Remove implementation specific tests

Author: rhpvorderman

src/zlib_ng/zlib_ngmodule.c

@@ -2768,6 +2768,18 @@ PyInit_zlib_ng(void)
     } 
     Py_INCREF(ZlibError);
     PyModule_AddObject(m, "error", ZlibError);
+
+    PyObject *gzip_module = PyImport_ImportModule("gzip");
+    if (gzip_module == NULL) {
+        return NULL;
+    }
+
+    BadGzipFile = PyObject_GetAttrString(gzip_module, "BadGzipFile");
+    if (BadGzipFile == NULL) {
+        return NULL;
+    }
+    Py_INCREF(BadGzipFile);
+
     PyModule_AddIntMacro(m, MAX_WBITS);
     PyModule_AddIntMacro(m, DEFLATED);
     PyModule_AddIntMacro(m, DEF_MEM_LEVEL);

tests/test_gzip_compliance.py

@@ -613,8 +613,7 @@ def test_read_truncated(self):
         with gzip.GzipFile(fileobj=io.BytesIO(truncated)) as f:
             self.assertRaises(EOFError, f.read)
         with gzip.GzipFile(fileobj=io.BytesIO(truncated)) as f:
-            self.assertEqual(f.read(len(data)), data)
-            self.assertRaises(EOFError, f.read, 1)
+            self.assertRaises(EOFError, f.read)
         # Incomplete 10-byte header.
         for i in range(2, 10):
             with gzip.GzipFile(fileobj=io.BytesIO(truncated[:i])) as f:
@@ -628,13 +627,6 @@ def test_read_with_extra(self):
         with gzip.GzipFile(fileobj=io.BytesIO(gzdata)) as f:
             self.assertEqual(f.read(), b'Test')
 
-    def test_prepend_error(self):
-        # See issue #20875
-        with gzip.open(self.filename, "wb") as f:
-            f.write(data1)
-        with gzip.open(self.filename, "rb") as f:
-            f._buffer.raw._fp.prepend()
-
     def test_issue44439(self):
         q = array.array('Q', [1, 2, 3, 4, 5])
         LENGTH = len(q) * q.itemsize