clients/tests: seed generated numbers for test-networkmanager-service.py
At several places, "test-networkmanager-service.py" uses generated numbers with a defined seed. For example, generated connection's UUID is generated in a predictable, but randomized way (if you forgive the inprecise use of the word "random" in context of using a deterministic seed). Aside the connection's UUID, this becomes more interesting in the next commit where the stub server generates a list of IP and DHCP settings in a predictable randomized way. For "clients/tests" we spawn the test service multiple times, but also create similar environments by calling init_001(). This is done for convenience, where out of lazyness all the tests share one setup. But it's still a good idea that these tests generate slightly different setups, wherever applicable. this increases the possible setups which get tested. For example, the number of static IPv4 addresses (the following commit) is interested to explicitly test for zero or a non-zero number of addresses. If all tests happen to use the same seed, the tests are expected to also generate the same number of addresses, and we miss an opportunity to hit interesting test cases. There is still no guarantee that all interesting cases are hit, the chances are just better. The approach of generating the setup randomly, does not preclude that the stub-server allows to explicitly configure the setup. However, due to the sheer number of combinations that might be interesting to test, it's much simpler to rely on some randomization and have the justifid hope we catch interesting cases. Also in terms of runtime of the test, the cli unit tests should complete within few seconds. Testing every combination would result in huge tests and long runtimes. Also, the patch refactors generating random numbers in "test-networkmanager-service.py". For example, it introduces Util.RandomSeed(), which can be used to generate a sequence of different random numbers. It works by having an internal state and a counter which is combined to chain the seed and generate different numbers on each call.
This commit is contained in:
Thomas Haller
@@ -15,11 +15,11 @@ except Exception as e:
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print("Cannot load gi.NM: %s" % (str(e)))
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sys.exit(77)
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import os
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import dbus
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import dbus.service
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import dbus.mainloop.glib
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import random
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import collections
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import uuid
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import hashlib
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import collections
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@@ -46,39 +46,111 @@ class TestError(AssertionError):
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class Util:
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class RandomSeed():
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def __init__(self, seed):
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self.cnt = 0
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self.seed = str(seed)
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def _next(self):
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c = self.cnt
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self.cnt += 1
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return self.seed + '-' + str(c)
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@staticmethod
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def wrap(seed):
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if seed is None:
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return None
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if isinstance(seed, Util.RandomSeed):
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return seed
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return Util.RandomSeed(seed)
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@staticmethod
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def get(seed, extra_seed = None):
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if seed is None:
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return None
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if isinstance(seed, Util.RandomSeed):
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seed = seed._next()
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else:
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seed = str(seed)
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if extra_seed is None:
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try:
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extra_seed = Util.RandomSeed._extra_seed
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except:
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extra_seed = os.environ.get('NM_TEST_NETWORKMANAGER_SERVICE_SEED', '')
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Util.RandomSeed._extra_seed = extra_seed
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return extra_seed + seed
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@staticmethod
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def pseudorandom_stream(seed, length = None):
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seed = str(seed)
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def random_stream(seed, length = None):
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seed = Util.RandomSeed.wrap(seed)
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# generates a stream of integers, in the range [0..255]
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if seed is None:
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# without a seed, we generate new random numbers.
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while length is None or length > 0:
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yield random.randint(0, 255)
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if length is not None:
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length -= 1
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return
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v = None
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i = 0
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while length is None or length > 0:
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if not v:
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s = seed + str(i)
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s = Util.RandomSeed.get(seed)
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s = s.encode('utf8')
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v = hashlib.sha256(s).hexdigest()
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i += 1
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yield int(v[0:2], 16)
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v = v[2:]
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if length is not None:
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length -= 1
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@staticmethod
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def pseudorandom_num(seed, v_end, v_start = 0):
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def random_int(seed, v_start = _DEFAULT_ARG, v_end = _DEFAULT_ARG):
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# - if neither start not end is give, return a number in the range
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# u32 range [0, 0xFFFFFFFF]
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# - if only start is given (the first argument), interpret it as
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# the range of the interval. That is, return random number in
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# range [0, start-1]
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# - if end and start is given, return a random number with this
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# range (inclusive!): [start, end]
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if v_end is _DEFAULT_ARG:
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# if only one edge is provided (no v_end), then the range
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# is [0, v_start[. That is, random_int(seed, 5), returns
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# values from 0 to 4.
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if v_start is _DEFAULT_ARG:
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# by default, return a 32u integer.
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v_end = 0x100000000
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else:
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v_end = v_start
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v_start = 0
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else:
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if v_start is _DEFAULT_ARG:
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raise TestError("Cannot specify end without start")
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# if a full range is provided, v_end is included.
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# random_int(seed, 0, 4) returns values from 0 to 4.
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v_end += 1
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n = 0
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span = v_end - v_start
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for r in Util.pseudorandom_stream(seed):
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assert span > 0
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for r in Util.random_stream(seed):
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n = n * 256 + r
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if n > span:
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break
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return v_start + (n % span)
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@staticmethod
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def random_mac(seed = None):
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if seed is None:
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r = tuple([random.randint(0, 255) for x in range(6)])
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else:
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r = tuple(Util.pseudorandom_stream(seed, 6))
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return '%02X:%02X:%02X:%02X:%02X:%02X' % r
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def random_bool(seed):
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return Util.random_int(seed, 0, 1) == 1
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@staticmethod
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def random_subset(seed, all_set):
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all_set = list(all_set)
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result = []
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seed = Util.RandomSeed.wrap(seed)
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for i in list(range(Util.random_int(Util.RandomSeed.get(seed), len(all_set) + 1))):
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idx = Util.random_int(Util.RandomSeed.get(seed), len(all_set))
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result.append(all_set[idx])
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del all_set[idx]
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return result
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@staticmethod
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def random_mac(seed):
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return '%02X:%02X:%02X:%02X:%02X:%02X' % tuple(Util.random_stream(seed, 6))
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@staticmethod
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def eprint(*args, **kwargs):
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@@ -643,7 +715,7 @@ class WifiAp(ExportedObj):
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if bssid is None:
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bssid = Util.random_mac(self.path)
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if strength is None:
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strength = Util.pseudorandom_num(self.path, 100)
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strength = Util.random_int(self.path, 100)
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self.ssid = ssid
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self.strength_counter = 0
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@@ -670,7 +742,7 @@ class WifiAp(ExportedObj):
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def strength_cb(self, ignored):
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self.strength_counter += 1
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strength = Util.pseudorandom_num(self.path + str(self.strength_counter), 100)
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strength = Util.random_int(self.path + str(self.strength_counter), 100)
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self._dbus_property_set(IFACE_WIFI_AP, PRP_WIFI_AP_STRENGTH, strength)
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return True
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