Follow the pattern of TokenTests done for the Token struct as well as WealthsimpleAccountTests done for WealthsimpleAccount and write tests for WealthsimpleDownloader, covering as many lines and corner cases as possible.
Add the content to a new file WealthsimpleDownloaderTests, and do not include any tests which do not directly interact with WealthsimpleDownloader, e.g. just testing URLConfiguration.

For missing JSON attributes for example, not every missing attribute needs to be tested, as long as every line in the WealthsimplePosition file which handles attributes missing is covered at least once.

SwiftLint warnings and errors regarding file and class length ONLY CAN be ignored by adding the appropriate comment, all others MUST be fixed.