Class JsonRoundtripAssertions

Namespace

JsonAssertions.TUnit

Assembly

JsonAssertions.TUnit.dll

Fluent assertion that a typed value round-trips cleanly through STJ source-gen via the consumer's JsonTypeInfo<T>. Catches the common "we added a property and forgot to update the JsonSerializerContext" regression class: a missing [JsonSerializable(typeof(T))] entry or a property the context doesn't know about causes the round-trip to produce a different JSON string than the original.

[SuppressMessage("Usage", "VSTHRD200:Use \"Async\" suffix for async methods", Justification = "This is a [GenerateAssertion] source method: the method name becomes the fluent chain entry point (Assert.That(value).RoundtripsCleanlyVia(...)), so an Async suffix would corrupt the assertion surface. The method is synchronous anyway (no IO, no await).")]
public static class JsonRoundtripAssertions

Inheritance

object

JsonRoundtripAssertions

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

Mechanism: Serialize(value, jsonTypeInfo) -> Deserialize(json1, jsonTypeInfo) -> Serialize(roundtripped, jsonTypeInfo). The two serialized strings are compared ordinally; if they differ, the round-trip is lossy and the assertion fails with both JSON strings rendered for diagnosis.

AOT-clean: the supplied JsonTypeInfo<T> is the source-generated entry for T in the consumer's JsonSerializerContext; the assertion uses no runtime reflection.

Use case: consumers shipping AOT-compatible web APIs typically have a JsonSerializerContext but rarely write regression tests verifying that EVERY type in the context round-trips correctly. A RoundtripsCleanlyVia regression test for each type in each context is a 1-2 hour sweep that catches future "added a property, forgot the context" bugs at CI time.

Methods

RoundtripsCleanlyVia<T>(T, JsonTypeInfo<T>)

Asserts the value round-trips cleanly through the supplied JsonTypeInfo<T>: serializing it produces a JSON string that, when deserialized and re-serialized via the same context, yields a byte-identical JSON string. Catches missing [JsonSerializable] entries, property orderings that drift on round-trip, and serializer-options-vs-context inconsistencies.

[GenerateAssertion]
public static AssertionResult RoundtripsCleanlyVia<T>(this T value, JsonTypeInfo<T> jsonTypeInfo)

Parameters

value T

The value to round-trip.

jsonTypeInfo JsonTypeInfo<T>

The JsonTypeInfo<T> from the consumer's JsonSerializerContext; AOT-clean.

Returns

AssertionResult

Type Parameters

T

The value type whose round-trip is asserted.