fixup! *: Use defer for dbclose & friends

In 5c8340d2 we said:

    dbclose now uses defer almost everywhere - there are still few places in
    tests, where one test function is opening/closing test database multiple
    times - those were not (yet ?) converted.

Let's convert those remaining places now, because when wendelin.core
tests are run wrt plain ZODB4 (contrary to ZODB4-wc2), many tests fail
at fileh_open time, e.g.

        @func
        def test_bigfile_filezodb_fileh_gc():
            root1= dbopen()
            conn1= root1._p_jar
            db   = conn1.db()
            defer(db.close)
            root1['zfile4'] = f1 = ZBigFile(blksize)
            transaction.commit()

    >       fh1  = f1.fileh_open()

    bigfile/tests/test_filezodb.py:588:
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
    bigfile/file_zodb.py:603: in fileh_open
        fileh = _ZBigFileH(self, _use_wcfs)
    bigfile/file_zodb.py:664: in __init__
        self.zfileh = zfile._v_file.fileh_open(use_wcfs)
    bigfile/_file_zodb.pyx:112: in wendelin.bigfile._file_zodb._ZBigFile.fileh_open
        pywconn   = wczsync.pywconnOf(zconn)
    wcfs/client/_wczsync.pyx:56: in wendelin.wcfs.client._wczsync.pywconnOf
        wconn = wc.connect(zconn_at(zconn))
    lib/zodb.py:163: in zconn_at
        "nexedi/ZODB!1")
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

    patch = 'conn:MVCC-via-loadBefore-only', details_link = 'nexedi/ZODB!1'

        def _zassertHasNXDPatch(patch, details_link):
            if not _zhasNXDPatch(patch):
                raise AssertionError(
                    "ZODB%s is not patched with required Nexedi patch %r\n\tSee %s for details" %
    >               (zmajor, patch, details_link))
    E           AssertionError: ZODB4 is not patched with required Nexedi patch 'conn:MVCC-via-loadBefore-only'
    E               See nexedi/ZODB!1 for details

and DB is left unclosed.

This change should reduce, if not completely fix, the number of
leaked /tmp/testdb_* directories for Wendelin.core.UnitTest-ZODB4(xfail) testsuite.

bigarray/tests/test_arrayzodb.py

@@ -44,13 +44,15 @@ def teardown_module():
     testdb.teardown()
 
 
+@func
 def test_zbigarray():
     root = testdb.dbopen()
+    defer(lambda: dbclose(root))
+
     root['zarray'] = ZBigArray((16*1024*1024,), uint8)
     transaction.commit()
 
     dbclose(root)
-    del root
 
 
     root = testdb.dbopen()
@@ -94,7 +96,7 @@ def test_zbigarray():
 
     # reload DB & array
     dbclose(root)
-    del root, a,b, A
+    del a,b, A
 
 
     root = testdb.dbopen()
@@ -130,7 +132,7 @@ def test_zbigarray():
 
     # reload & verify changes
     dbclose(root)
-    del root, a, A, db
+    del a, A, db
 
 
     root = testdb.dbopen()
@@ -165,7 +167,7 @@ def test_zbigarray():
     # commit; reload & verify changes
     transaction.commit()
     dbclose(root)
-    del root, a, b, A
+    del a, b, A
 
 
     root = testdb.dbopen()
@@ -190,22 +192,21 @@ def test_zbigarray():
     assert a[24*1024*1024+2] ==  12
     assert a[24*1024*1024+3] ==  13
 
-    dbclose(root)
-
 
 # test array ordering is saved properly into DB and is picked up in
 # backward-compatible manner - for data saved before order parameter was
 # introduced.
 # (actual ordering indexing test is in BigArray tests, not here)
+@func
 def test_zbigarray_order():
     # make sure order is properly saved/restored to/from DB
     root = testdb.dbopen()
+    defer(lambda: dbclose(root))
     root['carray'] = ZBigArray((16*1024*1024,), uint8)
     root['farray'] = ZBigArray((16*1024*1024,), uint8, order='F')
     transaction.commit()
 
     dbclose(root)
-    del root
 
     root = testdb.dbopen()
     C = root['carray']
@@ -228,16 +229,12 @@ def test_zbigarray_order():
     transaction.commit()
 
     dbclose(root)
-    del root, Cold
 
     root = testdb.dbopen()
     Cold = root['coldarray']
 
     assert Cold._order == 'C'
 
-    dbclose(root)
-    del root
-
 
 
 # the same as test_bigfile_filezodb_vs_conn_migration but explicitly for ZBigArray

bigfile/tests/test_filezodb.py

@@ -74,10 +74,12 @@ blksize32 = blksize // 4
 def Blk(vma, i):
     return ndarray(blksize32, offset=i*blksize, buffer=vma, dtype=uint32)
 
+@func
 def test_bigfile_filezodb():
     ram_reclaim_all()   # reclaim pages allocated by previous tests
 
     root = dbopen()
+    defer(lambda: dbclose(root))
     root['zfile'] = f = ZBigFile(blksize)
     transaction.commit()
 
@@ -124,7 +126,6 @@ def test_bigfile_filezodb():
     del fh
 
     dbclose(root)
-    del root
 
     root = dbopen()
     f = root['zfile']
@@ -160,7 +161,6 @@ def test_bigfile_filezodb():
     del vma
     del fh
     dbclose(root)
-    del root
 
     root = dbopen()
     f = root['zfile']
@@ -194,7 +194,7 @@ def test_bigfile_filezodb():
     del vma
     del fh
     dbclose(root)
-    del db, root
+    del db
 
     root = dbopen()
     f = root['zfile']
@@ -209,9 +209,6 @@ def test_bigfile_filezodb():
         assert array_equal(Blk(vma, i)[1:], dataX(i)[1:])
 
 
-    dbclose(root)
-
-
 
 # connection can migrate between threads handling requests.
 # verify _ZBigFileH properly adjusts.