Associate parameterized fixture with parameterized test in pytest

See also questions close to this topic

• Print Variables in For Loop

  from matplotlib.pyplot import figure
  T10,T11,T12,T13 = nx.random_tree(10),nx.random_tree(11),nx.random_tree(12),nx.random_tree(13)
  T = [T10,T11,T12,T13]
  for t in T: 
      print("The Pruefer Code for -",  pruefer_code(t))
      fig = figure()
      axis = fig.add_subplot(111)
      nx.draw(t, **opts, ax = axis)
      
  

  Which results in:

  The Pruefer Code for -  [2, 8, 1, 9, 5, 5, 6, 8]
  The Pruefer Code for -  [9, 6, 10, 7, 4, 8, 10, 4, 6]
  The Pruefer Code for -  [4, 1, 4, 8, 11, 11, 8, 3, 4, 8]
  The Pruefer Code for -  [8, 7, 11, 4, 2, 7, 9, 1, 5, 10, 7]
  

  Plus the graphs - how would I amend the code so it'd say:

  The Pruefer Code for - T10 [2, 8, 1, 9, 5, 5, 6, 8]
  The Pruefer Code for - T11 [9, 6, 10, 7, 4, 8, 10, 4, 6]
  The Pruefer Code for - T12 [4, 1, 4, 8, 11, 11, 8, 3, 4, 8]
  The Pruefer Code for - T13 [8, 7, 11, 4, 2, 7, 9, 1, 5, 10, 7]
  

  Any help appreciated :)
• Get number of packets received by ping command in python

  I need a function that can return the number of packets received or loss percentage. Before I used the code below to get true/false if I receive any of the packets. This should work in Windows, but if somebody can do it suitable for Linux too, I would be thankful.

  def ping_ip(ip):
      current_os = platform.system().lower()
      parameter = "-c"
      if current_os == "windows":
          parameter = "-n"
  
      command = ['ping', parameter, '4', ip]
  
      res = subprocess.call(command)
      return res == 0
  
• Tkinter GUI unresponsive

  I'm pretty new to python and tkinter, so pardon me if I'm being naive. I'm trying to make a GUI for solving an engineering design problem using a widely accepted method (implying the method is seamless). The code for this method takes 0.537909984588623 seconds when run independently (not in tkinter but normal code), and its not too complex or tangled. When I tried to modify this code to fit into a GUI using tkinter, it becomes unresponsive after I enter all the inputs and select a button, even though the program keeps running in the background. Also, when I forcefully close the GUI window, the jupyter kernel becomes dead. Heres a brief outline of my code:

  -----------------------------------------------code begins------------------------------------------

  from tkinter import *
  from scipy.optimize import fsolve
  import matplotlib
  import numpy as np
  import threading
  from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
  from matplotlib.figure import Figure
  import matplotlib.pyplot as plt
  matplotlib.use('TkAgg')
  import math
  class MyWindow():
      def __init__(self, win):
          self.lbl1=Label(win, text='Alpha')
          self.lbl2=Label(win, text='xd')
          self.lbl3=Label(win, text='xw')
          self.lbl4=Label(win, text='xf')
          self.lbl5=Label(win, text='q')
          self.lbl6=Label(win, text='Reflux Factor')
          self.lbl7=Label(win, text='Tray Efficiency')
          self.lbl8=Label(win, text='Total Number of Stages')
          self.lbl9=Label(win, text='Feed Stage')
          
          self.t1=Entry(bd=3)
          self.t2=Entry(bd=3)
          self.t3=Entry(bd=3)
          self.t4=Entry(bd=3)
          self.t5=Entry(bd=8)
          self.t6=Entry(bd=8)
          self.t7=Entry(bd=8)
          self.t8=Entry(bd=8)
          self.t9=Entry(bd=8)
          
          self.btn1=Button(win, text='Total Number of Stages ', command=self.stagesN)
          
          self.lbl1.place(x=100, y=80)
          self.t1.place(x=300, y=80)
          self.lbl2.place(x=100, y=130)
          self.t2.place(x=300, y=130)
          self.lbl3.place(x=100, y=180)
          self.t3.place(x=300, y=180)
          self.lbl4.place(x=100, y=230)
          self.t4.place(x=300, y=230)
          self.lbl5.place(x=100, y=280)
          self.t5.place(x=300, y=280)
          self.lbl6.place(x=100, y=330)
          self.t6.place(x=300, y=330)
          self.lbl7.place(x=100, y=380)
          self.t7.place(x=300, y=380)
          self.lbl8.place(x=800, y=130)
          self.t8.place(x=790, y=170)
          self.lbl9.place(x=800, y=210)
          self.t9.place(x=790, y=260)
          self.btn1.place(x= 500, y= 75)
          
          
      def originalEq(self,xa,relative_volatility):
          ya=(relative_volatility*xa)/(1+(relative_volatility-1)*xa)
          return ya
  
      def equilibriumReal(self,xa,relative_volatility,nm):
          ya=(relative_volatility*xa)/(1+(relative_volatility-1)*xa)
          ya=((ya-xa)*nm)+xa 
          return ya
  
      def equilibriumReal2(self,ya,relative_volatility,nm):
          a=((relative_volatility*nm)-nm-relative_volatility+1)
          b=((ya*relative_volatility)-ya+nm-1-(relative_volatility*nm))
          c=ya
          xa=(-b-np.sqrt((b**2)-(4*a*c)))/(2*a) 
          return xa
      
      def stepping_ESOL(self,x1,y1,relative_volatility,R,xd,nm):
          x2=self.equilibriumReal2(y1,relative_volatility,nm) 
          y2=(((R*x2)/(R+1))+(xd/(R+1))) 
          return x1,x2,y1,y2
  
      def stepping_SSOL(self,x1,y1,relative_volatility,\
      ESOL_q_x,ESOL_q_y,xb,nm):
          x2=self.equilibriumReal2(y1,relative_volatility,nm) 
          m=((xb-ESOL_q_y)/(xb-ESOL_q_x)) 
          c=ESOL_q_y-(m*ESOL_q_x) 
          y2=(m*x2)+c 
          return x1,x2,y1,y2
  
      def stagesN(self):
          relative_volatility=float(self.t1.get())
          nm=float(self.t7.get())
          xd=float(self.t2.get())
          xb=float(self.t3.get())
          xf=float(self.t4.get())
          q=float(self.t5.get())
          R_factor=float(self.t6.get())
          
          xa=np.linspace(0,1,100) 
          ya_og=self.originalEq(xa[:],relative_volatility) 
          ya_eq=self.equilibriumReal(xa[:],relative_volatility,nm) 
  
          x_line=xa[:] 
          y_line=xa[:]
      
  
          al=relative_volatility
          a=((al*q)/(q-1))-al+(al*nm)-(q/(q-1))+1-nm
          b=(q/(q-1))-1+nm+((al*xf)/(1-q))-(xf/(1-q))-(al*nm)
          c=xf/(1-q)
  
          if q>1:
              q_eqX=(-b+np.sqrt((b**2)-(4*a*c)))/(2*a)
          else: 
              q_eqX=(-b-np.sqrt((b**2)-(4*a*c)))/(2*a)
      
          q_eqy=self.equilibriumReal(q_eqX,relative_volatility,nm)
      
  
          theta_min=xd*(1-((xd-q_eqy)/(xd-q_eqX))) 
          R_min=(xd/theta_min)-1 
          R=R_factor*R_min 
          theta=(xd/(R+1)) 
  
          ESOL_q_x=((theta-(xf/(1-q)))/((q/(q-1))-((xd-theta)/xd)))
          
          ESOL_q_y=(ESOL_q_x*((xd-theta)/xd))+theta
     
  
          x1,x2,y1,y2=self.stepping_ESOL(xd,xd,relative_volatility,R,xd,nm)
          step_count=1 
          while x2>ESOL_q_x: 
              x1,x2,y1,y2=self.stepping_ESOL(x2,y2,relative_volatility,R,xd,nm)
              step_count+=1 
              
  
          feed_stage=step_count 
      
          x1,x2,y1,y2=self.stepping_SSOL(x1,y1,relative_volatility\
          ,ESOL_q_x,ESOL_q_y,xb,nm)
          step_count+=1
          while x2>xb: 
              x1,x2,y1,y2=self.stepping_SSOL(x2,y2,relative_volatility\
              ,ESOL_q_x,ESOL_q_y,xb,nm)
              
              step_count+=1 
          xb_actual=x2 
          stagesN=step_count-1
          self.t8.insert(END, str(stagesN))
          return
          
          
          
  window=Tk()
  mywin=MyWindow(window)
  window.title('DColumn')
  window.geometry("1500x1500")
  window.mainloop()
  

  -------------------------------------------Code end--------------------------------------------

  I read on other articles that using multiple threads brings down the load on mainloop and prevents freezing. But like I said, the code isnt very complex. Is it still because of everythings running on the mainloop? Or is there something more than meets the eye? Is multithreading the only way to go past this point?

  Thanks in advance.
• Why test file can't run tests against app file?

  I'm practising tdd with Flask and funny enough my first test file can't seem to detect the main flask_app file:

  test_basics.py :

  from flask_testing import TestCase
  from flask_app import app
  import unittest
  
  
  class TestBasics(TestCase):
  
      def test_home_route(self):
          with self.client:
              response = self.client.get('/')
              self.assertEqual(response.status_code, 200)
              self.assertTrue(response.data == b'hakuna matata')
  
  if __name__ == '__main__':
      unittest.main()
  

  I created setup.py so the root directory is treated as a project directory:

  from distutils.core import setup
  from setuptools import find_packages
  
  
  setup(
      version='0.0.1',
      description='training',
      name='flask'
  )
  

  project structure:

  ├── flask_app.py
  ├── __pycache__
  │   └── flask_app.cpython-38.pyc
  ├── setup.py
  ├── tests
  │   └── test_basics.py
  └── venv
  
  
  export FLASK_APP=flask_app.py
  export FLASK_ENV=development
  flask run
  

  What do I need to do so the tests can run against the main flask_app.py file ?

  python tests/test_basics.py returns:

  ModuleNotFoundError: No module named 'flask_app'
• Unit test DAO classes with JUnit using a Connection Pool

  Hi everyone i'm new here and i need your help to unit test with junit a DAO class with a connection pool. This is the ConPool:

  public class ConPool {
  
  private static DataSource datasource;
  
  /**
   * {@return} Connection
   * {@throws} SQLException
   *     Ritorna la connessione al db.
   */
  
  public static Connection getConnection() throws SQLException {
  if (datasource == null) {
    PoolProperties p = new PoolProperties();
    p.setUrl("jdbc:mysql://localhost:3306/GameLand?serverTimezone="
            + TimeZone.getDefault().getID());
    p.setDriverClassName("com.mysql.cj.jdbc.Driver");
    p.setUsername("root");
    p.setPassword("basedidati");
    p.setMaxActive(100);
    p.setInitialSize(10);
    p.setMinIdle(10);
    p.setRemoveAbandonedTimeout(60);
    p.setRemoveAbandoned(true);
    datasource = new DataSource();
    datasource.setPoolProperties(p);
  }
    return datasource.getConnection();
   }
  }
  

  and this is the DAO class that i want to test:

  public class OrdineDAO {
  /**
   * {@return} ArrayList of Ordine.
   */
  
  public synchronized ArrayList<Ordine> doRetrieveAll() {
  
  String query = "SELECT * FROM ordine";
  ArrayList<Ordine> result = new ArrayList<Ordine>();
  
  try (Connection conn = ConPool.getConnection()) {
  
    PreparedStatement ps = conn.prepareStatement(query);
    ResultSet rs = ps.executeQuery();
    while (rs.next()) {
  
      Ordine ord = new Ordine();
      ord.setConsegnato(rs.getBoolean("consegnato"));
      ord.setDataOra(rs.getString("dataOra"));
      ord.setIdOrdine(rs.getInt("idOrdine"));
      ord.setIdProdotto(rs.getInt("idProdotto"));
      ord.setPrezzoFis(rs.getDouble("prezzoFis"));
      ord.setPrezzoDig(rs.getDouble("prezzoDig"));
      ord.setIva(rs.getDouble("iva"));
      ord.setQuantitaDigitale(rs.getInt("quantitaDigitale"));
      ord.setQuantitaFisico(rs.getInt("quantitaFisico"));
      ord.setIdUtente(rs.getInt("idUtente"));
      result.add(ord);
  
    }
  
  } catch (SQLException e) {
  
    e.printStackTrace();
  
  }
  
  
  return result;
  }
  /**
   * {@param} id: int.
   * {@return} ArrayList of Ordine.
   */
  
  public synchronized ArrayList<Ordine> doRetrieveByUser(int id) {
  
  PreparedStatement ps = null;
  String query = "SELECT * FROM ordine WHERE idUtente = ?";
  ArrayList<Ordine> result = new ArrayList<Ordine>();
  
  try (Connection conn = ConPool.getConnection()) {
  
    ps = conn.prepareStatement(query);
    ps.setInt(1, id);
    ResultSet rs = ps.executeQuery();
    while (rs.next()) {
  
      Ordine ord = new Ordine();
      ord.setConsegnato(rs.getBoolean("consegnato"));
      ord.setDataOra(rs.getString("dataOra"));
      ord.setIdOrdine(rs.getInt("idOrdine"));
      ord.setIdProdotto(rs.getInt("idProdotto"));
      ord.setPrezzoFis(rs.getDouble("prezzoFis"));
      ord.setPrezzoDig(rs.getDouble("prezzoDig"));
      ord.setIva(rs.getDouble("iva"));
      ord.setQuantitaDigitale(rs.getInt("quantitaDigitale"));
      ord.setQuantitaFisico(rs.getInt("quantitaFisico"));
      ord.setIdUtente(rs.getInt("idUtente"));
      result.add(ord);
  
    }
  
  } catch (SQLException e) {
  
    e.printStackTrace();
  
  }
  
  return result;
  }
  /**
   * {@param} data1: String.
   * {@param} data2: String.
   * {@return} ArrayList of Ordine.
   */
  
  public synchronized ArrayList<Ordine> doRetrieveByDate(String data1, String data2) {
  
  PreparedStatement ps = null;
  String query = "SELECT * FROM ordine WHERE dataOra >= ? AND dataOra <= ?";
  ArrayList<Ordine> result = new ArrayList<Ordine>();
  
  try (Connection conn = ConPool.getConnection()) {
  
    ps = conn.prepareStatement(query);
    ps.setString(1, data1);
    ps.setString(2, data2);
    ResultSet rs = ps.executeQuery();
    while (rs.next()) {
  
      Ordine ord = new Ordine();
      ord.setConsegnato(rs.getBoolean("consegnato"));
      ord.setDataOra(rs.getString("dataOra"));
      ord.setIdOrdine(rs.getInt("idOrdine"));
      ord.setIdProdotto(rs.getInt("idProdotto"));
      ord.setPrezzoFis(rs.getDouble("prezzoFis"));
      ord.setPrezzoDig(rs.getDouble("prezzoDig"));
      ord.setIva(rs.getDouble("iva"));
      ord.setQuantitaDigitale(rs.getInt("quantitaDigitale"));
      ord.setQuantitaFisico(rs.getInt("quantitaFisico"));
      ord.setIdUtente(rs.getInt("idUtente"));
      result.add(ord);
  
    }
  
  } catch (SQLException e) {
  
    e.printStackTrace();
  
  }
  
   return result;
   }
  
  }
  

  starting first with doRetrieveAll method, i tried to do a

  @Test
  public void doRetrieveAll_Success() throws SQLException {
      assertNotNull(ordineDAO.doRetrieveAll());
  }
  

  But i need to know how to set the @BeforeAll in order to test this method. Can you please help me understanding how to set properly the test class? Thank you
• NSubstitute : Can not return value of type Task`1 for IMapperBase.Map (expected type List`1)

  I write a unit test, in the test I want to test my CashCapitalService.

  in my service, I used AutoMapper for mapping my model to dto and reverse.

  My Service is:

   public class CashCapitalService : ICashCapitalService
      {
          private readonly IUnitOfWork _unitOfWork;
          private readonly IMapper _mapper;
          public CashCapitalService(IUnitOfWork unitOfWork, IMapper mapper)
          {
              _unitOfWork = unitOfWork;
              _mapper = mapper;
          }
  
          public async Task<List<CashCapitalInsertAndUpdateDto>> GetAllAsync()
          {
              var allAsync = await _unitOfWork.CashCapitalRepository.GetAllAsync();
  
              List<CashCapitalInsertAndUpdateDto> cashCapitalInsertAndUpdateDtos = _mapper.Map<List<CashCapitalInsertAndUpdateDto>>(source:allAsync);
              return cashCapitalInsertAndUpdateDtos;
          }
   public class CashCapitalService : ICashCapitalService
      {
          private readonly IUnitOfWork _unitOfWork;
          private readonly IMapper _mapper;
          public CashCapitalService(IUnitOfWork unitOfWork, IMapper mapper)
          {
              _unitOfWork = unitOfWork;
              _mapper = mapper;
          }
  
          public async Task<List<CashCapitalInsertAndUpdateDto>> GetAllAsync()
          {
              var allAsync = await _unitOfWork.CashCapitalRepository.GetAllAsync();
  
              List<CashCapitalInsertAndUpdateDto> cashCapitalInsertAndUpdateDtos = _mapper.Map<List<CashCapitalInsertAndUpdateDto>>(source:allAsync);
              return cashCapitalInsertAndUpdateDtos;
          }
  

  as you can see Automapper profile is:

  public class CashCapitalInsertDtoProfile : Profile
      {
          public CashCapitalInsertDtoProfile()
          {
              CreateMap<CashCapitalInsertAndUpdateDto, CashCapital>().ReverseMap();
          }
      }
  

  and in my unit test:

  public class CashCapitalServiceTest
      {
          private readonly CashCapitalService _cashCapitalService;
          private readonly IUnitOfWork _unitOfWork;
          private readonly IMapper _mapper;
  
          public CashCapitalServiceTest()
          {
              _unitOfWork = Substitute.For<IUnitOfWork>();
              _mapper = Substitute.For<IMapper>();
              _cashCapitalService = new CashCapitalService(_unitOfWork, _mapper);
          }
  
          [Fact]
          public async Task GetAllAsync_Should_GetAllCashCapital()
          {
              //Arrange
              _unitOfWork.CashCapitalRepository.GetAllAsync().Returns(new List<CashCapital>());
  
              var cashCapitals = new List<CashCapital>()
              {
                  new CashCapital()
                  {
                      InsertDateTime = DateTime.Now,
                      AmountRial = 250000000, 
                      Description = "tv,a lj,v"
                  }
              };
  
              var cashCapitalInsertAndUpdateDtos = new List<CashCapitalInsertAndUpdateDto>()
              {
                  new CashCapitalInsertAndUpdateDto()
                  {
                      AmountRial = 250000000, Description = "tv,a lj,v"
                  }
              };
  
  
              //var returnValue = _mapper.Map(Arg.Any<List<CashCapital>>(), Arg.Any<List<CashCapitalInsertAndUpdateDto>>());
              //_cashCapitalService.GetAllAsync().Returns(returnValue);
              _mapper.Map(cashCapitals, cashCapitalInsertAndUpdateDtos).Returns(new List<CashCapitalInsertAndUpdateDto>()
              {
                  new CashCapitalInsertAndUpdateDto()
                  {
                      AmountRial = 250000000, Description = "tv,a lj,v"
                  }
              });
              var resultValue = _mapper.Map(cashCapitals, cashCapitalInsertAndUpdateDtos);
  
              _cashCapitalService.GetAllAsync().ReturnsForAnyArgs(resultValue);
              //Act
              var all = await _cashCapitalService.GetAllAsync();
  
              //Assert
              all.Should().BeOfType<List<CashCapitalInsertAndUpdateDto>>();
              await _unitOfWork.CashCapitalRepository.Received(1).GetAllAsync();
  
          }
  }
  

  When I run this test, failed and give me an error:

  Message: NSubstitute.Exceptions.CouldNotSetReturnDueToTypeMismatchException : Can not return value of type Task1 for IMapperBase.Map (expected type List1).

  I'm new in unit testing and the NSubstitute library, I don't know how to mock the AutoMapper.
• How to pass data to a monkeypatch in pytest

  I have a simple test, where I would like to test the correct creation of the user data. The Data creation is depending on the user's week (you can consider it as a week joined). This means that users with week=2 should have all Data objects which are also have week=2. Since I have users with a different week, I want my test to cover several weeks. My problem here is that User.week is a property that uses calculations to get a real week number and I don't know how to pass the week parameter to my monkeypatch fixture to make static value be "dynamic".

  Now I have an ugly solution that works for me - I have created two the same mocks with different return values.

  test_tasks.py

  from users.tasks import create_default_data_for_user
  
  class TestUserTasks:
  
      @pytest.mark.parametrize(
          "week",
          ["mock_user_week_1", "mock_user_week_2"]
      )
      def test_create_default_data_for_user(self, user, rf, data, week):
          """
          Check creation of user data using create_default_data_for_user task.
  
          :param user: a user object fixture
          :param rf: instance of Django test RequestFactory
          :param data: fixture that creates default data object
          :param week: mock object of user's week property
          :return:
          """
  
          # Make sure the user has no user data
          assert len(user.data_set.all()) == 0
  
          create_default_data_for_user()
  
          # Now the user should be given data according to his week
          expected_user_data_count = Data.objects.filter(week=user.week).count()
  
          assert len(user.data_set.all()) == expected_user_data_count
  
          # Make sure that for the current user the second run will not cause user data duplication
          create_default_data_for_user()
          assert len(user.data_set.all()) == expected_user_data_count
  

  fixtures.py

  import pytest
  
  @pytest.fixture
  def mock_user_week_1(monkeypatch):
      """
      Mock the User object's property week.
  
      The mock object will prevent calculation of the real User's week
      and just return a given number.
      """
  
      @property
      def user_week(*args, **kwargs):
          """
          A mock object that overrides the method and returns a static value.
  
          :param args: args of the original object
          :param kwargs: kwargs of the original object
          :return: static value indicating week number 1
          """
          return 1
  
      monkeypatch.setattr(
          User,
          "week",
          user_week
      )
  
  
  @pytest.fixture
  def mock_user_week_2(monkeypatch):
      """
      Mock the User object's property week.
  
      The mock object will prevent calculation of the real User's week
      and just return a given number.
      """
  
      # pylint: disable=unused-argument
      @property
      def user_week(*args, **kwargs):
          """
          A mock object that overrides the method and returns a static value.
  
          :param args: args of the original object
          :param kwargs: kwargs of the original object
          :return: static value indicating week number 2
          """
          return 2
  
      monkeypatch.setattr(
          User,
          "week",
          user_week
      )
  
• In pytest-html plugin, capture log message for all but passed tests in report.html

  I am trying generate a html report for my pytest tests using pytest-html plugin using the below command

  pytest -v tests/ --html=report.html

  This is generating the report with log capture for all the tests but I don't want to include the logs for passed tests. Is there a way to achieve this?
• pytest stack parametrize decorators with dynamic parameters

  i'm new to pytest so please bear with me.
  i'm trying to use stack parametrize decorators to test multiple combination permutations, but the question is how can i use values from other parametrize decorators in the stack.

  i found the following: but it is not exactly what i'm looking for
  stacked parametrize
  Using fixtures in pytest.mark.parametrize\

  this is what i'm trying to achieve:

  @pytest.mark.parametrize("environment", ["main", "develop", "ci"])
  @pytest.mark.parametrize("model", get_models())
  @pytest.mark.parametrize("id", get_ids(environment, model)) #here i tried to use the returned values of environment and model from the above decorators  
  def test_ids(environment, model, id):
      another_method(environment, model, id)
      # some logic here
  

  get_ids() returns a list of ids based on a given environment and model.
  this solution doesn't work, since it raising an unresolved reference error for environment and model

  the reason that i want to use parametrize decorator is because i need to test all the permutations of environments,models and ids, but want pytest to generate a separate test for each combination.

  my current solution is:

  @pytest.mark.parametrize("environment", ["main", "develop", "ci"])
  @pytest.mark.parametrize("model", get_models())
  def test_ids(environment, model):
      ids = get_ids(environment, model)
      for id in ids:
        another_method(environment, model, id)
        # some logic here
  

  this solution works, but each test is very long since it's looping over a long list of ids, i prefer running multiple small tests, rather than fewer tests but very long.
  it makes it harder to understand what happen in the tests.
  any suggestion?
• Use a pytest fixture to download data once, but use new copies for each test

  I have test code that downloads a set of images, does some processing on them, and asserts that the processing worked as expected:

  @pytest.fixture
  def image_dir(tmp_path):
      test_imgs = [
          # ... list of img URLs
      ]
      for idx, im_url in enumerate(test_imgs):
          urllib.request.urlretrieve(im_url, tmp_path / f"{idx}.png")
      yield tmp_path
  
  def test_op_A(image_dir: Path):
      for im_path in image_dir.iterdir():
          # load the image
          # modify the image
          # save the image back to disk
  
      # assert that the modification worked as expected
  
  def test_op_B(image_dir: Path):
      for im_path in image_dir.iterdir():
          # load the image
          # modify the image
          # save the image back to disk
  
      # assert that the modification worked as expected
  
  # ... more tests with a similar format
  

  This works but is incredibly slow. I suspect that this is because the images are downloaded anew for each test.

  Is there a clean way to create the temporary directory once, cache it, and use a copy of the directory for each test? This way each test can modify the images as desired, without influencing the other tests and while remaining performant.