v0.6.0

[0.6.0] - 2026-07-11: JSON subset matching and typed extraction

Minor release. Adds subset (contains) assertions and typed value extraction. Purely additive.

Added

• Assert.That(actual).ContainsJson(expectedSubset) asserts that a JSON document contains an expected subset: every property in the expected document must be present in the actual document with an equivalent value (recursively), while the actual document may carry additional properties. This is the subset counterpart of IsEquivalentJsonTo (full equality), for the common case where a response carries fields a test does not want to pin. A JSON string, a JsonElement, and an HttpResponseMessage (body read with a flowed CancellationToken) are accepted as the actual value; the expected subset is a JSON string. Matching is independent of object-property order and number form. An expected array asserts a positional prefix (the actual array may be longer); IgnoreArrayOrder() matches expected elements against the actual array as a multiset subset, and IgnorePath(...) excludes a path, both through the configure overload. On failure the message lists every missing or mismatched path in one report, each with its category and a rendered view of both sides, so a single run enumerates every field that is wrong.
• JsonEquivalence.ContainsAll(expected, actual, options) (framework-agnostic core) exposes the subset comparison directly over JSON strings or JsonElements, returning every JsonDifference found (empty when the actual document contains the subset). JsonFailureMessage.ContainsMismatch(differences) renders the multi-difference failure text.
• GetJsonValue<T>(path), GetJsonString(path), and GetJsonElement(path) read a typed value out of a JSON document at a path and return it, for a test that needs the value (pulling an id to drive the next request, reading a count to cross-check an array length) rather than an assertion. GetJsonValue<T> parses the value as any IParsable<T> (int / long / bool / Guid / DateTimeOffset, ...) from a JSON string or a JSON number literal, using CultureInfo.InvariantCulture; GetJsonElement returns a detached copy that stays valid after the source document is disposed. Each is available over a JSON string, a JsonElement, and (as GetJsonValueAsync / GetJsonStringAsync / GetJsonElementAsync) an HttpResponseMessage. A failure to resolve the path, convert the value, or parse the source throws JsonExtractionException with the same path-context message the assertions render, replacing a hand-rolled JsonDocument.Parse(...).GetProperty(...).GetInt32() chain and its bare BCL exceptions.