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MfileSnapshot
Bun

method

test.default.TestContextAssert.fileSnapshot

value: any,
path: string,
options?: AssertSnapshotOptions
): void;

This function serializes value and writes it to the file specified by path.

test('snapshot test with default serialization', (t) => {
  t.assert.fileSnapshot({ value1: 1, value2: 2 }, './snapshots/snapshot.json');
});

This function differs from context.assert.snapshot() in the following ways:

  • The snapshot file path is explicitly provided by the user.
  • Each snapshot file is limited to a single snapshot value.
  • No additional escaping is performed by the test runner.

These differences allow snapshot files to better support features such as syntax highlighting.

@param value

A value to serialize to a string. If Node.js was started with the --test-update-snapshots flag, the serialized value is written to path. Otherwise, the serialized value is compared to the contents of the existing snapshot file.

@param path

The file where the serialized value is written.

@param options

Optional configuration options.