Skip to main content

matcher

Criteria for deciding which requests to mock.

Note that if you use matchers that target anything other than the url string, you may also need to add a name to your matcher object so that a) you can add multiple mocks on the same url that differ only in other properties (e.g. query strings or headers) b) if you inspect the result of the fetch calls, retrieving the correct results will be easier.

Argument values​

Note that if using end: or an exact url matcher, fetch-mock (for good reason) is unable to distinguish whether URLs without a path end in a trailing slash or not i.e. http://thing is treated the same as http://thing/

*

{String}

Matches any url

url​

{String|URL} Match an exact url. Can be defined using a string or a URL instance, e.g. "http://www.site.com/page.html"

begin:...​

{String} Match a url beginning with a string, e.g. "begin:http://www.site.com"

end:...​

{String} Match a url ending with a string, e.g. "end:.jpg"

path:...​

{String} Match a url which has a given path, e.g. "path:/posts/2018/7/3"

glob:...​

{String} Match a url using a glob pattern, e.g. "glob:http://*.*"

express:...​

{String} Match a url that satisfies an express style path, e.g. "express:/user/:user"

See also the params option before for matching on the values of express parameters.

RegExp​

{RegExp} Match a url that satisfies a regular expression, e.g. /(article|post)\/\d+/

Function​

{Function} Match if a function returns something truthy. The function will be passed the url and options fetch was called with. If fetch was called with a Request instance, it will be passed url and options inferred from the Request instance, with the original Request will be passed as a third argument.

This can also be set as a functionMatcher in the options parameter, and in this way powerful arbitrary matching criteria can be combined with the ease of the declarative matching rules above.

Examples​

  • (url, {headers}) => !!headers.Authorization
  • (_, _, request) => !!request.headers.get('Authorization')

Options Object​

{Object}

The url and function matchers described above can be combined with other criteria for matching a request by passing an options object which may have one or more of the properties described in the documentation for the options parameter.

In particular, headers, query string parameters, request bodies and express parameter values can all be used as matching criteria.

Examples​

  • {url: 'end:/user/profile', headers: {Authorization: 'Basic 123'}}
  • {query: {search: 'abc'}, method: 'POST'}