from tests.lib import create_basic_wheel_for_package


def test_new_resolver_conflict_requirements_file(tmpdir, script):
    create_basic_wheel_for_package(script, "base", "1.0")
    create_basic_wheel_for_package(script, "base", "2.0")
    create_basic_wheel_for_package(
        script, "pkga", "1.0", depends=["base==1.0"],
    )
    create_basic_wheel_for_package(
        script, "pkgb", "1.0", depends=["base==2.0"],
    )

    req_file = tmpdir.joinpath("requirements.txt")
    req_file.write_text("pkga\npkgb")

    result = script.pip(
        "install", "--use-feature=2020-resolver",
        "--no-cache-dir", "--no-index",
        "--find-links", script.scratch_path,
        "-r", req_file,
        expect_error=True,
    )

    message = "package versions have conflicting dependencies"
    assert message in result.stderr, str(result)

Test for conflict message from requirements.txt