py3: Fix legacy_coverage test

src/calibre/db/legacy.py

@@ -70,9 +70,11 @@ class LibraryDatabase(object):
 
     def __init__(self, library_path,
             default_prefs=None, read_only=False, is_second_db=False,
-            progress_callback=lambda x, y:True, restore_all_prefs=False):
+            progress_callback=None, restore_all_prefs=False, row_factory=False):
 
         self.is_second_db = is_second_db
+        if progress_callback is None:
+            progress_callback = lambda x, y:True
         self.listeners = set()
 
         backend = self.backend = create_backend(library_path, default_prefs=default_prefs,

src/calibre/db/tests/legacy.py

@@ -37,12 +37,18 @@ class ET(object):
         return newres
 
 
+def get_defaults(spec):
+    num = len(spec.defaults or ())
+    if not num:
+        return {}
+    return dict(zip(spec.args[-num:], spec.defaults))
+
+
 def compare_argspecs(old, new, attr):
     # We dont compare the names of the non-keyword arguments as they are often
     # different and they dont affect the usage of the API.
-    num = len(old.defaults or ())
 
-    ok = len(old.args) == len(new.args) and old.defaults == new.defaults and (num == 0 or old.args[-num:] == new.args[-num:])
+    ok = len(old.args) == len(new.args) and get_defaults(old) == get_defaults(new)
     if not ok:
         raise AssertionError('The argspec for %s does not match. %r != %r' % (attr, old, new))
 
@@ -459,7 +465,7 @@ class LegacyTest(BaseTest):
                     try:
                         argspec = inspect.getargspec(obj)
                         nargspec = inspect.getargspec(nobj)
-                    except TypeError:
+                    except (TypeError, ValueError):
                         pass
                     else:
                         compare_argspecs(argspec, nargspec, attr)