Add get_increased_serial function

dzonegit.py

@@ -3,6 +3,8 @@
 import sys
 import subprocess
 import re
+import time
+import datetime
 from collections import namedtuple
 from hashlib import sha256
 from pathlib import Path
@@ -100,6 +102,22 @@ def is_serial_increased(old, new):
     return 0 < diff < (2**31 - 1)
 
 
+def get_increased_serial(old):
+    """ Return increased serial number, automatically recognizing the type. """
+    old = int(old)
+    now = int(time.time())
+    todayserial = int(datetime.date.today().strftime("%Y%m%d00"))
+    if 1e9 < old < now:
+        # Serial is unix timestamp
+        return str(now)
+    elif 2e9 < old < todayserial:
+        # Serial is YYYYMMDDnn, updated before today
+        return str(todayserial)
+    else:
+        # No pattern recognized, just increase the number
+        return str(old + 1)
+
+
 def get_altered_files(against, diff_filter=None):
     """ Return list of changed files. """
     cmd = ["git", "diff", "--cached", "--name-only", "-z"]

test_dzonegit.py

@@ -1,6 +1,8 @@
 
 import pytest
 import subprocess
+import time
+import datetime
 from pathlib import Path
 
 import dzonegit
@@ -165,3 +167,11 @@ $ORIGIN dummy.
 """)
     subprocess.call(["git", "add", "dummy.zone"])
     dzonegit.check_updated_zones(dzonegit.get_head())
+
+
+def test_get_increased_serial():
+    assert "2" == dzonegit.get_increased_serial(1)
+    assert str(int(time.time())) == dzonegit.get_increased_serial(1234567890)
+    todayser = datetime.date.today().strftime("%Y%m%d00")
+    assert todayser == dzonegit.get_increased_serial("2018010100")
+    assert str(int(todayser) + 1) == dzonegit.get_increased_serial(todayser)