refactor(cache): check if file exists in load

src/Trash.Tests/Cache/ServiceCacheTest.cs

@@ -48,14 +48,13 @@ namespace Trash.Tests.Cache
         }
 
         [Test]
-        public void Load_NoFileExists_ThrowsException()
+        public void Load_NoFileExists_ReturnsNull()
         {
-            // use a real filesystem to test no file existing
-            var ctx = new Context(new FileSystem());
-
-            Action act = () => ctx.Cache.Load<ObjectWithAttribute>();
+            var ctx = new Context();
+            ctx.Filesystem.File.Exists(Arg.Any<string>()).Returns(false);
 
-            act.Should().Throw<Exception>();
+            var result = ctx.Cache.Load<ObjectWithAttribute>();
+            result.Should().BeNull();
         }
 
         [Test]
@@ -66,12 +65,14 @@ namespace Trash.Tests.Cache
             ctx.StoragePath.Path.Returns("testpath");
 
             dynamic testJson = new {TestValue = "Foo"};
+            ctx.Filesystem.File.Exists(Arg.Any<string>()).Returns(true);
             ctx.Filesystem.File.ReadAllText(Arg.Any<string>())
                 .Returns(_ => JsonConvert.SerializeObject(testJson));
 
             var obj = ctx.Cache.Load<ObjectWithAttribute>();
 
-            obj.TestValue.Should().Be("Foo");
+            obj.Should().NotBeNull();
+            obj!.TestValue.Should().Be("Foo");
             ctx.Filesystem.File.Received().ReadAllText(Path.Join("testpath", "c59d1c81", $"{ValidObjectName}.json"));
         }
 

src/Trash/Cache/IServiceCache.cs

@@ -2,7 +2,7 @@
 {
     public interface IServiceCache
     {
-        T Load<T>();
-        void Save<T>(T obj);
+        T? Load<T>() where T : class;
+        void Save<T>(T obj) where T : class;
     }
 }

src/Trash/Cache/ServiceCache.cs

@@ -13,7 +13,7 @@ namespace Trash.Cache
 {
     public class ServiceCache : IServiceCache
     {
-        private static readonly Regex AllowedObjectNameCharacters = new(@"^\w+$", RegexOptions.Compiled);
+        private static readonly Regex AllowedObjectNameCharacters = new(@"^[\w-]+$", RegexOptions.Compiled);
         private readonly IServiceConfiguration _config;
         private readonly IFileSystem _fileSystem;
         private readonly IFNV1a _hash;
@@ -27,13 +27,19 @@ namespace Trash.Cache
             _hash = FNV1aFactory.Instance.Create(FNVConfig.GetPredefinedConfig(32));
         }
 
-        public T Load<T>()
+        public T? Load<T>() where T : class
         {
-            var json = _fileSystem.File.ReadAllText(PathFromAttribute<T>());
+            var path = PathFromAttribute<T>();
+            if (!_fileSystem.File.Exists(path))
+            {
+                return null;
+            }
+
+            var json = _fileSystem.File.ReadAllText(path);
             return JObject.Parse(json).ToObject<T>();
         }
 
-        public void Save<T>(T obj)
+        public void Save<T>(T obj) where T : class
         {
             var path = PathFromAttribute<T>();
             _fileSystem.Directory.CreateDirectory(Path.GetDirectoryName(path));