experiments.md

Experiments

"Experiments" are what Ember CLI calls Feature Toggle.

They are defined in lib/experiments/index.js. For example:

const availableExperiments = [
  'CONFIG_CACHING',
];

When a new feature is added, all supporting code and tests must be guarded to ensure all tests pass when the feature is enabled or disabled:

const { isExperimentEnabled } = require('../experiments');

// ...snip...
if (isExperimentEnabled('SOME_EXPERIMENT')) {
  ...
} else {
  ...
}

An experiment can be summarized into three different states.

Development

During active development of a feature, it can be enabled by setting the experiments related environment variable ('EMBER_CLI_' + EXPERIMENT_NAME).

For example, to enable the CONFIG_CACHING experiment mentioned in the example above while running tests you would run the following command:

EMBER_CLI_CONFIG_CACHING=true yarn test

Unsupported

The Ember CLI core team will evaluate each experiment before betas get released. If the experiment is not ready, the entry for the experiment is deleted from lib/experiments/index.js (and therefore disabled).

Supported

Once an experiment has gone through the different stages of beta, and we can confidently say a specific feature from an experiment will be supported, we delete the entry in lib/experiments/index.js and remove the experiment guards (e.g. if (experiments.FOO_BAR) {) from the codebase.