Add __eq__ method to Q to more easily test dynamically-built queries

[cikay]

Add __eq__ method to Q to more easily test dynamically-built queries

Description

When a query is built dynamically it is needed to be tested if it is built correctly. As query is built in a tree it is too hard to test it.

Motivation and Context

Lets say the following query is built dynamically

def build_dynamic_query():
    return (Q(firstname="John") & Q(lastname="Doe")) | Q(mother_name="Jane")

Currently to test it, the following code needs to be written which is already too complicated with just three Q objects.

def test_build_dynamic_query():
    dynamic_query = build_dynamic_query()
    expected_query = (Q(firstname="John") & Q(lastname="Doe")) | Q(mother_name="Jane")

    assert dynamic_query.join_type == expected_query.join_type
    assert dynamic_query.filters == expected_query.filters

    q1_2, q3 = expected_query.children
    expected_q3 = Q(mother_name="Jane")
    assert q1_2.join_type == Q.AND

    assert q3.join_type == expected_q3.join_type
    assert q3.filters == expected_q3.filters
    assert q3.children == expected_q3.children

    q1, q2 = q1_2.children
    expected_q2 = Q(lastname="Doe")

    assert q2.join_type == expected_q2.join_type
    assert q2.filters == expected_q2.filters
    assert q2.children == expected_q2.children

    expected_q1 = Q(firstname="John")
    assert q1.join_type == expected_q1.join_type
    assert q1.filters == expected_q1.filters
    assert q1.children == expected_q1.children

With this feature, the result will be checked against the expected value

def test_build_dynamic_query():
    dynamic_query = build_dynamic_query()
    expected_query = (Q(firstname="John") & Q(lastname="Doe")) | Q(mother_name="Jane")
    assert dynamic_query == expected_query

How Has This Been Tested?

I added tests for various queries including basic, or, and, combination of and and or.

Checklist:

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added the changelog accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[long2ice]

Thanks! Please update changelog.

[cikay]

Thanks! Please update changelog.

Done