In the test mentioned above, we are checking the root Cargo.toml, this is first of all not very useful and will fail if the current folder does not contain a Cargo.toml despite having passed a proper RUNTIME_DIR that targets a runtime folder with a Cargo.toml.
https://github.com/paritytech/srtool/blob/51016485d336c6e3da8f84a29f2eadc5bbe62dc0/scripts/build#L85-L89
In the test mentioned above, we are checking the root
Cargo.toml, this is first of all not very useful and will fail if the current folder does not contain aCargo.tomldespite having passed a properRUNTIME_DIRthat targets a runtime folder with aCargo.toml.