Adopted further C# 14 and .NET 10 features (#1158)

app/Tests/Assistants/VisualBriefing/VisualBriefingDuplicateFieldTests.cs

@@ -0,0 +1,44 @@
+using AIStudio.Assistants.VisualBriefing;
+
+namespace AIStudio.Tests.Assistants.VisualBriefing;
+
+/// <summary>
+/// Checks that the Visual Briefing assistant refuses a model answer which names a field twice.
+/// </summary>
+/// <remarks>
+/// The checks of the assistant would see one of the two values, while the browser which runs the
+/// finished briefing may see the other. The repair turn names the field, so that the model can fix it.
+/// </remarks>
+[TestFixture]
+public sealed class VisualBriefingDuplicateFieldTests
+{
+    [TestCase("""{"contractVersion":1,"contractVersion":2}""", "contractVersion", "$.contractVersion", TestName = "A field of the answer")]
+    [TestCase("""{"contractVersion":1,"facts":[{"id":"fact-1","id":"fact-2"}]}""", "id", "$.facts[0].id", TestName = "A field of an object in a list")]
+    [TestCase("""{"facts":[{"value":{"unit":"EUR","unit":"USD"}}]}""", "unit", "$.facts[0].value.unit", TestName = "A field deep inside a value")]
+    [TestCase("```json\n{\"contractVersion\":1,\"contractVersion\":2}\n```", "contractVersion", "$.contractVersion", TestName = "A field of an answer in a code block")]
+    public void AnAnswerWhichNamesAFieldTwiceIsRefused(string answer, string repeatedField, string path)
+    {
+        var result = VisualBriefingStructuredResponseProcessor.Process<VisualBriefingEvidenceResponse>(answer, _ => null);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(result.Response, Is.Null);
+            Assert.That(result.Issue?.Code, Is.EqualTo(VisualBriefingFailureCode.RESPONSE_JSON_INVALID));
+            Assert.That(result.Issue?.Rule, Is.EqualTo(VisualBriefingValidationRule.JSON_INVALID));
+            Assert.That(result.Issue?.Diagnostic?.IssueKind, Is.EqualTo(VisualBriefingStructuredResponseIssueKind.DUPLICATE_FIELD));
+            Assert.That(result.Issue?.Diagnostic?.FieldName, Is.EqualTo(repeatedField));
+            Assert.That(result.Issue?.Diagnostic?.JsonPath, Is.EqualTo(path));
+            Assert.That(result.Issue?.Issue, Does.Contain($"'{repeatedField}'"), "The repair turn names the field.");
+        }
+    }
+
+    [Test]
+    public void TheSameFieldInTwoObjectsIsNoDuplicate()
+    {
+        var result = VisualBriefingStructuredResponseProcessor.Process<VisualBriefingEvidenceResponse>(
+            """{"contractVersion":1,"facts":[{"id":"fact-1"},{"id":"fact-2"}]}""",
+            _ => null);
+
+        Assert.That(result.Issue?.Diagnostic?.IssueKind, Is.Not.EqualTo(VisualBriefingStructuredResponseIssueKind.DUPLICATE_FIELD));
+    }
+}