CheckAntagonisticRead checks an external storage is able to perform reads if the HTTP client's dialer artificially degrades its connections.

CheckExportStore runs an array of tests against a store.

CheckExportStoreSkipSingleFile runs an array of tests against a store, skipping single file tests.

CheckListFiles tests the ListFiles() interface method for the ExternalStorage specified by storeURI.

CheckListFilesCanonical is like CheckListFiles but takes a canonical prefix that it should expect to see on returned listings, instead of storeURI (e.g.

CheckNoPermission checks that we do not have permission to list the external storage at storeURI.

IsImplicitAuthConfigured returns true if the `GOOGLE_APPLICATION_CREDENTIALS` environment variable is set.

EConnRefused is the conn refused err used by the antagonisticDialer.