Allow unit-testing in SPM builds

CoreStoreTests/BaseTestCase.swift

@@ -28,6 +28,17 @@ import XCTest
 @testable
 import CoreStore
 
+#if !SWIFT_PACKAGE
+
+extension Bundle {
+    
+    static var module: Bundle {
+        return Bundle(for: BaseTestCase.self)
+    }
+}
+
+#endif
+
 
 // MARK: - BaseTestCase
 
@@ -40,7 +51,7 @@ class BaseTestCase: XCTestCase {
         
         let stack = DataStack(
             xcodeModelName: "Model",
-            bundle: Bundle(for: Self.self)
+            bundle: Bundle.module
         )
         do {