Sure

2.0.1 verified Mon Apr 27 auth: no python

Sure is an idiomatic assertion library for Python, designed for expressive and readable test assertions. Version 2.0.1 is current. It monkey-patches built-in types like `str`, `list`, `dict` to provide fluent assertion chains (e.g., `"hello".should.equal("hello")`). The library is in maintenance mode with sparse releases.

pip install sure

Common errors

error ModuleNotFoundError: No module named 'sure' ↓

cause Sure is not installed in the current Python environment.

fix

Run pip install sure to install the package.

error AttributeError: 'str' object has no attribute 'should' ↓

cause Sure has not been imported, so the monkey-patch has not been applied.

fix

Add import sure at the top of your test module.

error AssertionError: <some expression> should equal <value> but got <different value> ↓

cause Sure's assertion mechanism raises this custom error when a predicate fails (e.g., `.should.equal()`).

fix

Check your test logic and the actual value. This is expected behavior; handle with try/except if needed.

Warnings

gotcha sure monkey-patches built-in types globally. This can affect other libraries or test output when imported. ↓

fix Import sure only in test files or use a test runner that isolates imports. Alternatively, use sure's context manager to limit scope (not available in all versions).

deprecated The pipe syntax (e.g., `|should|`) is deprecated and may be removed in future versions. ↓

fix Use the `.should` attribute syntax instead.

breaking Python 2 support removed in v2.0. The library now requires Python 3.6+. ↓

fix Upgrade to Python 3.6+ if you are on an older version.

Imports

sure
wrong
```
from sure import *
```
correct
```
import sure
```
Wildcard import can pollute namespace and clash with builtins
sure.anything
```
from sure import anything
```
anything is a sentinel for matching any value

Quickstart

Basic usage showing .should chains and the anything sentinel.

import sure

def test_assertions():
    # Fluent assertions via monkey-patched .should
    (2 + 2).should.equal(4)
    "hello".should.contain("ell")
    [1, 2, 3].should.not_.contain(4)

    # Using anything
    from sure import anything
    "abc".should.equal(anything)

    # Assert that a function raises
    import sys
    lambda: 1/0 |should| "raise(ZeroDivisionError)"  # alternative syntax