test: use tempfile and auto remove it

change tools.decrpt func to use tempfile instead create a never removed
file

re6st/tests/tools.py

@@ -2,7 +2,9 @@ import sys
 import os
 import time
 import subprocess
-
+import tempfile
+import logging
+logger = logging.getLogger(__name__)
 
 with open(os.devnull, "wb") as null:
     tmp = sys.stderr
@@ -109,10 +111,15 @@ def serial2prefix(serial):
 
 # pkey: private key
 def decrypt(pkey, incontent):
-    with open("node.key", 'w') as f:
-        f.write(pkey)
-    args = "openssl rsautl -decrypt -inkey node.key".split()
-    p = subprocess.Popen(
-        args, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    fd, key_path = tempfile.mkstemp()
+    os.write(fd, pkey)
+    os.close(fd)
+    args = ['openssl', 'rsautl', '-decrypt', '-inkey', key_path]
+    p = subprocess.Popen(args, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE)
     outcontent, err = p.communicate(incontent)
+    try:
+        os.unlink(key_path)
+    except:
+        logger.error("leaked file %s", key_path)
     return outcontent