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Configuration​

Hi, it's mockto here again.

Remember that in introduction, I mentioned that:

We can isolate your code from the changes and uncertainty of the outside world. And we can connect your code back by a flip of a switch.

The "flip of a switch" part is where configuration comes in.

Also, you might know from incubator that mocktomata supports plugins. You can add plugins to help mocktomata to handle some specific use cases.

That is also configured in the configuration.

There are 3 ways to configure mocktomata:

Each of them can configure different settings. And when there are conflicts,

config() > Environment variables > Config file

Configuration File​

mocktomata will look for configuration in the file mocktomata.json at the root of the project, or a mocktomata section inside your package.json.

Only one of them can be used at a time. If more than one configuration are found, we will throw a AmbiguousConfig error.

Using mocktomata.json as an example, here is what can be configured and their default values:

{
  // Default: `es2015`
  "ecmaVersion": "<es2015 | es2020>",
  // Overrides the calls with `auto` mode to a specific mode.
  "overrideMode": "<live | save | simulate>",
  // Filter the calls to override using file path.
  "filePathFilter": "<regex>",
  // Filter the calls to override using spec name.
  "specNameFilter": "<regex>",
  // A list of plugins to use.
  "plugins": ["plugin-a"],
  // log level inside `mocktomata`. Default: "info"
  "logLevel": "error" | "warn" | "info" | "debug" | "trace" | "all",
  // should the log emit to console. Default: false
  "emitLog": boolean
}

Environment Variables​

Specific configuration can be overridden using environment variables. This allows different CI jobs to run mocktomata with different configuration.

  • MOCKTOMATA_MODE: overrideMode
  • MOCKTOMATA_FILE_PATH_FILTER: filePathFilter
  • MOCKTOMATA_SPEC_NAME_FILTER: specNameFilter
  • MOCKTOMATA_LOG_LEVEL: logLevel

Using config()​

Configuration can also be overridden in the runtime using the config() function.

This is useful when the configuration is stored in different means (e.g. database or remote service), or used during test startup or test runner plugins (e.g. jest watch plugins) so that the test process do not need to be restarted and do not need to manually change the configuration files.

import { config } from 'mocktomata'

config({
  ecmaVersion: "<es2015 | es2020>",
  overrideMode: "<live | save | simulate>",
  filePathFilter: "<regex>",
  specNameFilter: "<regex>",
  plugins: ["plugin-a"],
  // currently only debug level is available
  logLevel: 'debug',
  emitLog: true
})

Note the incubator has its own incubator.config() to add plugins for testing.

Tips and Tricks​

Each configuration mechanism provided is designed for a specific purpose. By using these mechanisms with their intended usage, it would be easier for you to configure mocktomata to your specific needs.

Define plugins in configuration file​

This is kind of a no-brainer. If you need a plugin, add it to mocktomata.json.

Change mode using config() function​

While you can do the same with environment variable, calling config() in a test setup file is much easier and faster.

Especially when you try to flip tests quickly.

Use Environment Variables in CI​

Environment variable based configuration is designed for CI usage.

Acceptance Tests​

Turn your tests into acceptance tests by running tests with overrideMode = 'live'.

Refresh Records​

You can easily refresh all records by running tests with overrideMode = 'save'.