Add idempotent object deletion

internal/adapters/storage/fake_test.go

@@ -71,6 +71,38 @@ func TestFakeBackendUploadAndExists(t *testing.T) {
 	}
 }
 
+func TestFakeBackendDeleteIsIdempotent(t *testing.T) {
+	fake := &FakeBackend{}
+	fake.SeedObject(FakeObject{Key: "locks/source.lock", Data: []byte("lock")})
+
+	for range 2 {
+		if err := fake.Delete(context.Background(), `locks\source.lock`); err != nil {
+			t.Fatalf("Delete() error = %v", err)
+		}
+	}
+	if _, ok := fake.Objects["locks/source.lock"]; ok {
+		t.Fatal("Delete() left the object present")
+	}
+	if len(fake.Deletes) != 2 || fake.Deletes[0] != "locks/source.lock" || fake.Deletes[1] != "locks/source.lock" {
+		t.Fatalf("Delete() calls = %#v, want two normalized keys", fake.Deletes)
+	}
+}
+
+func TestFakeBackendDeleteHonorsContextAndInjectedError(t *testing.T) {
+	canceled, cancel := context.WithCancel(context.Background())
+	cancel()
+	fake := &FakeBackend{}
+	if err := fake.Delete(canceled, "locks/source.lock"); !errors.Is(err, context.Canceled) {
+		t.Fatalf("Delete() canceled error = %v, want context.Canceled", err)
+	}
+
+	wantErr := errors.New("delete fail")
+	fake.DeleteErr = wantErr
+	if err := fake.Delete(context.Background(), "locks/source.lock"); !errors.Is(err, wantErr) {
+		t.Fatalf("Delete() injected error = %v, want %v", err, wantErr)
+	}
+}
+
 func TestFakeBackendConditionalUploadRejectsStaleGeneration(t *testing.T) {
 	fake := &FakeBackend{}
 	fake.SeedObject(FakeObject{Key: "locks.yml", Data: []byte("old")})
@@ -87,7 +119,7 @@ func TestFakeBackendConditionalUploadRejectsStaleGeneration(t *testing.T) {
 }
 
 func TestFakeBackendObjectErrors(t *testing.T) {
-	fake := &FakeBackend{DownloadErr: errors.New("download fail"), UploadErr: errors.New("upload fail"), ListErr: errors.New("list fail"), ExistsErr: errors.New("exists fail")}
+	fake := &FakeBackend{DownloadErr: errors.New("download fail"), UploadErr: errors.New("upload fail"), ListErr: errors.New("list fail"), DeleteErr: errors.New("delete fail"), ExistsErr: errors.New("exists fail")}
 
 	if _, err := fake.List(context.Background(), "x"); err == nil || !strings.Contains(err.Error(), "list fail") {
 		t.Fatalf("List() error = %v, want list fail", err)
@@ -100,6 +132,9 @@ func TestFakeBackendObjectErrors(t *testing.T) {
 	if _, err := fake.Upload(context.Background(), local, "x", UploadOptions{}); err == nil || !strings.Contains(err.Error(), "upload fail") {
 		t.Fatalf("Upload() error = %v, want upload fail", err)
 	}
+	if err := fake.Delete(context.Background(), "x"); err == nil || !strings.Contains(err.Error(), "delete fail") {
+		t.Fatalf("Delete() error = %v, want delete fail", err)
+	}
 	if _, err := fake.Exists(context.Background(), "x"); err == nil || !strings.Contains(err.Error(), "exists fail") {
 		t.Fatalf("Exists() error = %v, want exists fail", err)
 	}