Test coverage.py elif branching.

test_coverage_elif_branching.py

## requirements.pip
# pytest
# pytest-cov
# black

## .coveragerc
# [run]
# branch = True
# [report]
# skip_covered = True
# skip_empty = True
# show_missing = True
# sort = Cover
# fail_under = 100

## pytest command
# pytest -rsxX -l --tb=short --strict-markers -x --cov=. --cov-config=.coveragerc

from enum import Enum


class Choices(Enum):
    ZERO = 0
    ONE = 1


def coverage_test_if(x: Choices) -> None:
    if x == Choices.ONE:
        print("One")
    else:  # This works
        print("Zero")


def coverage_test_elif(x: Choices) -> None:
    if x == Choices.ONE:
        print("One")
    elif x == Choices.ZERO:  # This doesn't work
        print("Zero")


def test_coverage_if_tests() -> None:
    assert coverage_test_elif(x=Choices.ONE) is None
    assert coverage_test_elif(x=Choices.ZERO) is None

    assert coverage_test_if(x=Choices.ONE) is None
    assert coverage_test_if(x=Choices.ZERO) is None


## Coverage report
# ---------- coverage: platform linux, python 3.10.7-final-0 -----------
# Name                 Stmts   Miss Branch BrPart  Cover   Missing
# ----------------------------------------------------------------
# test_cov_branch.py      18      0      8      1    96%   37->exit
# ----------------------------------------------------------------
# TOTAL                   18      0      8      1    96%

# FAIL Required test coverage of 100.0% not reached. Total coverage: 96.15%

Line 37 "doesn't work" because:

< nedbat> timkofu: right, because you never tested the case that line 37 was run, and the condition was false.
< nedbat> timkofu: another way to say it: line 37 is a condition that is always true