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39 """
40 Provides unit-testing utilities.
41
42 These utilities are kept here, separate from util.py, because they provide
43 common functionality that I do not want exported "publicly" once Cedar Backup
44 is installed on a system. They are only used for unit testing, and are only
45 useful within the source tree.
46
47 Many of these functions are in here because they are "good enough" for unit
48 test work but are not robust enough to be real public functions. Others (like
49 L{removedir}) do what they are supposed to, but I don't want responsibility for
50 making them available to others.
51
52 @sort: findResources, commandAvailable,
53 buildPath, removedir, extractTar, changeFileAge,
54 getMaskAsMode, getLogin, failUnlessAssignRaises, runningAsRoot,
55 platformMacOsX, platformWindows, platformHasEcho,
56 platformSupportsLinks, platformSupportsPermissions,
57 platformRequiresBinaryRead
58
59 @author: Kenneth J. Pronovici <pronovic@ieee.org>
60 """
61
62
63
64
65
66
67 import sys
68 import os
69 import tarfile
70 import time
71 import getpass
72 import random
73 import string
74 import platform
75 import logging
76 from StringIO import StringIO
77
78 from CedarBackup2.util import encodePath, executeCommand
79
80
81
82
83
84
85
86
87
88
90 """
91 Sets up a screen logger for debugging purposes.
92
93 Normally, the CLI functionality configures the logger so that
94 things get written to the right place. However, for debugging
95 it's sometimes nice to just get everything -- debug information
96 and output -- dumped to the screen. This function takes care
97 of that.
98 """
99 logger = logging.getLogger("CedarBackup2")
100 logger.setLevel(logging.DEBUG)
101 formatter = logging.Formatter(fmt="%(message)s")
102 handler = logging.StreamHandler(strm=sys.stdout)
103 handler.setFormatter(formatter)
104 handler.setLevel(logging.DEBUG)
105 logger.addHandler(handler)
106
107
108
109
110
111
113 """
114 Returns a dictionary of locations for various resources.
115 @param resources: List of required resources.
116 @param dataDirs: List of data directories to search within for resources.
117 @return: Dictionary mapping resource name to resource path.
118 @raise Exception: If some resource cannot be found.
119 """
120 mapping = { }
121 for resource in resources:
122 for resourceDir in dataDirs:
123 path = os.path.join(resourceDir, resource);
124 if os.path.exists(path):
125 mapping[resource] = path
126 break
127 else:
128 raise Exception("Unable to find resource [%s]." % resource)
129 return mapping
130
131
132
133
134
135
137 """
138 Indicates whether a command is available on $PATH somewhere.
139 This should work on both Windows and UNIX platforms.
140 @param command: Commang to search for
141 @return: Boolean true/false depending on whether command is available.
142 """
143 if os.environ.has_key("PATH"):
144 for path in os.environ["PATH"].split(os.sep):
145 if os.path.exists(os.path.join(path, command)):
146 return True
147 return False
148
149
150
151
152
153
155 """
156 Builds a complete path from a list of components.
157 For instance, constructs C{"/a/b/c"} from C{["/a", "b", "c",]}.
158 @param components: List of components.
159 @returns: String path constructed from components.
160 @raise ValueError: If a path cannot be encoded properly.
161 """
162 path = components[0]
163 for component in components[1:]:
164 path = os.path.join(path, component)
165 return encodePath(path)
166
167
168
169
170
171
173 """
174 Recursively removes an entire directory.
175 This is basically taken from an example on python.com.
176 @param tree: Directory tree to remove.
177 @raise ValueError: If a path cannot be encoded properly.
178 """
179 tree = encodePath(tree)
180 for root, dirs, files in os.walk(tree, topdown=False):
181 for name in files:
182 path = os.path.join(root, name)
183 if os.path.islink(path):
184 os.remove(path)
185 elif os.path.isfile(path):
186 os.remove(path)
187 for name in dirs:
188 path = os.path.join(root, name)
189 if os.path.islink(path):
190 os.remove(path)
191 elif os.path.isdir(path):
192 os.rmdir(path)
193 os.rmdir(tree)
194
195
196
197
198
199
201 """
202 Extracts the indicated tar file to the indicated tmpdir.
203 @param tmpdir: Temp directory to extract to.
204 @param filepath: Path to tarfile to extract.
205 @raise ValueError: If a path cannot be encoded properly.
206 """
207 tmpdir = encodePath(tmpdir)
208 filepath = encodePath(filepath)
209 tar = tarfile.open(filepath)
210 tar.posix = False
211 for tarinfo in tar:
212 tar.extract(tarinfo, tmpdir)
213
214
215
216
217
218
220 """
221 Changes a file age using the C{os.utime} function.
222
223 @note: Some platforms don't seem to be able to set an age precisely. As a
224 result, whereas we might have intended to set an age of 86400 seconds, we
225 actually get an age of 86399.375 seconds. When util.calculateFileAge()
226 looks at that the file, it calculates an age of 0.999992766204 days, which
227 then gets truncated down to zero whole days. The tests get very confused.
228 To work around this, I always subtract off one additional second as a fudge
229 factor. That way, the file age will be I{at least} as old as requested
230 later on.
231
232 @param filename: File to operate on.
233 @param subtract: Number of seconds to subtract from the current time.
234 @raise ValueError: If a path cannot be encoded properly.
235 """
236 filename = encodePath(filename)
237 newTime = time.time() - 1;
238 if subtract is not None:
239 newTime -= subtract
240 os.utime(filename, (newTime, newTime))
241
242
243
244
245
246
248 """
249 Returns the user's current umask inverted to a mode.
250 A mode is mostly a bitwise inversion of a mask, i.e. mask 002 is mode 775.
251 @return: Umask converted to a mode, as an integer.
252 """
253 umask = os.umask(0777)
254 os.umask(umask)
255 return int(~umask & 0777)
256
257
258
259
260
261
263 """
264 Returns the name of the currently-logged in user. This might fail under
265 some circumstances - but if it does, our tests would fail anyway.
266 """
267 return getpass.getuser()
268
269
270
271
272
273
275 """
276 Generates a random filename with the given length.
277 @param length: Length of filename.
278 @return Random filename.
279 """
280 characters = [None] * length
281 for i in xrange(length):
282 characters[i] = random.choice(string.uppercase)
283 if prefix is None:
284 prefix = ""
285 if suffix is None:
286 suffix = ""
287 return "%s%s%s" % (prefix, "".join(characters), suffix)
288
289
290
291
292
293
295 """
296 Equivalent of C{failUnlessRaises}, but used for property assignments instead.
297
298 It's nice to be able to use C{failUnlessRaises} to check that a method call
299 raises the exception that you expect. Unfortunately, this method can't be
300 used to check Python propery assignments, even though these property
301 assignments are actually implemented underneath as methods.
302
303 This function (which can be easily called by unit test classes) provides an
304 easy way to wrap the assignment checks. It's not pretty, or as intuitive as
305 the original check it's modeled on, but it does work.
306
307 Let's assume you make this method call::
308
309 testCase.failUnlessAssignRaises(ValueError, collectDir, "absolutePath", absolutePath)
310
311 If you do this, a test case failure will be raised unless the assignment::
312
313 collectDir.absolutePath = absolutePath
314
315 fails with a C{ValueError} exception. The failure message differentiates
316 between the case where no exception was raised and the case where the wrong
317 exception was raised.
318
319 @note: Internally, the C{missed} and C{instead} variables are used rather
320 than directly calling C{testCase.fail} upon noticing a problem because the
321 act of "failure" itself generates an exception that would be caught by the
322 general C{except} clause.
323
324 @param testCase: PyUnit test case object (i.e. self).
325 @param exception: Exception that is expected to be raised.
326 @param object: Object whose property is to be assigned to.
327 @param property: Name of the property, as a string.
328 @param value: Value that is to be assigned to the property.
329
330 @see: C{unittest.TestCase.failUnlessRaises}
331 """
332 missed = False
333 instead = None
334 try:
335 exec "object.%s = value" % property
336 missed = True
337 except exception: pass
338 except Exception, e: instead = e
339 if missed:
340 testCase.fail("Expected assignment to raise %s, but got no exception." % (exception.__name__))
341 if instead is not None:
342 testCase.fail("Expected assignment to raise %s, but got %s instead." % (ValueError, instead.__class__.__name__))
343
344
345
346
347
348
350 """
351 Captures the output (stdout, stderr) of a function or a method.
352
353 Some of our functions don't do anything other than just print output. We
354 need a way to test these functions (at least nominally) but we don't want
355 any of the output spoiling the test suite output.
356
357 This function just creates a dummy file descriptor that can be used as a
358 target by the callable function, rather than C{stdout} or C{stderr}.
359
360 @note: This method assumes that C{callable} doesn't take any arguments
361 besides keyword argument C{fd} to specify the file descriptor.
362
363 @param callable: Callable function or method.
364
365 @return: Output of function, as one big string.
366 """
367 fd = StringIO()
368 callable(fd=fd)
369 result = fd.getvalue()
370 fd.close()
371 return result
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467
469 """
470 Returns boolean indicating whether the effective user id is root.
471 This is always true on platforms that have no concept of root, like Windows.
472 """
473 if platformWindows():
474 return True
475 else:
476 return os.geteuid() == 0
477
478
479
480
481
482
484 """
485 Returns a list of available locales on the system
486 @return: List of string locale names
487 """
488 locales = []
489 output = executeCommand(["locale"], [ "-a", ], returnOutput=True, ignoreStderr=True)[1]
490 for line in output:
491 locales.append(line.rstrip())
492 return locales
493
494
495
496
497
498
500 """
501 Indicates whether hex float literals are allowed by the interpreter.
502
503 As far back as 2004, some Python documentation indicated that octal and hex
504 notation applies only to integer literals. However, prior to Python 2.5, it
505 was legal to construct a float with an argument like 0xAC. This check
506 provides a version-based indication of whether the current interpreter
507 supports that behavior.
508
509 This check exists so that unit tests can continue to test the same thing as
510 always for pre-2.5 interpreters (i.e. making sure backwards compatibility
511 doesn't break) while still continuing to work for later interpreters.
512
513 The returned value is True for Python <= 2.5, and False otherwise.
514 """
515 if map(int, [sys.version_info[0], sys.version_info[1]]) < [2, 5]:
516 return True
517 return False
518