ready to factor slightly

thing.py

@@ -106,13 +106,15 @@ class _Node:
 def _mkbtree(records, bthKeyLen):
     nodelist = [] # append to this as we go
 
-    index_step = 8 # pointers per index node; min=2, max=11
+    # pointers per index node, range 2-11
+    index_step = 8 # not really worth tuning
 
     # First node is always a header node, with three records:
     # header records, reserved record, bitmap record
     headnode = _Node(ndType=1, ndNHeight=0, records=['header placeholder', bytes(128), 'bitmap placeholder'])
     nodelist.append(headnode)
 
+    # Followed (in our implementation) by leaf nodes
     bthNRecs = 0
     bthRoot = 0
     bthDepth = 0
@@ -158,7 +160,7 @@ def _mkbtree(records, bthKeyLen):
     # Add map nodes with 3952-bit bitmap recs to cover every node
     bits_covered = 2048
     mapnodes = []
-    while bits_covered < len(nodelist): # THIS ID NUMBER IS WRONG!
+    while bits_covered < len(nodelist):
         mapnode = _Node(ndType=2, ndNHeight=1)
         nodelist.append(mapnode)
         mapnodes.append(mapnode)

thing_test.py

@@ -22,7 +22,7 @@ def test_macos_mount():
     h.drVN = b'ElmoTest'
     hf = File()
     hf.data = b'12345' * 10
-    for i in range(100):
+    for i in reversed(range(100)):
         last = b'testfile-%03d' % i
         h[last] = hf
     ser = h.write(10*1024*1024)
@@ -32,7 +32,7 @@ def test_macos_mount():
     assert h2[b'testfile-000'].data == hf.data
 
     open('/tmp/SMALL.dmg','wb').write(ser)
-    os.system('open /tmp/SMALL.dmg')
+    os.system('hdiutil attach /tmp/SMALL.dmg')
     n = 10
     while 1:
         n += 1