Sent strict tool schemas only to providers that enforce them

app/Tests/Provider/ToolCalling/OpenAIStrictToolSchemaTests.cs

@@ -0,0 +1,107 @@
+using System.Text.Json.Nodes;
+
+using AIStudio.Provider.OpenAI;
+using AIStudio.Tools.ToolCallingSystem;
+
+namespace AIStudio.Tests.Provider.ToolCalling;
+
+/// <summary>
+/// Checks how a tool's parameter schema is translated into the form OpenAI's strict mode requires.
+/// </summary>
+/// <remarks>
+/// Strict mode wants every argument required and says "may be left out" by allowing null instead.
+/// The translation has to keep what the schema means: an argument the tool can do without stays
+/// one the model can leave empty, and an argument the tool needs stays exactly as it was.
+/// </remarks>
+[TestFixture]
+public sealed class OpenAIStrictToolSchemaTests
+{
+    [Test]
+    public void AnOptionalArgumentMayBeNullInstead()
+    {
+        var properties = Converted(ToolParameterSchemaBuilder.Create()
+            .RequiredString("query", "The search query.")
+            .OptionalString("language", "The language.")
+            .OptionalInteger("page", "The page."))["properties"]!;
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(Types(properties["language"]!), Is.EqualTo(new[] { "string", "null" }));
+            Assert.That(Types(properties["page"]!), Is.EqualTo(new[] { "integer", "null" }));
+        });
+    }
+
+    [Test]
+    public void AnOptionalChoiceOffersNullAmongItsValues()
+    {
+        var timeRange = Converted(ToolParameterSchemaBuilder.Create()
+            .RequiredString("query", "The search query.")
+            .OptionalEnum("time_range", "The time range.", "day", "month", "year"))["properties"]!["time_range"]!;
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(Types(timeRange), Is.EqualTo(new[] { "string", "null" }));
+            Assert.That(timeRange["enum"]!.AsArray().Select(value => value?.GetValue<string>()), Is.EqualTo(new[] { null, "day", "month", "year" }));
+        });
+    }
+
+    [Test]
+    public void ARequiredArgumentStaysAsItIs()
+    {
+        var query = Converted(ToolParameterSchemaBuilder.Create()
+            .RequiredString("query", "The search query.")
+            .OptionalString("language", "The language."))["properties"]!["query"]!;
+
+        Assert.That(query["type"]!.GetValue<string>(), Is.EqualTo("string"));
+    }
+
+    [Test]
+    public void EveryArgumentIsRequiredInTheOrderOfTheProperties()
+    {
+        //
+        // The order has to be stable across requests, because prompt caching depends on it. The
+        // optional argument comes first here, so an order taken from the old required list would
+        // show.
+        //
+        var schema = Converted(ToolParameterSchemaBuilder.Create()
+            .OptionalString("language", "The language.")
+            .RequiredString("query", "The search query."));
+
+        Assert.That(schema["required"]!.AsArray().Select(name => name!.GetValue<string>()), Is.EqualTo(new[] { "language", "query" }));
+    }
+
+    [Test]
+    public void ExtraArgumentsStayRefused()
+    {
+        var schema = Converted(ToolParameterSchemaBuilder.Create()
+            .RequiredString("query", "The search query.")
+            .OptionalString("language", "The language."));
+
+        Assert.That(schema["additionalProperties"]!.GetValue<bool>(), Is.False);
+    }
+
+    [Test]
+    public void ASchemaWithoutOptionalArgumentsIsLeftUntouched()
+    {
+        var parameters = ToolParameterSchemaBuilder.Create()
+            .RequiredString("url", "The address of the page.")
+            .Build();
+
+        var converted = OpenAIStrictToolSchema.FromToolParameters(parameters);
+        Assert.That(JsonNode.DeepEquals(JsonNode.Parse(converted.GetRawText()), JsonNode.Parse(parameters.GetRawText())), Is.True);
+    }
+
+    /// <summary>
+    /// Builds the schema and returns it the way strict mode receives it.
+    /// </summary>
+    private static JsonNode Converted(ToolParameterSchemaBuilder builder) => JsonNode.Parse(OpenAIStrictToolSchema.FromToolParameters(builder.Build()).GetRawText())!;
+
+    /// <summary>
+    /// Reads the types a property allows, whether it names one or several.
+    /// </summary>
+    private static string[] Types(JsonNode property) => property["type"] switch
+    {
+        JsonArray types => types.Select(type => type!.GetValue<string>()).ToArray(),
+        var type => [type!.GetValue<string>()],
+    };
+}