robert$ ./test_for_students.py 
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1. This should print an error (or usage) message:
Usage: sync directory1 directory2
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2. This should show both dir1 and dir2 as directories:
dir1
dir2
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3. This should show sync file contents:
{
  "file1_1.txt": [
    [
      "2015-08-31 13:25:55 +1200",
      "a2ebea1d55e6059dfb7b8e8354e0233d501da9d968ad3686c49d6a443b9520a8"
    ]
  ]
}
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4. This should show two different sync files:
{
  "file1_1.txt": [
    [
      "2015-08-31 13:25:55 +1200",
      "a2ebea1d55e6059dfb7b8e8354e0233d501da9d968ad3686c49d6a443b9520a8"
    ]
  ]
}
{
  "file1_1.txt": [
    [
      "2015-08-31 13:25:55 +1200",
      "7216f4359fa78ea080f5d6ee2c13f7c2229beba4111fa339f516e3de51f4a21d"
    ],
    [
      "2015-08-31 13:25:55 +1200",
      "a2ebea1d55e6059dfb7b8e8354e0233d501da9d968ad3686c49d6a443b9520a8"
    ]
  ]
}
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5. This should show two matching directories:
-a.txt 64 2015-08-31 13:25:56 +1200
-b.txt 63 2015-08-31 13:25:56 +1200
-c.txt 63 2015-08-31 13:25:56 +1200

-a.txt 64 2015-08-31 13:25:56 +1200
-b.txt 63 2015-08-31 13:25:56 +1200
-c.txt 63 2015-08-31 13:25:56 +1200
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6. This should show two matching directories
   with the file 'a.txt' 75 bytes long
   and the modification time > 1 second later:
-a.txt 75 2015-08-31 13:25:58 +1200
-b.txt 63 2015-08-31 13:25:56 +1200
-c.txt 63 2015-08-31 13:25:56 +1200

-a.txt 75 2015-08-31 13:25:58 +1200
-b.txt 63 2015-08-31 13:25:56 +1200
-c.txt 63 2015-08-31 13:25:56 +1200
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7. This should show two pairs of matching directories
   with the second pair showing different sizes and modification times:
-a.txt 75 2015-08-31 13:26:00 +1200
-b.txt 63 2015-08-31 13:25:58 +1200
-c.txt 63 2015-08-31 13:25:58 +1200

-a.txt 75 2015-08-31 13:26:00 +1200
-b.txt 63 2015-08-31 13:25:58 +1200
-c.txt 63 2015-08-31 13:25:58 +1200

 --- then after the change ---

-a.txt 92 2015-08-31 13:26:00 +1200
-b.txt 80 2015-08-31 13:26:00 +1200
-c.txt 80 2015-08-31 13:26:00 +1200

-a.txt 92 2015-08-31 13:26:00 +1200
-b.txt 80 2015-08-31 13:26:00 +1200
-c.txt 80 2015-08-31 13:26:00 +1200
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8. This should show the two directories.
   Then they should only contain c.txt.
   Then they should have a new version of b.txt:
-a.txt 64 2015-08-31 13:26:00 +1200
-b.txt 63 2015-08-31 13:26:00 +1200
-c.txt 63 2015-08-31 13:26:00 +1200

-a.txt 64 2015-08-31 13:26:00 +1200
-b.txt 63 2015-08-31 13:26:00 +1200
-c.txt 63 2015-08-31 13:26:00 +1200

 --- only c.txt ---

-c.txt 63 2015-08-31 13:26:00 +1200

-c.txt 63 2015-08-31 13:26:00 +1200

 --- new b.txt ---

-b.txt 57 2015-08-31 13:26:00 +1200
-c.txt 63 2015-08-31 13:26:00 +1200

-b.txt 57 2015-08-31 13:26:00 +1200
-c.txt 63 2015-08-31 13:26:00 +1200
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9. This starts by showing the initial synchronized directories.
   file1_1.txt must be 81 bytes long:
-dir1_1
    -dir1_1_1
        -file1_1_1_1.txt 94 2015-08-31 13:26:01 +1200
-dir1_2
    -file1_2_1.txt 54 2015-08-31 13:26:01 +1200
-dir2_1
    -file2_1_1.txt 78 2015-08-31 13:26:01 +1200
-file1_1.txt 81 2015-08-31 13:26:03 +1200
-file1_2.txt 69 2015-08-31 13:26:01 +1200
-file2_1.txt 69 2015-08-31 13:26:01 +1200

-dir1_1
    -dir1_1_1
        -file1_1_1_1.txt 94 2015-08-31 13:26:01 +1200
-dir1_2
    -file1_2_1.txt 54 2015-08-31 13:26:01 +1200
-dir2_1
    -file2_1_1.txt 78 2015-08-31 13:26:01 +1200
-file1_1.txt 81 2015-08-31 13:26:03 +1200
-file1_2.txt 69 2015-08-31 13:26:01 +1200
-file2_1.txt 69 2015-08-31 13:26:01 +1200

 --- delete all files ---

-dir1_1
    -dir1_1_1
-dir1_2
-dir2_1

-dir1_1
    -dir1_1_1
-dir1_2
-dir2_1

 --- recreate two ---

-dir1_1
    -dir1_1_1
        -file1_1_1_1.txt 74 2015-08-31 13:26:03 +1200
-dir1_2
-dir2_1
-file1_1.txt 54 2015-08-31 13:26:03 +1200

-dir1_1
    -dir1_1_1
        -file1_1_1_1.txt 74 2015-08-31 13:26:03 +1200
-dir1_2
-dir2_1
-file1_1.txt 54 2015-08-31 13:26:03 +1200
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