Fix tests

Author: StanFromIreland

Lib/zipfile/__init__.py

@@ -14,8 +14,12 @@
 import threading
 import time
 
-import zlib
-crc32 = zlib.crc32
+try:
+    import zlib
+    crc32 = zlib.crc32
+except ImportError:
+    zlib = None
+    crc32 = binascii.crc32
 
 try:
     import bz2 # We may need its compression method
@@ -767,8 +771,12 @@ def decompress(self, data):
 }
 
 def _check_compression(compression):
-    if compression in (ZIP_STORED, ZIP_DEFLATED):
+    if compression == ZIP_STORED:
         pass
+    elif compression == ZIP_DEFLATED:
+        if not zlib:
+            raise RuntimeError(
+                "Compression requires the (missing) zlib module")
     elif compression == ZIP_BZIP2:
         if not bz2:
             raise RuntimeError(