cxxtest: preferences-test.h fails

In lp:inkscape r12423, the "testStartingState" check in preferences-test.h fails. Here is the log for "make check":

In PreferencesTest::testStartingState:
../../src/preferences-test.h:42: Error: Expected (prefs->isWritable() == false), found (true != false)

This regression seems to have been introduces in r7816 [1] when the _load() function was included in the constructor of the Preference class. Looking at the comments in bug #367752, I see that this was the source of some controversy at the time.

Without wanting to reignite any old fury... please can we look into this? I don't know about the intricacies of preference handling, but we need to either

a) change the unit test to: isWritable() == true;
b) get rid of that part of the test, or
c) change the behaviour of the Preferences object so that it is not writeable immediately after instantiation.

I'll subscribe a couple of interested parties...

[1] http://bazaar.launchpad.net/~inkscape.dev/inkscape/trunk/revision/7816#src/preferences.cpp