[ios] Set backup exclusion flag after initializing DefaultFileSource #5124
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Speculative fix for App Store apps backing-up the offline/ambient cache.
| [cacheURL getResourceValue:&exclusionFlag | ||
| forKey:NSURLIsExcludedFromBackupKey | ||
| error:&error]; | ||
| XCTAssertTrue([exclusionFlag boolValue], @"Backup exclusion flag should be set for cache database."); |
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Nit: check for nil before downcasting to a BOOL. Either would be a failure in this case, but this is a reminder in case we’ve made a similar assumption elsewhere.
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Which would be the runtime behavior when exclusionFlag == nil?
(lldb) po [exclusionFlag boolValue]
<nil>
(lldb) p [exclusionFlag boolValue]
(BOOL) $2 = NO
nil, no?
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When exclusionFlag is nil, [exclusionFlag boolValue] is NO, just as if exclusionFlag had been equal to @NO. By invoking the po command, you’re treating the BOOL as an object pointer and attempting to print its -description, which is nil. If we ever have to test that a boolValue is NO, either in tests or in production code, be sure to distinguish between nil and @NO.
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Added an extra check that exclusionFlag exists in 6becc07.
NSNumber could be fed some non-value that it then coerces into a boolean.
Speculatively fixes #5112, where apps mistakenly backup the offline/ambient cache.
This moves the backup exclusion flag to a point just after
DefaultFileSourcehas been created/initialized, ensuring that this flag is set on every launch.As with the other offline storage tests, the new
-testBackupExclusionmust be run in alphabetical order — or, at least after the cache has been initialized. The cache file will persist in the simulator when you run these tests locally./cc @1ec5