Pytest: assert almost equal

Pytest: assert almost equal

In Pytest, you can use the pytest.approx() function to assert that two floating-point numbers are almost equal within a specified tolerance. This is particularly useful when dealing with floating-point calculations that may have small variations due to numerical precision.

Here's how you can use pytest.approx() to assert almost equal values:

import pytest def test_almost_equal(): value1 = 0.1 + 0.2 value2 = 0.3 # Assert that value1 is almost equal to value2 within a tolerance of 1e-6 assert value1 == pytest.approx(value2, abs=1e-6)

In this example, we have two floating-point values, value1 and value2. We use pytest.approx() to assert that value1 is almost equal to value2 within a specified tolerance of 1e-6 (1 x 10^(-6)). If the values are within the specified tolerance, the assertion will pass; otherwise, it will fail.

You can also use pytest.approx() with relative and percentage tolerances by specifying the rel or rel_percent arguments. Here are examples:

import pytest def test_relative_tolerance(): value1 = 100.0 value2 = 101.0 # Assert that value1 is almost equal to value2 within a relative tolerance of 0.01 (1%) assert value1 == pytest.approx(value2, rel=0.01) 
import pytest def test_percentage_tolerance(): value1 = 100.0 value2 = 101.0 # Assert that value1 is almost equal to value2 within a percentage tolerance of 1% assert value1 == pytest.approx(value2, rel_percent=1.0)

These examples demonstrate how to use pytest.approx() with different tolerance types to handle floating-point comparisons in your pytest tests.

Examples

  1. "Pytest assert almost equal example"

    Description: This query aims to find examples demonstrating how to use Pytest's assertAlmostEqual assertion for comparing floating-point numbers with a specified tolerance.

    Code:

    import pytest def test_almost_equal(): # Define two floating-point numbers num1 = 0.1 + 0.2 num2 = 0.3 # Assert almost equal with tolerance of 1e-6 assert pytest.approx(num1) == num2

  2. "Pytest assertAlmostEqual usage"

    Description: This query seeks information on how to utilize Pytest's assertAlmostEqual method effectively to check approximate equality between floating-point values.

    Code:

    import pytest def test_almost_equal(): # Define two floating-point numbers num1 = 0.1 + 0.2 num2 = 0.3 # Assert almost equal with custom tolerance assert pytest.approx(num1, rel=1e-6) == num2

  3. "Pytest assert almost equal tolerance"

    Description: Users searching for this query are interested in understanding how to adjust the tolerance level when using Pytest's assertAlmostEqual assertion.

    Code:

    import pytest def test_almost_equal(): # Define two floating-point numbers num1 = 0.1 + 0.2 num2 = 0.3 # Assert almost equal with a custom tolerance of 0.01 assert pytest.approx(num1, abs=0.01) == num2

  4. "Pytest assertAlmostEqual with delta"

    Description: This query is about utilizing the assertAlmostEqual assertion in Pytest with the delta parameter to specify the allowable difference between two floating-point numbers.

    Code:

    import pytest def test_almost_equal(): # Define two floating-point numbers num1 = 0.1 + 0.2 num2 = 0.3 # Assert almost equal with delta parameter assert pytest.approx(num1, delta=1e-6) == num2

  5. "Pytest assertAlmostEqual vs assertEqual"

    Description: Users interested in this query are looking for a comparison between Pytest's assertAlmostEqual and assertEqual methods for testing floating-point numbers.

    Code:

    import pytest def test_almost_equal(): # Define two floating-point numbers num1 = 0.1 + 0.2 num2 = 0.3 # Assert almost equal using assertEqual assert num1 == pytest.approx(num2)

  6. "Pytest assertAlmostEqual for decimal numbers"

    Description: This query targets using Pytest's assertAlmostEqual assertion for comparing decimal numbers with a specified tolerance.

    Code:

    import pytest from decimal import Decimal def test_almost_equal_decimal(): # Define two decimal numbers num1 = Decimal('0.1') + Decimal('0.2') num2 = Decimal('0.3') # Assert almost equal for decimal numbers assert pytest.approx(num1, abs=0.001) == num2

  7. "Pytest assertAlmostEqual multiple tests"

    Description: Users seeking this query are interested in examples demonstrating how to use Pytest's assertAlmostEqual in multiple test cases.

    Code:

    import pytest def test_almost_equal_case1(): num1 = 0.1 + 0.2 num2 = 0.3 assert pytest.approx(num1) == num2 def test_almost_equal_case2(): num1 = 0.2 + 0.3 num2 = 0.5 assert pytest.approx(num1) == num2

  8. "Pytest assertAlmostEqual with percentage tolerance"

    Description: This query focuses on using Pytest's assertAlmostEqual with a percentage-based tolerance for comparing floating-point numbers.

    Code:

    import pytest def test_almost_equal_percentage(): # Define two floating-point numbers num1 = 100.0 num2 = 99.9 # Assert almost equal with percentage tolerance assert pytest.approx(num1, rel=0.01) == num2

  9. "Pytest assertAlmostEqual with custom tolerance"

    Description: Users searching for this query are interested in examples demonstrating how to set a custom tolerance level when using Pytest's assertAlmostEqual.

    Code:

    import pytest def test_almost_equal_custom_tolerance(): # Define two floating-point numbers num1 = 0.1 + 0.2 num2 = 0.3 # Assert almost equal with a custom tolerance of 0.0001 assert pytest.approx(num1, abs=0.0001) == num2

  10. "Pytest assert almost equal nan and infinity handling"

    Description: This query addresses how Pytest's assertAlmostEqual handles NaN and infinity values when comparing floating-point numbers.

    Code:

    import pytest import math def test_almost_equal_nan_and_inf(): # Define a NaN value and infinity nan_value = float('nan') inf_value = float('inf') # Assert almost equal for NaN and infinity assert math.isnan(pytest.approx(nan_value)) assert math.isinf(pytest.approx(inf_value))

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