Delayed aka. Soft asserts for python
Few features:
- No Dependenices on any other framework/library.
- Should work with any testing framework.
- Can be use as decorator or context manager.
pip install delayed-assert pip install git+https://github.com/pr4bh4sh/delayed-assertSee tests/example_unittest.py for usage.
Pass the assertion call as
expect(lambda: self.assertListEqual([4,5,6,2,5],[7,8]))While I've tested only with unittest asserttion,It should be able to use any assertion library.
Keep in mind that, Python does not support statement inside lambda, so
expect(lambda: assert 1 == 1)won't work as it is not a valid lambda expression in python
def testSomething(self):
delayed_assert.expect(1 == 1) # will succeed
delayed_assert.expect(1 == 2) # will fail but won't stop execution
delayed_assert.expect(3 == 2, "Value don't match") # will fail but won't stop execution
delayed_assert.expect(3 == 3) # will succeed
# will stop execution and show the stack trace of 2nd assertion
delayed_assert.assert_expectations()
def testLambdas(self):
expect(lambda: self.assertEqual(3,4)) # will fail but won't stop execution
expect(lambda: self.assertListEqual([4,5,6,2,5],[7,8])) # will fail but won't stop execution
assert_expectations()
@delayed_assert.assert_all()
def testDecorator(self):
expect('five' == 'Six', 'String do not match')
expect([5,2] == [3,4], 'List item do not match')
expect([3,4] == [3,4], 'This message wont be printed')
# No need to call delayed_assert.assert_expectations() when decorator is used
def testContextManeger(self):
with delayed_assert.assert_all():
expect('four' == 'Six', 'String do not match')
expect([5,2] == [3,4], 'List item do not match')
expect([3,4] == [3,4], 'This message wont be printed')
# No need to call delayed_assert.assert_expectations() when using context maneger is used
# Use @test_case to identify helper methods or non-standard test names
@delayed_assert.test_case
def verify_something_helper(self):
expect(1 == 1)
The library supports toggling colorized output on/off via environment variable or programmatically.
# Disable colors
DELAYED_ASSERT_ENABLE_COLOR=0 python -m unittest example_unittest.py
# Enable colors (default)
DELAYED_ASSERT_ENABLE_COLOR=1 python -m unittest example_unittest.pyValues that disable colors: 0, false, no, off (case-insensitive)
from delayed_assert.delayed_assert import set_color_enabled, get_color_enabled
# Disable colors
set_color_enabled(False)
# Check status
if get_color_enabled():
print("Colors are enabled")This is useful for:
- CI/CD environments where ANSI color codes may not be supported
- Log files where color codes create noise
- Environments with accessibility requirements
By default, the library verifies that expect() is called from a method named test*.
You can disable this check if you need to use expect() in helper methods or custom test runners.
Disable via Environment Variable:
DELAYED_ASSERT_CHECK_CALLER=0 python -m unittest example_unittest.pyDisable Programmatically:
from delayed_assert.delayed_assert import set_check_caller
set_check_caller(False)Using the @test_case Decorator:
Alternatively, you can mark any function as a test case using the @test_case decorator. This allows expect() to identify the function correctly without disabling verificaton globally.
from delayed_assert import expect, assert_expectations, test_case
@test_case
def verify_custom_scenario():
expect(1 == 1, "Should pass")
def test_runner():
verify_custom_scenario()
assert_expectations()