Matcher hasHeaders(Map<String, dynamic> matchers, { bool failIfContainsUnmatchedHeader: false })

Validates that a TestResponse has the specified HTTP headers.

This matcher only validates the HTTP headers. See hasResponse for more details. Usage:

  var response = await client.request("/foo").get();
  expect(response, hasHeaders(partial({"x-request-id": 4})));

Source 

Matcher hasHeaders(Map<String, dynamic> matchers,
        {bool failIfContainsUnmatchedHeader: false}) =>
    new HTTPResponseMatcher(
        null,
        new HTTPHeaderMatcher(matchers, failIfContainsUnmatchedHeader),
        null);