YAML

using Nullean.Snapshots.Yaml;

config.Should().MatchYamlSnapshot();
config.Should().BeYaml("items: [{id: 1}]");

YAML snapshots are stored as written: comments and layout survive, nothing is re-emitted. They are compared as trees, the same way as JSON, with differences pointing at line and column in the verified file:

YAML did not match snapshot: tests/App.Tests/.snapshots/ConfigTests/Renders.verified.yml
3 difference(s):
$.items[0].name   expected "kibana"   actual "Kibana"   (verified.yml:3:11)
$.items[1]        missing in actual   (verified.yml:5:5)
$.meta.extra      unexpected in actual

Typing

Plain scalars are typed with the YAML 1.2 core schema, not 1.1:

Written	Is
`true`, `True`, `TRUE`, `false`, …	a boolean
`yes`, `no`, `on`, `off`	a string
`null`, `Null`, `NULL`, `~`, nothing	null
`42`, `+1`, `017`	a decimal integer
`0o17`, `0x1F`	an integer, equal to its decimal value
`1_000`, `0b101`	a string
`1.5`, `1e3`, `.inf`, `-.Inf`, `.nan`	a float
`"true"`, `'1'`, block scalars	a string

!!str, !!int, !!float, !!bool and !!null tags apply; local tags such as !ref are typed as if they were not there.

Anchors and merge keys

Aliases are the anchored value, and << merge keys are resolved: explicit keys win over merged ones, and of several merged mappings the first wins. A YAML snapshot with anchors compares equal to the same data written out in full.

A stream of several documents compares document by document, with paths such as $doc[1].name.

For a short value there is MatchInlineYamlSnapshot, which keeps the expected value in the test as a literal: see inline snapshots.