@Before
  public void setUp() {
    // the HeapDisk of this file is unused; it's passed to other HeapDisks to test operations
    blocks = RegularFile.create(-1, fileTimeSource.now(), new HeapDisk(2, 2, 2));
  }
Tests for {@link HeapDisk}.

@author Colin Decker
jimfs/src/test/java/com/google/common/jimfs/HeapDiskTest.java