Spec.Port

Functions for working with ports during a spec.

Suppose your app sends a port command when a button is clicked, via a function called my-command-port that takes a string ("TRIGGER_REQUEST" in this case), and then displays a message received over a port subscription. You could write a scenario like so:

Spec.describe "command ports and subscription ports"
[ Spec.scenario "send and receive" (
    Spec.given (
      Spec.Setup.withInit (App.init testFlags)
        |> Spec.Setup.withUpdate App.update
        |> Spec.Setup.withView App.view
        |> Spec.Setup.withSubscriptions App.subscriptions
    )
    |> Spec.when "a message is sent out"
      [ Spec.Markup.target << by [ tag "button" ]
      , Spec.Markup.Event.click
      ]
    |> Spec.when "a response is received"
      [ Spec.Port.send "my-subscription-port" <|
          Json.Encode.object
            [ ("message", Encode.string "Have fun!")
            ]
      ]
    |> Spec.observeThat
      [ Spec.it "sent the right message over the port" (
          Spec.Port.observe "my-command-port" Json.Decode.string
            |> Spec.expect (Spec.Claim.isListWhere
              [ Spec.Claim.isEqual Debug.toString "TRIGGER_REQUEST"
              ]
            )
        )
      , Spec.it "shows the message received" (
          Spec.Markup.observeElement
            |> Spec.Markup.query << by [ id "message" ]
            |> Spec.expect (
              Spec.Claim.isSomethingWhere <|
              Spec.Markup.text <|
              Spec.Claim.isEqual Debug.toString "Have fun!"
            )
        )
      ]
  )
]

Observe Command Ports

observe : String -> Decoder a -> Observer model (List a)

Observe messages sent out via a command port.

Provide the name of the port (the function name) and a JSON decoder that can decode messages sent out over the port.

Simulate Subscription Ports

send : String -> Value -> Step model msg

A step that sends a message to a port subscription.

Provide the name of the port and an encoded JSON value that should be sent from the JavaScript side.

For example, if you have a port defined in Elm like so:

port listenForStuff : (String -> msg) -> Sub msg

Then you could send a message through this port during a scenario like so:

Spec.when "a message is sent to the subscription"
[ Json.Encode.string "Some words"
    |> Spec.Port.send "listenForStuff"
]

brian-watkins/elm-spec/3.0.1

Spec.Port

Observe Command Ports

Simulate Subscription Ports

Modules