Let tools take a list of strings as an argument

app/Tests/Tools/ToolCalling/ToolParameterSchemaBuilderTests.cs

@@ -0,0 +1,52 @@
+using System.Text.Json.Nodes;
+
+using AIStudio.Tools.ToolCallingSystem;
+
+namespace AIStudio.Tests.Tools.ToolCalling;
+
+/// <summary>
+/// Checks the plain JSON Schema a tool describes its arguments with.
+/// </summary>
+/// <remarks>
+/// This is the form Anthropic and every host without strict mode receive as written, so it has to
+/// mean exactly what the tool expects. The translation for strict mode is checked on its own, see
+/// OpenAIStrictToolSchemaTests.
+/// </remarks>
+[TestFixture]
+public sealed class ToolParameterSchemaBuilderTests
+{
+    [Test]
+    public void AListOfChoicesRestrictsEveryEntry()
+    {
+        var schema = Built(ToolParameterSchemaBuilder.Create().OptionalStringArray("data_source_ids", "The data sources.", "first", "second"));
+        var property = schema["properties"]!["data_source_ids"]!;
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(property["type"]!.GetValue<string>(), Is.EqualTo("array"));
+            Assert.That(property["description"]!.GetValue<string>(), Is.EqualTo("The data sources."));
+            Assert.That(property["items"]!["type"]!.GetValue<string>(), Is.EqualTo("string"));
+            Assert.That(property["items"]!["enum"]!.AsArray().Select(value => value!.GetValue<string>()), Is.EqualTo(new[] { "first", "second" }));
+        });
+    }
+
+    [Test]
+    public void AListWithoutChoicesTakesAnyString()
+    {
+        var items = Built(ToolParameterSchemaBuilder.Create().OptionalStringArray("tags", "Some tags."))["properties"]!["tags"]!["items"]!;
+
+        Assert.That(items["enum"], Is.Null, "An empty enum would allow no entry at all rather than any.");
+    }
+
+    [Test]
+    public void AnOptionalListIsNotRequired()
+    {
+        var schema = Built(ToolParameterSchemaBuilder.Create()
+            .RequiredString("query", "The search query.")
+            .OptionalStringArray("data_source_ids", "The data sources.", "first"));
+
+        Assert.That(schema["required"]!.AsArray().Select(name => name!.GetValue<string>()), Is.EqualTo(new[] { "query" }));
+    }
+
+    private static JsonNode Built(ToolParameterSchemaBuilder builder) => JsonNode.Parse(builder.Build().GetRawText())!;
+}