How to mock FileInputStream and other *Streams

Question

I have class that gets GenericFile as input argument reads data and does some additional processing. I need to test it:

public class RealCardParser {

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Answer 1

I would first extract the creation of the Stream into a dependency. So your RealCardParser gets a StreamSource as a dependency.

Now you can take appart your problem:

1. for your current test provide a mock (or in this case I would prefer a fake) implementation returning a Stream constructed from a String.

2. Test the actual StreamSource with a real file, ensuring that it returns the correct content and what not.