Bug 1460402 - Create a new class to manage pip install r=ahal

MozReview-Commit-ID: JnscCmC4gBt

--HG--
extra : rebase_source : ffd9c67d50d1ad8a9d81df3eb48ddac0ee614b6f

python/mozlint/mozlint/util/pip.py

@@ -0,0 +1,34 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import print_function
+from __future__ import absolute_import
+
+import subprocess
+
+
+def _run_pip(*args):
+    """
+    Helper function that runs pip with subprocess
+    """
+    try:
+        subprocess.check_output(['pip'] + list(args),
+                                stderr=subprocess.STDOUT)
+        return True
+    except subprocess.CalledProcessError as e:
+        print(e.output)
+        return False
+
+
+def reinstall_program(REQ_PATH):
+    """
+    Try to install flake8 at the target version, returns True on success
+    otherwise prints the otuput of the pip command and returns False
+    """
+    if _run_pip('install', '-U',
+                '--require-hashes', '-r',
+                REQ_PATH):
+        return True
+
+    return False