docker compose entrypoint

zk/Docker_Compose_entrypoint.md

@@ -0,0 +1,30 @@
+---
+tags:
+  - docker
+---
+
+The `entrypoint` key in a Docker compose file is useful for running any advanced
+scripts before the the main `cmd` is executed.
+
+```sh
+app:
+ image: python:3.11-slim
+ entrypoint: ["./entrypoint.sh"]
+ command: ["python", "src/app.py"]
+```
+
+I used it recently to inject a `.pem` certificate into the container before the
+main execution.
+
+The script must conclude with `exec "$@"` because it receives the value of the
+`command` key in the Compose file as its argument. E.g.
+
+```sh
+cat /etc/ssl/certs/ca-certificates.crt /zscaler.pem > /tmp/combined-certs.pem
+export REQUESTS_CA_BUNDLE=/tmp/combined-certs.pem
+export SSL_CERT_FILE=/tmp/combined-certs.pem
+
+pip install -r requirements.txt
+
+exec "$@"
+```

zk/Pytest_fixtures.md

@@ -0,0 +1,88 @@
+---
+tags: [python, pytest]
+---
+
+Fixtures are a way to provide data or state to your tests. Typically, although
+not exclusively, for processes that you want to reuse accross different `test_`
+functions. They are defined at the "arrange" stage of testing.
+
+## Example: testing class methods under test
+
+```py
+class Person:
+   def __init__(self, name):
+        self.name = name
+
+   def print_name(self):
+    return f"Your name is {self.name}"
+```
+
+To create a fixture of this class:
+
+```py
+@pytest.fixture
+def my_person():
+    person = new Person('Thomas')
+    return person.name()
+
+test_print_name(my_person):
+    assert(my_person) == 'Thomas'
+
+```
+
+> Note we define our fixture and then inject it into our test function.
+> Functions request fixtures they require by declaring them as arguments.
+
+Alternatively you could just return the class from the fixture and test the
+methods individually within the test function.
+
+## Integrating with `@patch` to provide mock fixtures
+
+Say we wanted to mock reading a JSON file.
+
+We could create a fixture:
+
+```py
+
+@pytest fixture
+def raw_json():
+    return json.dumps({"key": "value"})
+```
+
+And pass it in to the mock of the global `open` method:
+
+```py
+from unittest.mock import mock_open, patch
+
+def test_json_parsing(raw_json):
+    with patch("builtins.open", mock_open(read_data=raw_json))
+        # Then assert etc
+```
+
+This fixture could then be re-used to test any other method that relies on
+incoming JSON from a file.
+
+## Example: setup and teardown - before each and after each
+
+Fixtures can be leveraged to setup 'before each...' and 'after each...' logic:
+
+```py
+@pytest.fixture(scope="function")
+def setup():
+    os.environ["POCKET_LAMBDA_ENDPOINT"] = "https://some_endpoint.com/{article_type}"
+    yield
+    del os.environ["POCKET_LAMBDA_ENDPOINT"]
+```
+
+Here `yield` is a placeholder for the tests that run in between the setup and
+teardown.
+
+We use `scope="function"` to signal that this will run before/after any tests
+that inject the fixture.
+
+Then to specify the units that will run as the `yield` we just inject `setup`:
+
+```py
+def some_function(setup_function):
+    pass
+```

zk/Testing_Python_code.md

@@ -1,18 +1,16 @@
 ---
-tags: [python, testing]
+tags: [python, testing, pytest]
 ---
 
-# Testing Python code
-
 ## `pytest`
 
 Pytest is the most popular testing library for Python. It is not included with
 the Python standard library so it must be installed with
-[pip](Python_package_management.md).
-While it does not include a declaration library, it is robust enough to handle
-most scenarios having a rich and expressive set of constructs and decorators
-that let you declare what your tests should do, under what conditions they
-should run, and how they should interact with the rest of your system.
+[pip](Python_package_management.md). While it does not include a declaration
+library, it is robust enough to handle most scenarios having a rich and
+expressive set of constructs and decorators that let you declare what your tests
+should do, under what conditions they should run, and how they should interact
+with the rest of your system.
 
 ### Using `pytest`
 

zk/Tuples_in_Python.md

@@ -2,10 +2,6 @@
 tags: [python, data-structures]
 ---
 
-# Tuples in Python
-
-TODO: Exapand tuple notes - give more use cases
-
 Tuples are one of the main data-structures or containers in Python. Tuples are
 useful in cases where you want to group related data and ensure that it will not
 change.
@@ -31,9 +27,13 @@ tup1 = (1, 3, 5, 7)
 print(tup1[2])
 
 # 5
-"""
 ```
 
+> Really you should know in advance how long your tuple is going to be but if
+> you just do `tup = ('shoe')` this will be processed by Python as a single
+> string. Instead if you want to indicate that the tuple may be expanded later
+> use `tup = ('shoe',)`. The comma converts it from a string to a tuple.
+
 ## Slicing
 
 ```python

zk/Type_hinting.md

@@ -4,8 +4,6 @@ tags:
   - data-types
 ---
 
-# Type hinting in Python
-
 With type hinting we can add type information to variables, functions, and
 classes. This is not enforced by the Python interpreter but can be used by
 external tools like `mypy` to check the code.
@@ -109,7 +107,7 @@ def find_index(numbers: list[int], target: int) -> Optional[int]:
 
 The function above returns an `int` or `None`.
 
-Post 3.10, we don't need to use `Optional`, we can use a union to cover the
+From 3.11, we don't need to use `Optional`, we can use a union to cover the
 `None` case. Refactoring the previous example:
 
 ```py