Adds a new blog post about mocked object reset during test

_posts/2018-02-22-how-to-reset-a-mocked-object-during-test-python.md

@@ -0,0 +1,48 @@
+---
+title: "How to reset a mocked object during test ? - Python"
+date: 2018-02-22
+layout: post
+category: Programming
+image: /img/blog/how-to-reset-a-mocked-object-during-test-python.png
+description: "Unittest appears to be such a pain to work with... Let's see if we can figure something out !"
+---
+
+I don't know if this post title is good enough, but that is something I was facing some days ago :
+
+[![A missing blog post image](/img/blog/how-to-reset-a-mocked-object-during-test-python.png)](/img/blog/how-to-reset-a-mocked-object-during-test-python.png)
+
+The problem here can be described as below :
+
+* We'd like to mock the first (or the last ?) `Popen` call, to test the chained external calls logic
+
+* We can't mock _totally_ `Popen`, because each call would return the same thing, and this is not what we want here
+
+* There is exactly the same problem with `check_output` calls (the first one has to fail, whereas the second one should have its "default" behavior)
+
+* These calls happen during the **same tested method**, so it's not possible to reset the mock like some persons use to do :
+
+    ```python
+    p = patch("module.object", new=MagicMock(return_value="Blah"))
+    p.start()
+
+    self.assertTrue(methodToTest())
+
+    p.stop()
+
+    self.assertFalse(methodToTest())
+    ```
+
+So I've tried something, based upon [this StackOverflow thread](https://stackoverflow.com/questions/15751467/unittest-python-mock-only-one-function-multiple-call/15752019#15752019), and the result was impressive after some struggles, as expected :smirk:
+
+The idea is :
+
+* Mock the object you want to mock with a new object **you control**
+
+* This new object will behave in function of an internal state that **you set**
+
+* Decide when you want to mock this object with a "patched" entity, or let it act with its default behavior !
+
+> So let's stop endless sentences and present a **working** solution please !
+>> Yeah, you'll find below a simple use case to illustrate this principle :
+
+<script src="https://gist.github.com/HorlogeSkynet/6f41e58fa30fe3da90f9804ab5983d5e.js"></script>