Add snapshotList syntax for sequences (#25)

WoofWare.Expect/Domain.fs

@@ -1,5 +1,6 @@
 namespace WoofWare.Expect
 
+open System.Collections
 open System.Text.Json
 open System.Text.Json.Serialization
 
@@ -34,6 +35,15 @@ type ExpectState<'T> =
             Actual : (unit -> 'T) option
         }
 
+/// The state accumulated by the `expect` builder. You should never find yourself interacting with this type.
+type ExpectStateListy<'T> =
+    private
+        {
+            Formatter : ((unit -> 'T) -> string) option
+            Snapshot : (string list * CallerInfo) option
+            Actual : (unit -> 'T seq) option
+        }
+
 /// The state accumulated by the `expect` builder. You should never find yourself interacting with this type.
 type internal CompletedSnapshotGeneric<'T> =
     private
@@ -126,18 +136,69 @@ module internal CompletedSnapshotGeneric =
                 else
                     None
 
-/// Represents a snapshot test that has failed and is awaiting update or report to the user.
-type CompletedSnapshot =
-    internal
+type internal CompletedListSnapshotGeneric<'elt> =
+    private
         {
-            CallerInfo : CallerInfo
-            Replacement : string
+            Expected : string list
+            Format : 'elt -> string
+            Caller : CallerInfo
+            Actual : unit -> 'elt seq
         }
 
 [<RequireQualifiedAccess>]
-module internal CompletedSnapshot =
-    let make (s : CompletedSnapshotGeneric<'T>) =
+module internal CompletedListSnapshotGeneric =
+    let replacement (s : CompletedListSnapshotGeneric<'T>) =
+        s.Actual () |> unbox<IEnumerable> |> Seq.cast |> Seq.map s.Format |> Seq.toList
+
+    /// Returns None if the assertion passes, or Some (expected, actual) if the assertion fails.
+    let internal passesAssertion (state : CompletedListSnapshotGeneric<'T>) : (string list * string list) option =
+        let actual =
+            state.Actual ()
+            |> unbox<IEnumerable>
+            |> Seq.cast
+            |> Seq.map state.Format
+            |> Seq.toList
+
+        if state.Expected <> actual then
+            Some (state.Expected, actual)
+        else
+            None
+
+    let make (state : ExpectStateListy<'elt>) : CompletedListSnapshotGeneric<'elt> =
+        match state.Actual with
+        | None -> failwith "expected an assertion, but got none"
+        | Some actual ->
+
+        match state.Snapshot with
+        | None -> failwith "expected a snapshotList, but got none"
+        | Some (snapshot, caller) ->
+
+        let formatter =
+            match state.Formatter with
+            | Some f -> fun x -> f (fun () -> x)
+            | None -> fun x -> x.ToString ()
+
         {
-            CallerInfo = s.Caller
-            Replacement = CompletedSnapshotGeneric.replacement s
+            Expected = snapshot
+            Format = formatter
+            Caller = caller
+            Actual = actual
         }
+
+/// Represents a snapshot test that has failed and is awaiting update or report to the user.
+type internal CompletedSnapshot =
+    | GuessString of CallerInfo * replacement : string
+    | Known of CallerInfo * replacement : string list * SnapshotLocation
+
+    member this.CallerInfo =
+        match this with
+        | CompletedSnapshot.GuessString (c, _) -> c
+        | CompletedSnapshot.Known (c, _, _) -> c
+
+[<RequireQualifiedAccess>]
+module internal CompletedSnapshot =
+    let makeGuess (s : CompletedSnapshotGeneric<'T>) =
+        CompletedSnapshot.GuessString (s.Caller, CompletedSnapshotGeneric.replacement s)
+
+    let makeFromAst (source : SnapshotLocation) (s : CompletedListSnapshotGeneric<'elt>) =
+        CompletedSnapshot.Known (s.Caller, CompletedListSnapshotGeneric.replacement s, source)