Upgrading from V5 to V6

This is a long overdue refactor of the entire library. As feature requests have come in, the code and test suite had become increasingly spaghettified, and this new version is a massive improvement on the previous implementation.

For the most common use cases, and the basic mocking and inspecting api, very little has changed. The main changes are around how fetch-mock is configured and installed, and turning a few nice new features on by default (couldn’t do so in v5 as would’ve been a breaking change)

Changes

Configuration and installation

• Requires async / await - for older node versions use v5, or require the transpiled version: require('fetch-mock/es5/server')
• No change to mocking fetch as a global
• Uses whatever version of node-fetch you have already installed in your project i.e. can be used with node-fetch 2
• .sandbox() no longer accepts a custom Promise implementation as a parameter
• Sandboxes can now be ‘sub-classed’ i.e. define some mocks on a sandbox, then call .sandbox() on it to create a new one inheriting all its settings
• No longer has a setImplementations() method. Instead, assign custom Promise and fetch helper classes directly to the config property of the fetch-mock instance. This may be done before or after sandboxing
• No longer has a configure() method. Instead set options directly on the .config property. See the api docs for a complete list of options

Routing

• ^ is no longer a valid way of matching the beginning of strings; use begin: instead
• overwriteRoutes option allows for existing routes in a mock to be overwritten. It’s also possible to define multiple routes with ‘the same’ matcher. Default behaviour is to error. Set to false to use old “buffer-like” behavior

Responses

• Content-Length header generated by default for all responses (can be configured to not do so globally or per response.)
• Objects will be converted to JSON responses if they contain any properties not listed in the docs as special response config options (previous behaviour was to convert if any of the properties were present). This means that e.g. {user: 'me', status: 'happy'} can easily be sent as JSON
• __redirectUrl option is now named redirectUrl
• times option is now named repeat

Inspecting

• All inspection methods now filter, in addition to the existing check against matcher.toString(), based on the following rules
  • An exact url
  • true for matched calls only
  • false for unmatched calls only
  • undefined (or no argument) includes all calls to fetch in order in a single array, i.e. no longer an object with matched and unmatched properties
• When fetch was last called with a Request object, lastUrl() and lastOpts() give easier access to the url and full Request object