assertTrue & assertFalse

assertTrue & assertFalse

assertTrue(expr) checks that an expression is truthy, while assertFalse(expr) checks that it is falsy. These are useful for boolean conditions and custom checks.

Basic Usage

import unittest

class TestBoolean(unittest.TestCase):
    def test_is_active(self):
        user = {"active": True}
        self.assertTrue(user["active"])

    def test_is_empty(self):
        cart = []
        self.assertFalse(len(cart) > 0)

    def test_string_truthy(self):
        self.assertTrue("non-empty string")

    def test_none_falsy(self):
        self.assertFalse(None)

    def test_zero_falsy(self):
        self.assertFalse(0)

    def test_empty_dict_falsy(self):
        self.assertFalse({})

With Custom Messages

def test_user_verified(self):
    user = get_user("alice")
    self.assertTrue(
        user.is_verified,
        f"User {user.name} should be verified"
    )

def test_payment_not_processed(self):
    order = create_order()
    self.assertFalse(
        order.is_paid,
        "Order should not be paid until confirmation"
    )

Truthy vs True

assertTrue checks for truthiness, not strict equality to True. Non-empty strings, non-zero numbers, and non-empty collections all evaluate as truthy.

self.assertTrue(1)       # passes: 1 is truthy
self.assertTrue("yes")  # passes: non-empty string
self.assertTrue([1])    # passes: non-empty list
self.assertTrue(True)   # passes: True is truthy

Key Takeaway

Use assertTrue and assertFalse to verify boolean conditions. They check truthiness, not strict identity with True/False.