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

app/Tests/Provider/AdditionalApiParametersParserTests.cs

@@ -0,0 +1,46 @@
+using AIStudio.Provider;
+
+namespace AIStudio.Tests.Provider;
+
+/// <summary>
+/// Checks how the additional API parameters of a provider are read.
+/// </summary>
+/// <remarks>
+/// The dialog for providers refuses a parameter named twice, but a configuration plugin brings its
+/// providers past the dialog. Read anyway, such parameters would leave it open which of the values
+/// reaches the provider, and they used to break every request with an exception nobody caught.
+/// </remarks>
+[TestFixture]
+public sealed class AdditionalApiParametersParserTests
+{
+    [Test]
+    public void TheParametersAreRead()
+    {
+        var isRead = AdditionalApiParametersParser.TryParse("""
+            "temperature": 0.5,
+            "reasoning": { "effort": "low" }
+            """, out var parameters, out var errorMessage);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(isRead, Is.True);
+            Assert.That(errorMessage, Is.Null);
+            Assert.That(parameters["temperature"], Is.EqualTo(0.5));
+            Assert.That(parameters["reasoning"], Is.EqualTo(new Dictionary<string, object> { ["effort"] = "low" }));
+        }
+    }
+
+    [TestCase("\"temperature\": 0.5, \"temperature\": 0.7", "temperature", TestName = "A parameter named twice")]
+    [TestCase("\"reasoning\": { \"effort\": \"low\", \"effort\": \"high\" }", "effort", TestName = "A field named twice inside a parameter")]
+    public void AParameterNamedTwiceIsRefused(string additionalParameters, string repeatedName)
+    {
+        var isRead = AdditionalApiParametersParser.TryParse(additionalParameters, out var parameters, out var errorMessage);
+
+        using (Assert.EnterMultipleScope())
+        {
+            Assert.That(isRead, Is.False);
+            Assert.That(parameters, Is.Empty);
+            Assert.That(errorMessage, Does.Contain($"'{repeatedName}'"), "The log names the parameter to correct.");
+        }
+    }
+}