1. DF constructor is DF(File path, long dfInterval)
- this.df = new DF(builder.getPath(), builder.getInitialUsed());
+ this.df = new DF(builder.getPath(), builder.getInterval());
2. About test. Current implementation of DF.java works on windows. And I think assertTrue(instance.getUsed() >= FILE_SIZE - 20); almost always true, since there's other files on the filesystem and other tests running. It's hard to create a mount point in the test, how about we verify that getUsed() is changing.