Test environment

[sstephenson]

Provides a TestEnvironment class that helps test a Stimulus application, with methods for loading HTML fixtures, finding connected controllers, finding elements, and simulating events.

Create and stash a TestEnvironment in your test framework’s setup hook:

setup() {
  this.t = TestEnvironment.setup(document.getElementById("fixture"), {
    "expandable": ExpandableController
  })
}

And destroy it in the teardown hook:

teardown() {
  this.t.teardown()
}

Load a fixture before making assertions:

await this.t.loadFixture(`
  <div data-controller="expandable">
    <button data-action="expandable#expand">Expand</button>
  </div>
`)

Trigger a simulated click event on the button:

await this.t.triggerEvent("click", "button")

Find the connected controller instance and assert controller state:

const controller = this.t.findController("expandable")
assert.ok(controller.isExpanded)

Find elements and assert DOM state:

const element = this.t.findElement({ controller: "expandable" })
assert.ok(element.classList.has("expanded"))

[javan]

With your package.json "dist" changes, I think we can chop this down to:

"include": [
  "packages/**/*.ts"
]

[sstephenson]

Closing in favor of #58.