Found my answer. In the target dependencies, need to include the package name as a string:         // Targets are the basic building blocks of a package. A target can define a module or a test suite.         // Targets can depend on other targets in this package, and on products in packages this package depends on.         .target(             name: "DBCore",             dependencies: [ "AgileDB" ]),         .testTarget(             name: "DBCoreTests",             dependencies: ["DBCore"]),     ]