test_expressions.py

import pytest

from cohortextractor.expressions import format_expression, InvalidExpressionError


def test_basic_expression_rewritting():
    output, names = format_expression(
        "foo AND (bar > 3 OR baz = 'hello')",
        name_map={
            "foo": "table1.foo",
            "bar": "table2.bar",
            "baz": "other",
            "unused": "no",
        },
        empty_value_map={"foo": 0, "bar": 0, "baz": "", "unused": ""},
    )
    assert output == "( table1.foo != 0 ) AND ( table2.bar > 3 OR other = 'hello' )"
    assert names == {"foo", "bar", "baz"}


def test_validation():
    kwargs = dict(name_map={"a": "a", "b": "b"}, empty_value_map={"a": 0, "b": 0})
    with pytest.raises(InvalidExpressionError):
        format_expression("a AND AND b", **kwargs)
    with pytest.raises(InvalidExpressionError):
        format_expression("(a AND b", **kwargs)
    with pytest.raises(InvalidExpressionError):
        format_expression("a > > b", **kwargs)


def test_validate_string():
    kwargs = dict(name_map={}, empty_value_map={})
    with pytest.raises(ValueError):
        format_expression('"no spaces"', **kwargs)
    with pytest.raises(ValueError):
        format_expression('"no$special$chars"', **kwargs)
    with pytest.raises(ValueError):
        format_expression('"all_ok_characters_but_just_a_bit_too_long"', **kwargs)
    assert format_expression('"quoted"', **kwargs)[0] == "'quoted'"
    assert format_expression('""', **kwargs)[0] == "''"