feat: complete chapter 6 - testing

PhotoGroove/.gitignore

@@ -0,0 +1 @@
+elm-stuff

PhotoGroove/elm.json

@@ -23,7 +23,9 @@
         }
     },
     "test-dependencies": {
-        "direct": {},
+        "direct": {
+            "elm-explorations/test": "2.2.0"
+        },
         "indirect": {}
     }
 }

PhotoGroove/src/PhotoGroove.elm

@@ -1,20 +1,34 @@
-port module PhotoGroove exposing (main)
+port module PhotoGroove exposing
+    ( Model
+    , Msg(..)
+    , Photo
+    , Status(..)
+    , initialModel
+    , main
+    , photoDecoder
+    , photoFromUrl
+    , update
+    , urlPrefix
+    , view
+    )
 
 import Array exposing (Array)
 import Browser
 import Html exposing (..)
 import Html.Attributes as Attr exposing (class, classList, id, name, src, title, type_)
-import Html.Events exposing (onClick, on)
+import Html.Events exposing (on, onClick)
 import Http
 import Json.Decode exposing (Decoder, at, int, list, string, succeed)
 import Json.Decode.Pipeline exposing (optional, required)
 import Json.Encode
 import Random
 
+
 urlPrefix : String
 urlPrefix =
     "https://elm-in-action.com/"
 
+
 type Msg
     = ClickedPhoto String
     | SetSize ThumbnailSize
@@ -26,6 +40,7 @@ type Msg
     | SlidRipple Int
     | SlidNoise Int
 
+
 view : Model -> Html Msg
 view model =
     div [ class "content" ] <|
@@ -39,6 +54,7 @@ view model =
             Errored errorMessage ->
                 [ text ("Error: " ++ errorMessage) ]
 
+
 viewFilter : (Int -> Msg) -> String -> Int -> Html Msg
 viewFilter toMsg name magnitude =
     div [ class "filter-slider" ]
@@ -52,6 +68,7 @@ viewFilter toMsg name magnitude =
         , label [] [ text (String.fromInt magnitude) ]
         ]
 
+
 viewLoaded : List Photo -> String -> Model -> List (Html Msg)
 viewLoaded photos selectedUrl model =
     [ h1 [] [ text "Photo Groove" ]
@@ -72,6 +89,7 @@ viewLoaded photos selectedUrl model =
     , canvas [ id "main-canvas", class "large" ] []
     ]
 
+
 viewThumbnail : String -> Photo -> Html Msg
 viewThumbnail selectedUrl thumb =
     img
@@ -82,6 +100,7 @@ viewThumbnail selectedUrl thumb =
         ]
         []
 
+
 viewSizeChooser : ThumbnailSize -> Html Msg
 viewSizeChooser size =
     label []
@@ -89,35 +108,45 @@ viewSizeChooser size =
         , text (sizeToString size)
         ]
 
+
 sizeToString : ThumbnailSize -> String
 sizeToString size =
     case size of
         Small ->
             "small"
+
         Medium ->
             "medium"
+
         Large ->
             "large"
 
+
 type ThumbnailSize
     = Small
     | Medium
     | Large
 
+
 port setFilters : FilterOptions -> Cmd msg
 
+
 port activityChanges : (String -> msg) -> Sub msg
+
+
 type alias FilterOptions =
     { url : String
     , filters : List { name : String, amount : Float }
     }
 
+
 type alias Photo =
     { url : String
     , size : Int
     , title : String
     }
 
+
 photoDecoder : Decoder Photo
 photoDecoder =
     succeed Photo
@@ -125,11 +154,13 @@ photoDecoder =
         |> required "size" int
         |> optional "title" string "(untitled)"
 
+
 type Status
     = Loading
     | Loaded (List Photo) String
     | Errored String
 
+
 type alias Model =
     { status : Status
     , activity : String
@@ -139,6 +170,7 @@ type alias Model =
     , noise : Int
     }
 
+
 update : Msg -> Model -> ( Model, Cmd Msg )
 update msg model =
     case msg of
@@ -200,6 +232,7 @@ update msg model =
         SlidNoise noise ->
             applyFilters { model | noise = noise }
 
+
 applyFilters : Model -> ( Model, Cmd msg )
 applyFilters model =
     case model.status of
@@ -222,16 +255,20 @@ applyFilters model =
         Errored errorMessage ->
             ( model, Cmd.none )
 
+
 selectUrl : String -> Status -> Status
 selectUrl url status =
     case status of
         Loaded photos _ ->
             Loaded photos url
+
         Loading ->
             status
+
         Errored errorMessage ->
             status
 
+
 initialModel : Model
 initialModel =
     { status = Loading
@@ -242,6 +279,7 @@ initialModel =
     , noise = 5
     }
 
+
 initialCmd : Cmd Msg
 initialCmd =
     Http.get
@@ -249,6 +287,7 @@ initialCmd =
         , expect = Http.expectJson GotPhotos (list photoDecoder)
         }
 
+
 main : Program Float Model Msg
 main =
     Browser.element
@@ -258,6 +297,7 @@ main =
         , subscriptions = subscriptions
         }
 
+
 init : Float -> ( Model, Cmd Msg )
 init flags =
     let
@@ -266,16 +306,24 @@ init flags =
     in
     ( { initialModel | activity = activity }, initialCmd )
 
+
 subscriptions : Model -> Sub Msg
 subscriptions model =
     activityChanges GotActivity
 
+
 rangeSlider : List (Attribute msg) -> List (Html msg) -> Html msg
 rangeSlider attributes children =
     node "range-slider" attributes children
 
+
 onSlide : (Int -> msg) -> Attribute msg
 onSlide toMsg =
     at [ "detail", "userSlidTo" ] int
         |> Json.Decode.map toMsg
         |> on "slide"
+
+
+photoFromUrl : String -> Photo
+photoFromUrl url =
+    { url = url, size = 0, title = "" }

PhotoGroove/tests/PhotoGrooveTests.elm

@@ -0,0 +1,124 @@
+module PhotoGrooveTests exposing (..)
+
+import Expect exposing (Expectation)
+import Fuzz exposing (Fuzzer, int, list, string)
+import Html.Attributes as Attr exposing (src)
+import Json.Decode as Decode exposing (decodeValue)
+import Json.Encode as Encode
+import PhotoGroove
+    exposing
+        ( Model
+        , Msg(..)
+        , Photo
+        , Status(..)
+        , initialModel
+        , photoFromUrl
+        , update
+        , urlPrefix
+        , view
+        )
+import Test exposing (..)
+import Test.Html.Event as Event
+import Test.Html.Query as Query
+import Test.Html.Selector exposing (attribute, tag, text)
+
+
+decoderTest : Test
+decoderTest =
+    fuzz2 string int "title defaults to (untitled)" <|
+        \url size ->
+            [ ( "url", Encode.string url )
+            , ( "size", Encode.int size )
+            ]
+                |> Encode.object
+                |> decodeValue PhotoGroove.photoDecoder
+                |> Result.map .title
+                |> Expect.equal (Ok "(untitled)")
+
+
+sliders : Test
+sliders =
+    describe "Slider sets the desired field in the model"
+        [ testSlider "SlidHue" SlidHue .hue
+        , testSlider "SlidRipple" SlidRipple .ripple
+        , testSlider "SlidNoise" SlidNoise .noise
+        ]
+
+
+testSlider : String -> (Int -> Msg) -> (Model -> Int) -> Test
+testSlider description toMsg amountFromModel =
+    fuzz int description <|
+        \amount ->
+            initialModel
+                |> update (toMsg amount)
+                |> Tuple.first
+                |> amountFromModel
+                |> Expect.equal amount
+
+
+noPhotosNoThumbnails : Test
+noPhotosNoThumbnails =
+    test "No thumbnails render when there are no photos to render." <|
+        \_ ->
+            initialModel
+                |> PhotoGroove.view
+                |> Query.fromHtml
+                |> Query.findAll [ tag "img" ]
+                |> Query.count (Expect.equal 0)
+
+
+thumbnailRendered : String -> Query.Single msg -> Expectation
+thumbnailRendered url query =
+    query
+        |> Query.findAll [ tag "img", attribute (Attr.src (urlPrefix ++ url)) ]
+        |> Query.count (Expect.atLeast 1)
+
+
+thumbnailsWork : Test
+thumbnailsWork =
+    fuzz urlFuzzer "URLs render as thumbnail" <|
+        \urls ->
+            let
+                thumbnailChecks : List (Query.Single msg -> Expectation)
+                thumbnailChecks =
+                    List.map thumbnailRendered urls
+            in
+            { initialModel | status = Loaded (List.map photoFromUrl urls) "" }
+                |> view
+                |> Query.fromHtml
+                |> Expect.all thumbnailChecks
+
+
+urlFuzzer : Fuzzer (List String)
+urlFuzzer =
+    Fuzz.intRange 1 5
+        |> Fuzz.map urlsFromCount
+
+
+urlsFromCount : Int -> List String
+urlsFromCount urlCount =
+    List.range 1 urlCount
+        |> List.map (\num -> String.fromInt num ++ ".png")
+
+
+clickThumbnail : Test
+clickThumbnail =
+    fuzz3 urlFuzzer string urlFuzzer "clicking a thumbnail selects it" <|
+        \urlsBefore urlToSelect urlsAfter ->
+            let
+                url =
+                    urlToSelect ++ ".jpeg"
+
+                photos =
+                    (urlsBefore ++ url :: urlsAfter)
+                        |> List.map photoFromUrl
+
+                srcToClick =
+                    urlPrefix ++ url
+            in
+            { initialModel | status = Loaded photos "" }
+                |> view
+                |> Query.fromHtml
+                |> Query.find [ tag "img", attribute (Attr.src srcToClick) ]
+                |> Event.simulate Event.click
+                |> Event.expect (ClickedPhoto url)