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"""Tests for torchcodec import-failure diagnostics in gr00t.utils.video_utils."""

from gr00t.utils.video_utils import _decoder_import_error


def test_ffmpeg_mismatch_message_is_actionable():
    """A native-load failure (RuntimeError) should be reported as an FFmpeg issue."""
    exc = RuntimeError(
        "Could not load libtorchcodec. Likely causes: FFmpeg is not properly "
        "installed. We support versions 4, 5, 6 and 7."
    )
    err = _decoder_import_error(exc)
    assert isinstance(err, ImportError)
    msg = str(err)
    assert "FFmpeg" in msg
    assert "FFmpeg 8" in msg
    # The original error is surfaced so the cause is not lost.
    assert "Could not load libtorchcodec" in msg


def test_oserror_is_treated_as_load_failure():
    err = _decoder_import_error(OSError("libavutil.so.60: cannot open shared object file"))
    assert isinstance(err, ImportError)
    assert "FFmpeg" in str(err)


def test_missing_package_message_points_to_install():
    """A plain ImportError means torchcodec is not installed."""
    err = _decoder_import_error(ImportError("No module named 'torchcodec'"))
    assert isinstance(err, ImportError)
    # Pin the install branch via text unique to _TORCHCODEC_INSTALL_HINT; "install"
    # alone also appears in the FFmpeg hint ("is installed", "conda install").
    assert "uv pip install torchcodec" in str(err)
    assert "native library" not in str(err)