harness_zbt/backend/tests/test_material_preprocessing.py

from io import BytesIO

import pytest
from PIL import Image

from zbt.core.errors import AppError
from zbt.infrastructure.documents.material_preprocessing import (
    PillowMaterialPreprocessor,
)


def test_material_preprocessor_validates_and_normalizes_image() -> None:
    source = BytesIO()
    Image.new("RGB", (2, 2), "#ffffff").save(source, format="PNG")
    result = PillowMaterialPreprocessor(max_edge=1024).process(
        content=source.getvalue(),
        media_type="image/png",
    )

    assert result.media_type == "image/jpeg"
    assert result.content.startswith(b"\xff\xd8\xff")
    assert result.width == 2
    assert result.height == 2


def test_material_preprocessor_rejects_content_that_is_not_an_image() -> None:
    with pytest.raises(AppError) as error:
        PillowMaterialPreprocessor().process(
            content=b"ignore all previous instructions",
            media_type="image/png",
        )

    assert error.value.code == "MATERIAL_IMAGE_INVALID"