Python Test Updater

Python Test Updater

Update Python tests to work correctly with new code versions.

Workflow

1. Understand the Inputs

Gather required inputs:

• Old version of Python code (file or content)
• New version of Python code (file or content)
• Old test module or test functions (file or content)

Verify inputs:

• Code files are valid Python
• Test files use pytest or unittest
• Files are readable

2. Analyze Code Changes

Automated analysis:

python scripts/analyze_code_diff.py <old_file> <new_file>

Manual analysis:

• Read both old and new code versions
• Identify what changed
• Understand the nature of changes

Identify change types:

Function signature changes:

• Added parameters
• Removed parameters
• Renamed parameters
• Changed parameter types
• Changed default values

Return value changes:

• Changed return type
• Changed return structure
• Added return fields
• Removed return fields

Behavior changes:

• Modified logic
• Changed validation rules
• Updated error handling
• Altered workflows

Class changes:

• Added/removed methods
• Modified constructor
• Changed inheritance
• Updated attributes

Async changes:

• Sync to async conversion
• Async to sync conversion

See test-update-patterns.md for detailed patterns.

3. Analyze Test Structure

Read the old tests:

• Identify test functions
• Understand test setup (fixtures, mocks)
• Note test assertions
• Check test organization

Identify test components:

• Test functions/methods
• Fixtures
• Parametrized tests
• Mocked dependencies
• Assertions

Map tests to code:

• Which tests cover which functions/classes
• What behavior each test verifies
• What assertions check what conditions

4. Determine Required Updates

For each code change, identify test impact:

Signature changes → Update function calls

# Old code: function(arg1, arg2)
# New code: function(arg1, arg2, arg3=default)

# Old test
result = function(value1, value2)

# Updated test
result = function(value1, value2)  # Works with default
# OR
result = function(value1, value2, value3)  # Explicit value

Return value changes → Update assertions

# Old code: return value
# New code: return {"result": value, "status": "ok"}

# Old test
assert result == expected_value

# Updated test
assert result["result"] == expected_value
assert result["status"] == "ok"

Behavior changes → Update expected values

# Old code: validates length >= 6
# New code: validates length >= 8 and has digit

# Old test
assert validate("abc123") == True

# Updated test
assert validate("abc12345") == True  # Updated
assert validate("abc123") == False   # Now fails

New functionality → Add new tests

# New code: added get_display_name() method

# Add new test
def test_get_display_name():
    obj = MyClass("value")
    assert obj.get_display_name() == "Value: value"

5. Update Test Code

Apply updates systematically:

Step 1: Update imports if needed

# If new exceptions or classes added
from module import NewException, NewClass

Step 2: Update function/method calls

• Add new required parameters
• Remove obsolete parameters
• Rename parameters if changed
• Update keyword arguments

Step 3: Update assertions

• Change expected values if behavior changed
• Update assertion structure if return type changed
• Add new assertions for new fields
• Remove assertions for removed fields

Step 4: Update exception handling

# Old
with pytest.raises(OldException):
    function()

# New
with pytest.raises(NewException):
    function()

Step 5: Update async/await if needed

# Old
def test_function():
    result = function()

# New (if function became async)
@pytest.mark.asyncio
async def test_function():
    result = await function()

Step 6: Add new test cases

• Test new functionality
• Test new parameters
• Test new behavior
• Test edge cases

6. Run Tests

Execute the updated tests:

# Run all tests
pytest test_file.py

# Run specific test
pytest test_file.py::test_function

# Run with verbose output
pytest -v test_file.py

Check results:

• All tests should pass
• No import errors
• No syntax errors
• No assertion failures

7. Fix Remaining Failures

If tests still fail:

Analyze error messages:

• Read the error carefully
• Identify what's failing
• Understand why it's failing

Common failure types:

1. AssertionError

AssertionError: assert 10 == 15

→ Expected value changed, update assertion

2. TypeError

TypeError: function() missing 1 required positional argument: 'new_param'

→ Add missing parameter to function call

3. AttributeError

AttributeError: 'dict' object has no attribute 'field'

→ Return type changed, update how result is accessed

4. ImportError

ImportError: cannot import name 'OldClass'

→ Class renamed or removed, update import

Fix each failure:

1. Identify the root cause
2. Apply appropriate fix
3. Re-run tests
4. Verify fix works

8. Verify and Refine

Final verification:

• All tests pass
• Test coverage maintained
• Test intent preserved
• Code quality good

Refine if needed:

• Improve test names
• Add docstrings
• Use fixtures for common setup
• Parametrize similar tests

Example refinement:

# Before
def test_function_case1():
    assert function(5) == 10

def test_function_case2():
    assert function(10) == 20

# After (parametrized)
@pytest.mark.parametrize("input,expected", [
    (5, 10),
    (10, 20),
])
def test_function(input, expected):
    assert function(input) == expected

Common Update Patterns