lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ja.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ja.xlf
index ee5344f86b..16d7d5456e 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ja.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ja.xlf
@@ -262,6 +262,11 @@ Actual: {2}</source>
         <target state="translated">サイズ {1} のコレクションが必要です。実際: {2}。{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">プロパティ 'TestContext.{0}' は現在のテストに関連しており、アセンブリまたはクラス フィクスチャの間は使用できません。</target>
@@ -272,6 +277,11 @@ Actual: {2}</source>
         <target state="translated">GitHub チケット URL が無効です</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Actual: {2}</source>
         <target state="translated">コレクションには項目が含まれている必要がありますが、空です。{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">正しくない型は &lt;{1}&gt; であり、実際の型は &lt;{2}&gt; です。{0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ko.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ko.xlf
index e1d64ff123..896c34531f 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ko.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ko.xlf
@@ -262,6 +262,11 @@ Actual: {2}</source>
         <target state="translated">{1} 크기 컬렉션이 필요합니다. 실제: {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">현재 테스트와 관련된 'TestContext.{0}' 속성은 어셈블리나 클래스 픽스처 실행 중에는 사용할 수 없습니다.</target>
@@ -272,6 +277,11 @@ Actual: {2}</source>
         <target state="translated">잘못된 GitHub 티켓 URL</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Actual: {2}</source>
         <target state="translated">항목을 포함할 컬렉션이 필요한데 비어 있습니다. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">잘못된 형식: &lt;{1}&gt;, 실제 형식: &lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.pl.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.pl.xlf
index b09f5eb893..28584660a6 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.pl.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.pl.xlf
@@ -262,6 +262,11 @@ Rzeczywiste: {2}</target>
         <target state="translated">Oczekiwano kolekcji rozmiaru {1}. Wartość rzeczywista: {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">Właściwość „TestContext.{0}” jest powiązana z bieżącym testem i nie jest dostępna podczas montażu lub konfiguracji klasy.</target>
@@ -272,6 +277,11 @@ Rzeczywiste: {2}</target>
         <target state="translated">Nieprawidłowy adres URL biletu usługi GitHub</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Rzeczywiste: {2}</target>
         <target state="translated">Oczekiwano, że kolekcja będzie zawierać dowolny element, ale jest pusta. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Zły typ:&lt;{1}&gt;. Rzeczywisty typ:&lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.pt-BR.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.pt-BR.xlf
index 3fdabfe37d..9e419bacf6 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.pt-BR.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.pt-BR.xlf
@@ -262,6 +262,11 @@ Real: {2}</target>
         <target state="translated">Coleção esperada de tamanho {1}. Real: {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">A propriedade "TestContext.{0}" está relacionada ao teste atual não está disponível durante os acessórios de assembly ou classe.</target>
@@ -272,6 +277,11 @@ Real: {2}</target>
         <target state="translated">URL de tíquete do GitHub inválida</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Real: {2}</target>
         <target state="translated">A coleção esperada conter qualquer item, mas ela está vazia. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Tipo errado:&lt;{1}&gt;. Tipo real:&lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ru.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ru.xlf
index 8262985ee7..77b838ba52 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ru.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.ru.xlf
@@ -262,6 +262,11 @@ Actual: {2}</source>
         <target state="translated">Ожидается коллекция размеров {1}. Фактически: {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">Свойство "TestContext.{0}" связано с текущим тестом и недоступно во время выполнения средств тестирования сборок или классов.</target>
@@ -272,6 +277,11 @@ Actual: {2}</source>
         <target state="translated">Недопустимый URL-адрес билета GitHub</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Actual: {2}</source>
         <target state="translated">Ожидается, что коллекция будет содержать любой элемент, но она пуста. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Неверный тип: &lt;{1}&gt;. Фактический тип: &lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.tr.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.tr.xlf
index 8420e144a3..dd6653dfcc 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.tr.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.tr.xlf
@@ -262,6 +262,11 @@ Gerçekte olan: {2}</target>
         <target state="translated">Beklenen boyut {1}. Gerçek: {2}. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">'TestContext.{0}' özelliği, derleme veya sınıf sabitlemeleri sırasında mevcut testle ilişkili değildir.</target>
@@ -272,6 +277,11 @@ Gerçekte olan: {2}</target>
         <target state="translated">Geçersiz GitHub anahtar URL'si</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Gerçekte olan: {2}</target>
         <target state="translated">Koleksiyonun herhangi bir öğe içermesi bekleniyordu ancak boş. {0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">Yanlış Tür:&lt;{1}&gt;. Gerçek tür:&lt;{2}&gt;. {0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.zh-Hans.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.zh-Hans.xlf
index 0b7558f104..c5664c0cb7 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.zh-Hans.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.zh-Hans.xlf
@@ -262,6 +262,11 @@ Actual: {2}</source>
         <target state="translated">大小 {1} 的预期集合。实际： {2}。{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">属性‘TestContext.{0}’与当前测试相关，在程序集或类固定例程期间不可用。</target>
@@ -272,6 +277,11 @@ Actual: {2}</source>
         <target state="translated">GitHub 票证 URL 无效</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Actual: {2}</source>
         <target state="translated">集合应包含任何项，但它为空。{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">错误类型为: &lt;{1}&gt;，实际类型为: &lt;{2}&gt;。{0}</target>
diff --git a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.zh-Hant.xlf b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.zh-Hant.xlf
index cc658d8057..90d528b024 100644
--- a/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.zh-Hant.xlf
+++ b/src/TestFramework/TestFramework/Resources/xlf/FrameworkMessages.zh-Hant.xlf
@@ -262,6 +262,11 @@ Actual: {2}</source>
         <target state="translated">預期的大小集合 {1}。實際： {2}。{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="HasCountFailedSummary">
+        <source>Expected collection to contain a specific number of elements.</source>
+        <target state="new">Expected collection to contain a specific number of elements.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidAccessToTestContextProperty">
         <source>The property 'TestContext.{0}' is related to current test is not available during assembly or class fixtures.</source>
         <target state="translated">屬性 'TestContext.{0}' 與目前測試相關，無法在組件或類別測試夾具期間使用。</target>
@@ -272,6 +277,11 @@ Actual: {2}</source>
         <target state="translated">無效的 GitHub 票證 URL</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsEmptyFailedSummary">
+        <source>Expected collection to be empty.</source>
+        <target state="new">Expected collection to be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsFalseFailedSummary">
         <source>Expected condition to be false.</source>
         <target state="new">Expected condition to be false.</target>
@@ -302,6 +312,11 @@ Actual: {2}</source>
         <target state="translated">預期集合包含任何專案，但卻是空的。{0}</target>
         <note />
       </trans-unit>
+      <trans-unit id="IsNotEmptyFailedSummary">
+        <source>Expected collection to not be empty.</source>
+        <target state="new">Expected collection to not be empty.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IsNotInstanceOfFailMsg">
         <source>Wrong Type:&lt;{1}&gt;. Actual type:&lt;{2}&gt;. {0}</source>
         <target state="translated">錯誤的類型: &lt;{1}&gt;。實際的類型: &lt;{2}&gt;。{0}</target>
diff --git a/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs b/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
index 98a5160f29..a20a0d5be9 100644
--- a/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
+++ b/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
@@ -25,7 +25,15 @@ public void Count_WhenCountIsNotSame_ShouldFail()
         var collection = new List<int> { 1 };
         Action action = () => Assert.HasCount(3, collection);
         action.Should().Throw<Exception>()
-            .WithMessage("Assert.HasCount failed. Expected collection of size 3. Actual: 1. 'collection' expression: 'collection'.");
+            .WithMessage(
+                """
+                Assertion failed. Expected collection to contain a specific number of elements.
+
+                expected count: 3
+                actual count:   1
+
+                Assert.HasCount(3, collection)
+                """);
     }
 
     public async Task Count_InterpolatedString_WhenCountIsNotSame_ShouldFail()
@@ -34,7 +42,16 @@ public async Task Count_InterpolatedString_WhenCountIsNotSame_ShouldFail()
         DateTime dateTime = DateTime.Now;
         Func<Task> action = async () => Assert.HasCount(1, Array.Empty<int>(), $"User-provided message. {o}, {o,35}, {await GetHelloStringAsync()}, {new DummyIFormattable()}, {dateTime:tt}, {dateTime,5:tt}");
         (await action.Should().ThrowAsync<Exception>())
-            .WithMessage($"Assert.HasCount failed. Expected collection of size 1. Actual: 0. 'collection' expression: 'Array.Empty<int>()'. User-provided message. DummyClassTrackingToStringCalls,     DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {string.Format(null, "{0:tt}", dateTime)}, {string.Format(null, "{0,5:tt}", dateTime)}");
+            .WithMessage(
+                $$"""
+                Assertion failed. Expected collection to contain a specific number of elements.
+                User-provided message. DummyClassTrackingToStringCalls,     DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {{string.Format(null, "{0:tt}", dateTime)}}, {{string.Format(null, "{0,5:tt}", dateTime)}}
+
+                expected count: 1
+                actual count:   0
+
+                Assert.HasCount(1, Array.Empty<int>())
+                """);
         o.WasToStringCalled.Should().BeTrue();
     }
 
@@ -53,7 +70,15 @@ public void NotAny_WhenNotEmpty_ShouldFail()
         var collection = new List<int> { 1 };
         Action action = () => Assert.IsEmpty(collection);
         action.Should().Throw<Exception>()
-            .WithMessage("Assert.IsEmpty failed. Expected collection of size 0. Actual: 1. 'collection' expression: 'collection'.");
+            .WithMessage(
+                """
+                Assertion failed. Expected collection to be empty.
+
+                expected count: 0
+                actual count:   1
+
+                Assert.IsEmpty(collection)
+                """);
     }
 
     public async Task NotAny_InterpolatedString_WhenNotEmpty_ShouldFail()
@@ -63,7 +88,16 @@ public async Task NotAny_InterpolatedString_WhenNotEmpty_ShouldFail()
         DateTime dateTime = DateTime.Now;
         Func<Task> action = async () => Assert.IsEmpty(collection, $"User-provided message. {o}, {o,35}, {await GetHelloStringAsync()}, {new DummyIFormattable()}, {dateTime:tt}, {dateTime,5:tt}");
         (await action.Should().ThrowAsync<Exception>())
-            .WithMessage($"Assert.IsEmpty failed. Expected collection of size 0. Actual: 1. 'collection' expression: 'collection'. User-provided message. DummyClassTrackingToStringCalls,     DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {string.Format(null, "{0:tt}", dateTime)}, {string.Format(null, "{0,5:tt}", dateTime)}");
+            .WithMessage(
+                $$"""
+                Assertion failed. Expected collection to be empty.
+                User-provided message. DummyClassTrackingToStringCalls,     DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {{string.Format(null, "{0:tt}", dateTime)}}, {{string.Format(null, "{0,5:tt}", dateTime)}}
+
+                expected count: 0
+                actual count:   1
+
+                Assert.IsEmpty(collection)
+                """);
         o.WasToStringCalled.Should().BeTrue();
     }
 
@@ -194,7 +228,14 @@ public void Any_WhenNoItem_ShouldFail()
     {
         Action action = () => Assert.IsNotEmpty(Array.Empty<int>());
         action.Should().Throw<Exception>()
-            .WithMessage("Assert.IsNotEmpty failed. Expected collection to contain any item but it is empty. 'collection' expression: 'Array.Empty<int>()'.");
+            .WithMessage(
+                """
+                Assertion failed. Expected collection to not be empty.
+
+                actual count: 0
+
+                Assert.IsNotEmpty(Array.Empty<int>())
+                """);
     }
 
     public async Task Any_InterpolatedString_WhenNoItem_ShouldFail()
@@ -203,7 +244,15 @@ public async Task Any_InterpolatedString_WhenNoItem_ShouldFail()
         DateTime dateTime = DateTime.Now;
         Func<Task> action = async () => Assert.IsNotEmpty(Array.Empty<string>(), $"User-provided message. {o}, {o,35}, {await GetHelloStringAsync()}, {new DummyIFormattable()}, {dateTime:tt}, {dateTime,5:tt}");
         (await action.Should().ThrowAsync<Exception>())
-            .WithMessage($"Assert.IsNotEmpty failed. Expected collection to contain any item but it is empty. 'collection' expression: 'Array.Empty<string>()'. User-provided message. DummyClassTrackingToStringCalls,     DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {string.Format(null, "{0:tt}", dateTime)}, {string.Format(null, "{0,5:tt}", dateTime)}");
+            .WithMessage(
+                $$"""
+                Assertion failed. Expected collection to not be empty.
+                User-provided message. DummyClassTrackingToStringCalls,     DummyClassTrackingToStringCalls, Hello, DummyIFormattable.ToString(), {{string.Format(null, "{0:tt}", dateTime)}}, {{string.Format(null, "{0,5:tt}", dateTime)}}
+
+                actual count: 0
+
+                Assert.IsNotEmpty(Array.Empty<string>())
+                """);
         o.WasToStringCalled.Should().BeTrue();
     }
 }

From 843346d7c6329f015fd645b774be418bd9f8082b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Amaury=20Lev=C3=A9?= <amaury@nerdyduck.dev>
Date: Fri, 15 May 2026 18:24:03 +0200
Subject: [PATCH 2/4] Fix Assert.Count call-site formatting

Use invariant formatting for HasCount call-site arguments while keeping evidence culture-aware, and replace magic assertion-name strings with nameof usage. Add a regression test covering culture-specific negative-sign formatting for the displayed call site.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../TestFramework/Assertions/Assert.Count.cs  | 26 +++++++++-------
 .../Assertions/AssertTests.Items.cs           | 31 +++++++++++++++++++
 2 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/src/TestFramework/TestFramework/Assertions/Assert.Count.cs b/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
index 038dfc3da0..e92a6daf1c 100644
--- a/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
+++ b/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
@@ -239,7 +239,7 @@ public static void IsNotEmpty(IEnumerable collection, string? message = "", [Cal
 #pragma warning disable IDE0060 // Remove unused parameter
     public static void HasCount<T>(int expected, IEnumerable<T> collection, [InterpolatedStringHandlerArgument(nameof(expected), nameof(collection))] ref AssertCountInterpolatedStringHandler<T> message, [CallerArgumentExpression(nameof(collection))] string collectionExpression = "")
 #pragma warning restore IDE0060 // Remove unused parameter
-        => message.ComputeAssertion("HasCount", collectionExpression);
+        => message.ComputeAssertion(nameof(HasCount), collectionExpression);
 
     /// <summary>
     /// Tests whether the collection has the expected count/length.
@@ -253,7 +253,7 @@ public static void HasCount<T>(int expected, IEnumerable<T> collection, [Interpo
     /// Users shouldn't pass a value for this parameter.
     /// </param>
     public static void HasCount<T>(int expected, IEnumerable<T> collection, string? message = "", [CallerArgumentExpression(nameof(collection))] string collectionExpression = "")
-        => HasCount("HasCount", expected, collection, message, collectionExpression);
+        => HasCount(nameof(HasCount), expected, collection, message, collectionExpression);
 
     /// <summary>
     /// Tests whether the collection has the expected count/length.
@@ -266,7 +266,7 @@ public static void HasCount<T>(int expected, IEnumerable<T> collection, string?
     /// Users shouldn't pass a value for this parameter.
     /// </param>
     public static void HasCount(int expected, IEnumerable collection, string? message = "", [CallerArgumentExpression(nameof(collection))] string collectionExpression = "")
-        => HasCount("HasCount", expected, collection, message, collectionExpression);
+        => HasCount(nameof(HasCount), expected, collection, message, collectionExpression);
 
     #endregion // HasCount
 
@@ -285,7 +285,7 @@ public static void HasCount(int expected, IEnumerable collection, string? messag
 #pragma warning disable IDE0060 // Remove unused parameter
     public static void IsEmpty<T>(IEnumerable<T> collection, [InterpolatedStringHandlerArgument(nameof(collection))] ref AssertCountInterpolatedStringHandler<T> message, [CallerArgumentExpression(nameof(collection))] string collectionExpression = "")
 #pragma warning restore IDE0060 // Remove unused parameter
-        => message.ComputeAssertion("IsEmpty", collectionExpression);
+        => message.ComputeAssertion(nameof(IsEmpty), collectionExpression);
 
     /// <summary>
     /// Tests that the collection is empty.
@@ -298,7 +298,7 @@ public static void IsEmpty<T>(IEnumerable<T> collection, [InterpolatedStringHand
     /// Users shouldn't pass a value for this parameter.
     /// </param>
     public static void IsEmpty<T>(IEnumerable<T> collection, string? message = "", [CallerArgumentExpression(nameof(collection))] string collectionExpression = "")
-        => HasCount("IsEmpty", 0, collection, message, collectionExpression);
+        => HasCount(nameof(IsEmpty), 0, collection, message, collectionExpression);
 
     /// <summary>
     /// Tests that the collection is empty.
@@ -310,7 +310,7 @@ public static void IsEmpty<T>(IEnumerable<T> collection, string? message = "", [
     /// Users shouldn't pass a value for this parameter.
     /// </param>
     public static void IsEmpty(IEnumerable collection, string? message = "", [CallerArgumentExpression(nameof(collection))] string collectionExpression = "")
-        => HasCount("IsEmpty", 0, collection, message, collectionExpression);
+        => HasCount(nameof(IsEmpty), 0, collection, message, collectionExpression);
 
     #endregion // IsEmpty
 
@@ -331,23 +331,25 @@ private static void HasCount(string assertionName, int expected, IEnumerable col
     [DoesNotReturn]
     private static void ReportAssertCountFailed(string assertionName, int expectedCount, int actualCount, string? userMessage, string collectionExpression)
     {
-        string summary = assertionName == "IsEmpty"
+        bool isEmptyAssertion = string.Equals(assertionName, nameof(IsEmpty), StringComparison.Ordinal);
+        string summary = isEmptyAssertion
             ? FrameworkMessages.IsEmptyFailedSummary
             : FrameworkMessages.HasCountFailedSummary;
 
-        string expectedText = expectedCount.ToString(CultureInfo.CurrentCulture);
+        string expectedEvidenceText = expectedCount.ToString(CultureInfo.CurrentCulture);
+        string expectedCallSiteText = expectedCount.ToString(CultureInfo.InvariantCulture);
         string actualText = actualCount.ToString(CultureInfo.CurrentCulture);
         EvidenceBlock evidence = EvidenceBlock.Create()
-            .AddLine("expected count:", expectedText)
+            .AddLine("expected count:", expectedEvidenceText)
             .AddLine("actual count:", actualText);
 
         StructuredAssertionMessage structured = new(summary);
         structured.WithUserMessage(userMessage);
         structured.WithEvidence(evidence);
-        structured.WithExpectedAndActual(expectedText, actualText);
-        structured.WithCallSiteExpression(assertionName == "IsEmpty"
+        structured.WithExpectedAndActual(expectedEvidenceText, actualText);
+        structured.WithCallSiteExpression(isEmptyAssertion
             ? FormatCallSiteExpression($"Assert.{assertionName}", collectionExpression, "<collection>")
-            : FormatCallSiteExpression($"Assert.{assertionName}", expectedText, collectionExpression, "<expected>", "<collection>"));
+            : FormatCallSiteExpression($"Assert.{assertionName}", expectedCallSiteText, collectionExpression, "<expected>", "<collection>"));
 
         ReportAssertFailed(structured);
     }
diff --git a/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs b/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
index a20a0d5be9..4dd180314a 100644
--- a/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
+++ b/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.Globalization;
+
 using AwesomeAssertions;
 
 namespace Microsoft.VisualStudio.TestPlatform.TestFramework.UnitTests;
@@ -55,6 +57,35 @@ Assertion failed. Expected collection to contain a specific number of elements.
         o.WasToStringCalled.Should().BeTrue();
     }
 
+    public void Count_WhenCurrentCultureUsesCustomNegativeSign_ShouldUseInvariantCallSiteValue()
+    {
+        CultureInfo originalCulture = CultureInfo.CurrentCulture;
+        CultureInfo customCulture = (CultureInfo)CultureInfo.InvariantCulture.Clone();
+        customCulture.NumberFormat.NegativeSign = "−";
+
+        try
+        {
+            CultureInfo.CurrentCulture = customCulture;
+            var collection = new List<int>();
+
+            Action action = () => Assert.HasCount(-1, collection);
+            action.Should().Throw<Exception>()
+                .WithMessage(
+                    """
+                    Assertion failed. Expected collection to contain a specific number of elements.
+
+                    expected count: −1
+                    actual count:   0
+
+                    Assert.HasCount(-1, collection)
+                    """);
+        }
+        finally
+        {
+            CultureInfo.CurrentCulture = originalCulture;
+        }
+    }
+
     public void NotAny_WhenEmpty_ShouldPass()
         => Assert.IsEmpty(Array.Empty<int>());
 

From 201784a7895c9619f35a3b02929ca31978534483 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Amaury=20Lev=C3=A9?= <amauryleve@microsoft.com>
Date: Sat, 16 May 2026 13:48:17 +0200
Subject: [PATCH 3/4] Apply suggestion from @Evangelink

---
 .../TestFramework.UnitTests/Assertions/AssertTests.Items.cs     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs b/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
index 1a1f846433..d3b717e3b7 100644
--- a/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
+++ b/test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.Items.cs
@@ -60,7 +60,7 @@ Assertion failed. Expected collection to contain a specific number of elements.
     public void Count_WhenCurrentCultureUsesCustomNegativeSign_ShouldUseInvariantCallSiteValue()
     {
         CultureInfo originalCulture = CultureInfo.CurrentCulture;
-        CultureInfo customCulture = (CultureInfo)CultureInfo.InvariantCulture.Clone();
+        var customCulture = (CultureInfo)CultureInfo.InvariantCulture.Clone();
         customCulture.NumberFormat.NegativeSign = "−";
 
         try

From ef50f919047245e05514b7722a54723c79ae66d3 Mon Sep 17 00:00:00 2001
From: Copilot <223556219+Copilot@users.noreply.github.com>
Date: Sat, 16 May 2026 16:31:23 +0200
Subject: [PATCH 4/4] Address review: culture-aware actual count and
 WithExpectedAndActual for IsNotEmpty

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 src/TestFramework/TestFramework/Assertions/Assert.Count.cs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/TestFramework/TestFramework/Assertions/Assert.Count.cs b/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
index 2d0120c4e4..470f8d6383 100644
--- a/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
+++ b/src/TestFramework/TestFramework/Assertions/Assert.Count.cs
@@ -382,12 +382,14 @@ private static void ReportAssertCountFailed(string assertionName, int expectedCo
     [DoesNotReturn]
     private static void ReportAssertIsNotEmptyFailed(string? userMessage, string collectionExpression)
     {
+        string actualText = 0.ToString(CultureInfo.CurrentCulture);
         EvidenceBlock evidence = EvidenceBlock.Create()
-            .AddLine("actual count:", "0");
+            .AddLine("actual count:", actualText);
 
         StructuredAssertionMessage structured = new(FrameworkMessages.IsNotEmptyFailedSummary);
         structured.WithUserMessage(userMessage);
         structured.WithEvidence(evidence);
+        structured.WithExpectedAndActual("> 0", actualText);
         structured.WithCallSiteExpression(FormatCallSiteExpression("Assert.IsNotEmpty", collectionExpression, "<collection>"));
 
         ReportAssertFailed(structured);