chore: scaffold tracks and tooling

Co-Authored-By: Claude Opus 5.5 <[email protected]>

fsharp/tests/Fixtures.fs

@@ -0,0 +1,21 @@
+/// Loads shared fixtures from ../../fixtures/<name>.json.
+/// Typed decoders (point, direction, status, action, state, opt) arrive with the model (Task 13).
+module Snake.Tests.Fixtures
+
+open System.IO
+open System.Text.Json
+
+let private dir =
+    Path.GetFullPath(Path.Combine(Directory.GetCurrentDirectory(), "..", "fixtures"))
+
+let load (name: string) : JsonElement =
+    use doc = JsonDocument.Parse(File.ReadAllText(Path.Combine(dir, name + ".json")))
+    doc.RootElement.Clone()
+
+/// The cases array of a fixture.
+let cases (name: string) : JsonElement list =
+    (load name).GetProperty("cases").EnumerateArray() |> List.ofSeq
+
+/// Decode a nullable JSON value into an Option.
+let opt (f: JsonElement -> 'a) (v: JsonElement) : 'a option =
+    if v.ValueKind = JsonValueKind.Null then None else Some(f v)

fsharp/tests/M00Sanity.fs

@@ -0,0 +1,23 @@
+module Snake.Tests.M00Sanity
+
+open System.Text.Json
+open Expecto
+open Snake.Tests
+
+[<Tests>]
+let tests =
+    testList "M00 sanity" [
+        test "arithmetic" { Expect.equal (1 + 1) 2 "1 + 1" }
+
+        test "fixture loads and cases hold" {
+            Expect.equal ((Fixtures.load "m00-sanity").GetProperty("function").GetString()) "sanity" "function"
+            for c in Fixtures.cases "m00-sanity" do
+                let a = c.GetProperty("args").EnumerateArray() |> Seq.map (fun e -> e.GetInt32()) |> List.ofSeq
+                Expect.equal (List.sum a) (c.GetProperty("expected").GetInt32()) (c.GetProperty("name").GetString())
+        }
+
+        test "opt decodes null" {
+            use d = JsonDocument.Parse("null")
+            Expect.isNone (Fixtures.opt (fun e -> e.GetInt32()) d.RootElement) "null"
+        }
+    ]

fsharp/tests/Main.fs

@@ -0,0 +1,6 @@
+module Snake.Tests.Main
+
+open Expecto
+
+[<EntryPoint>]
+let main argv = runTestsInAssemblyWithCLIArgs [] argv

fsharp/tests/Snake.Tests.fsproj

@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="Fixtures.fs" />
+    <Compile Include="M00Sanity.fs" />
+    <Compile Include="Main.fs" />
+  </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Expecto" Version="11.1.1" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="../src/Snake.fsproj" />
+  </ItemGroup>
+</Project>