Generated the JSON contracts of the stored data at compile time (#1148)

app/Tests/Serialization/JsonContractTests.cs

@@ -0,0 +1,23 @@
+namespace AIStudio.Tests.Serialization;
+
+/// <summary>
+/// Checks that the contracts AI Studio uses for its JSON match those reflection builds.
+/// </summary>
+/// <remarks>
+/// AI Studio wrote all its files with contracts which reflection built. Any other contract, e.g., one which
+/// source generation builds, has to match them in every detail, or AI Studio no longer reads what it wrote
+/// before: a property with another name, without a setter, or without its converter silently loses its value.
+/// </remarks>
+[TestFixture]
+public sealed class JsonContractTests
+{
+    [TestCaseSource(typeof(JsonTestRoots), nameof(JsonTestRoots.Stored))]
+    public void TheContractsMatchThoseOfReflection(JsonTestRoot root)
+    {
+        var baseline = JsonReflectionBaseline.Of(root.Options);
+        var expected = JsonTypeGraph.Collect(root.Type, baseline).Select(type => JsonContractDescription.Describe(baseline.GetTypeInfo(type)));
+        var actual = JsonTypeGraph.Collect(root.Type, root.Options).Select(type => JsonContractDescription.Describe(root.Options.GetTypeInfo(type)));
+
+        Assert.That(actual, Is.EqualTo(expected));
+    }
+}