Parametrize with indirect fixtures in PyTest - Build an Automation Script

Test login functionality with multiple user roles using indirect fixtures

Preconditions (3)

Step 1: Use pytest.mark.parametrize to pass different user roles to the 'user' fixture indirectly

Step 2: For each user role, call the login function with credentials from the fixture

Step 3: Verify that login returns success for valid users

✅ Expected Result: The test runs for each user role, login succeeds, and assertions pass for all cases

Automation Requirements - pytest

Assertions Needed:

Assert login function returns True for each user role

Best Practices:

Use pytest.mark.parametrize with indirect=True to pass parameters to fixtures

Keep test functions simple and focused

Use fixtures to manage setup and teardown

Automated Solution

PyTest

import pytest

# Simulated login function

def login(username, password):
    valid_users = {"admin": "adminpass", "guest": "guestpass", "user": "userpass"}
    return valid_users.get(username) == password

# Fixture that receives user role indirectly
@pytest.fixture
def user(request):
    role = request.param
    credentials = {
        "admin": ("admin", "adminpass"),
        "guest": ("guest", "guestpass"),
        "user": ("user", "userpass")
    }
    return credentials[role]

# Test function using indirect parametrize
@pytest.mark.parametrize("user", ["admin", "guest", "user"], indirect=True)
def test_login(user):
    username, password = user
    assert login(username, password) is True

This code defines a login function that checks if the username and password match known valid users.

The user fixture uses request.param to receive the user role indirectly from the test parameter. It returns the corresponding credentials tuple.

The test test_login uses pytest.mark.parametrize with indirect=True to pass the user roles to the user fixture. For each role, it gets credentials and asserts that login succeeds.

This approach keeps test data separate from setup logic and makes tests clear and reusable.

Common Mistakes - 3 Pitfalls

Not using indirect=true in parametrize when passing parameters to fixtures

Hardcoding credentials inside the test instead of using fixtures

Using mutable default arguments in fixtures

Bonus Challenge

Now add data-driven testing with 3 different sets of invalid credentials to verify login fails

Show Hint

Practice

1. What does using indirect=True in @pytest.mark.parametrize do in pytest?

easy

A. It skips the test when the parameter is None.

B. It disables the fixture for that test.

C. It runs the test only once regardless of parameters.

D. It passes the parameter value to a fixture instead of directly to the test function.

Solution

1. Step 1: Understand parametrize behavior

   Normally, parameters are passed directly to the test function as arguments.

2. Step 2: Effect of indirect=True

   When indirect=True is set, pytest sends the parameter value to the fixture instead, allowing setup logic to use it.

3. Final Answer:

   It passes the parameter value to a fixture instead of directly to the test function. -> Option D

4. Quick Check:

   indirect=True means parameter goes to fixture [OK]

Hint: Indirect means parameter goes to fixture, not test directly [OK]

Common Mistakes:

• Thinking parameters always go directly to test functions
• Confusing indirect=True with skipping tests
• Assuming indirect disables fixtures

2. Which of the following is the correct syntax to parametrize a test with an indirect fixture named data for values 1 and 2, when there are other direct parameters?

easy

A. @pytest.mark.parametrize('data', [1, 2], indirect=True)

B. @pytest.mark.parametrize('data', [1, 2], indirect=['data'])

C. @pytest.mark.parametrize('data', [1, 2], indirect=False)

D. @pytest.mark.parametrize('data', [1, 2], indirect=None)

Solution

1. Step 1: Recall indirect parameter usage

   When only some parameters are indirect, you pass a list of their names to indirect.

2. Step 2: Apply to single parameter

   For one parameter data, indirect=['data'] is correct syntax.

3. Final Answer:

   @pytest.mark.parametrize('data', [1, 2], indirect=['data']) -> Option B

4. Quick Check:

   indirect=['param_name'] for indirect fixture [OK]

Hint: Use indirect=['param_name'] to mark specific params indirect [OK]

Common Mistakes:

• Using indirect=True for single param when multiple params exist
• Passing indirect=False or None which disables indirect
• Not using a list for indirect parameter names

3. Given the code below, what will be printed when running the test?

import pytest

@pytest.fixture
def data(request):
    return request.param * 2

@pytest.mark.parametrize('data', [3, 5], indirect=True)
def test_double(data):
    print(data)

medium

A. 6 and 10

B. 3 and 5

C. None and None

D. Error: request.param not found

Solution

1. Step 1: Understand fixture with request.param

   The fixture data returns request.param * 2, so it doubles the parameter.

2. Step 2: Parametrize with indirect=True

   Parameters 3 and 5 are passed to the fixture, so the test receives 6 and 10.

3. Final Answer:

   6 and 10 -> Option A

4. Quick Check:

   Fixture doubles param: 3*2=6, 5*2=10 [OK]

Hint: Indirect param goes to fixture; fixture doubles it [OK]

Common Mistakes:

• Thinking parameters go directly to test, so expecting 3 and 5
• Assuming request.param is unavailable causing error
• Confusing fixture return with test parameter

4. What is wrong with this pytest code snippet?

@pytest.fixture
def setup_data(request):
    return request.param + 1

@pytest.mark.parametrize('setup_data', [10, 20])
def test_increment(setup_data):
    assert setup_data in [11, 21]

medium

A. The fixture should not return a value.

B. Fixture name and parameter name must be different.

C. Missing indirect=True in parametrize to pass parameters to fixture.

D. The assert statement is incorrect.

Solution

1. Step 1: Check parametrize usage with fixture

   Parameters must be passed indirectly to fixtures using indirect=True.

2. Step 2: Identify missing indirect=True

   The code lacks indirect=True, so parameters go directly to test, not fixture.

3. Final Answer:

   Missing indirect=True in parametrize to pass parameters to fixture. -> Option C

4. Quick Check:

   indirect=True needed to use request.param [OK]

Hint: Add indirect=True to parametrize when using request.param [OK]

Common Mistakes:

• Forgetting indirect=True causes request.param error
• Thinking fixture and param names must differ
• Assuming fixture cannot return values

5. You want to test a fixture config that reads a file path from parameters and loads data. You have two file paths: "file1.json" and "file2.json". How do you correctly parametrize the test to pass these paths to the fixture using indirect parametrization, when there are other direct parameters?

hard

A. @pytest.mark.parametrize('config', ["file1.json", "file2.json"], indirect=['config'])

B. @pytest.mark.parametrize('config', ["file1.json", "file2.json"])

C. @pytest.mark.parametrize('config', ["file1.json", "file2.json"], indirect=True)

D. @pytest.mark.parametrize('config', ["file1.json", "file2.json"], indirect=False)

Solution

1. Step 1: Identify indirect parameter usage for single fixture

   When passing parameters to a fixture, use indirect=['fixture_name'] to mark that parameter indirect.

2. Step 2: Apply to config fixture

   Since only config is indirect, use indirect=['config'] with the list of file paths.

3. Final Answer:

   @pytest.mark.parametrize('config', ["file1.json", "file2.json"], indirect=['config']) -> Option A

4. Quick Check:

   Use indirect=['config'] to pass params to fixture [OK]

Hint: Use indirect=['fixture_name'] to pass params to fixture [OK]

Common Mistakes:

• Using indirect=True instead of list for single param
• Not using indirect causing fixture to miss parameters
• Setting indirect=False disables indirect passing