2021

Computer Science⚑

CICD⚑

Github Actions⚑

• New: Concurrency.

  You can use concurrency to cancel any in-progress job or run. Example:

  concurrency:
    group: docs-${{ github.head_ref }}
    cancel-in-progress: true
  

  This is useful to cancel previous jobs if new commits are pushed, which saves minutes, energy and avoids conflicts when pushing changes during the action.

Programming⚑

Basics⚑

• New: Add Flutter basics about maps.
• New: Writing Flutter documentation.

• New: Combine/merge/concat maps.

  You can use spread operator ...:

  final firstMap = {"1":"2"};
  final secondMap = {"2":"3"};
  
  final thirdMap = {
     ...firstMap,
     ...secondMap,
  };
  

• New: Find element from list.

  Use .firstWhere():

  List<Currency> currencies = ...;
  Currency dollar = currencies.firstWhere((currency) => currency.code == "USD");
  

• New: .? operator.

  Use ?. when you want to call a method/getter on an object if that object is not null (otherwise, return null).

  Example:

  currentState?.open();
  

Debugging⚑

• New: Debugging Flutter.

  Import dart:developer and add debugger(); wherever you want. Then, open your browsers developer tools and use the console.

FastAPI⚑

• New: Testing startup and shutdown events.

  When you need your event handlers (startup and shutdown) to run in your tests, you can use the TestClient with a with statement:

  import pytest
  from fastapi.testclient import TestClient
  from api.main import api
  
  @pytest.fixture
  def client():
      with TestClient(api) as client:
          yield client
  
  def test_endpoint(client):
      response = client.get("/endpoint")
  
      assert response.status_code == 200
  

pytest⚑

• New: Class fixture.

  To run a custom function for every test in a class do:

  class TestClass:
      @pytest.fixture(autouse=True)
      def setup(self):
          self.variable = 42
  
      def test_something(self):
          ...
  

Other⚑

• New: Catch only some kind of errors.

  Use @retry(retry=retry_if_exception_type(IOError)).

  Several types of exceptions can be combined as follows:

  @retry(retry=(retry_if_exception_type(IOError) | retry_if_exception_type(TimeoutError)))
  

• New: Parse hexadecimal color string.

  /// Construct a color from a hex code string, of the format #RRGGBB.
  Color hexToColor(String code) {
    return new Color(int.parse(code.substring(1, 7), radix: 16) + 0xFF000000);
  }
  

• New: Find duplicated lines.

  Also counts how many times they appear.

  sort <file> | uniq -c