Add dose 12

Author: jerry-git

code/12/pyfakefs_example.py

@@ -0,0 +1,21 @@
+import pathlib
+
+from pyfakefs.fake_filesystem import FakeFilesystem
+
+
+def my_functionality() -> None:
+    with open("foo.txt", "w") as f:
+        f.write("foo bar baz")
+
+
+# fs fixture provides a fake filesystem automatically
+def test_my_functionality(fs: FakeFilesystem) -> None:
+    path = pathlib.Path("foo.txt")
+    assert not path.exists()
+
+    my_functionality()
+
+    assert path.exists()
+    with open(path) as f:
+        content = f.read()
+    assert content == "foo bar baz"

docs/doses/12.md

@@ -0,0 +1,19 @@
+---
+title: 12 - pyfakefs
+tags:
+  - Interesting projects
+---
+# 12 - pyfakefs
+
+`pyfakefs` implements a fake filesystem which mocks the Python file system modules. Super handy for mocking file I/O in tests and comes with a built-in pytest plugin.
+
+![TODO](../img/12.png)
+
+??? info "Read more"
+    * pyfakefs GitHub: [https://github.com/jmcgeheeiv/pyfakefs/](https://github.com/jmcgeheeiv/pyfakefs/)
+    * pyfakefs docs: [http://jmcgeheeiv.github.io/pyfakefs/release/index.html](http://jmcgeheeiv.github.io/pyfakefs/release/index.html)
+
+??? tip "The code"
+    ```python
+    --8<-- "code/12/pyfakefs_example.py"
+    ```

docs/img/12.png

@@ -39,6 +39,7 @@ nav:
       - doses/9.md
       - doses/10.md
       - doses/11.md
+      - doses/12.md
 
 markdown_extensions:
   - attr_list: