Table of Contents

Text and JSON

Snapshot.VerifyTextAsync and Snapshot.VerifyJsonAsync check other output the same way as PDFs, with the same received and verified files, accept mode and report. A test project can keep every kind of snapshot in one place. Snapshot.VerifyText and Snapshot.VerifyJson are the synchronous versions, for a test that isn't async. Snapshot.VerifyFileAsync(path) checks a file already on disk, picking a PDF, Word, JSON or text snapshot from its extension, with the suite's default options.

Text

[Fact]
public async Task Export_ShouldMatchApprovedSnapshot_WhenGenerated()
{
    string csv = await TrailExporter.CreateCsvAsync();

    await Snapshot.VerifyTextAsync(csv);
}
  • Compared exactly, spaces included. The one exception: CRLF line endings are read as LF.
  • Saved as {name}.verified.txt. Use o => o.Extension("csv") to save as {name}.verified.csv instead.
  • A verified file that starts with a UTF-8 byte-order mark matches as if it didn't, so files approved by other tools carry over.

JSON

[Fact]
public async Task Job_ShouldMatchApprovedSnapshot_WhenSubmitted()
{
    string json = await client.GetStringAsync("/jobs/latest");

    await Snapshot.VerifyJsonAsync(json);
}

The JSON is written the same way every time before it's compared:

  • Indented with two spaces, keys in the order written, numbers exactly as written.
  • Strings (values or keys) that are a GUID or an ISO 8601 timestamp, such as "2026-10-28T09:15:00Z", become Guid_1 and Date_1. The same value always gets the same token, so the snapshot still shows that two IDs match.
  • Dates written for people, such as a guide's "November 14, 2020", and anything inside longer text are kept, because that is content.
  • Invalid JSON fails the test with the parser's message.

Saved as {name}.verified.json.

Options

Option Text JSON
ScrubText(regex, replacement) Replaces your pattern anywhere Replaces your pattern anywhere
ScrubDates() Replaces dates anywhere with Date_1, Date_2, ... Also scrubs dates inside longer text
ScrubGuids() Replaces GUIDs anywhere with Guid_1, Guid_2, ... Also scrubs GUIDs inside longer text
KeepDates() Undoes an earlier ScrubDates() Keeps timestamp strings as they are
KeepGuids() Undoes an earlier ScrubGuids() Keeps GUID strings as they are 
await Snapshot.VerifyTextAsync(csv, configure: options => options
    .ScrubText(new Regex(@"Permit \d+"), "Permit N")
    .ScrubDates());

await Snapshot.VerifyJsonAsync(json, configure: options => options.KeepGuids());

Reading a failure

Text and JSON are compared line by line. A failure lists each changed line by number, with the changed words marked:

2 change(s): 1 removed, 1 text
~ text line 3
    [-"b": 2,-] {+"c": 4+}
- removed line 4
      "c": 3

See also