fix: handle non text uploads more carefully

tests/parser/file/test_image_vision_conversion.py

@@ -0,0 +1,64 @@
+"""Re-encoding images the model providers reject (TIFF, BMP) as PNG.
+
+Chat attachments reach vision models as the stored file itself. OpenAI and
+Anthropic accept png/jpeg/webp/gif only, so a TIFF fax or a BMP screenshot has
+to be re-encoded before it can be sent at all.
+"""
+
+import io
+
+import pytest
+from PIL import Image
+
+from docsgpt.parser.file.base_parser import DocumentParseError
+from docsgpt.parser.file.image_parser import (
+    VISION_CONVERTIBLE_MIME_TYPES,
+    convert_image_to_png,
+)
+
+
+def _encoded(fmt, frames=1, size=(40, 24)):
+    """An in-memory image of ``frames`` pages, each a different red level."""
+    images = [Image.new("RGB", size, color=(i * 60, 20, 200)) for i in range(frames)]
+    buf = io.BytesIO()
+    if frames > 1:
+        images[0].save(buf, format=fmt, save_all=True, append_images=images[1:])
+    else:
+        images[0].save(buf, format=fmt)
+    buf.seek(0)
+    return buf
+
+
+@pytest.mark.unit
+class TestConvertImageToPng:
+    def test_tiff_becomes_png(self):
+        png, frames = convert_image_to_png(_encoded("TIFF"))
+
+        decoded = Image.open(io.BytesIO(png))
+        assert decoded.format == "PNG"
+        assert decoded.size == (40, 24)
+        assert frames == 1
+
+    def test_multi_page_tiff_keeps_the_first_page_and_reports_the_count(self):
+        png, frames = convert_image_to_png(_encoded("TIFF", frames=3))
+
+        decoded = Image.open(io.BytesIO(png)).convert("RGB")
+        assert frames == 3
+        assert decoded.getpixel((0, 0))[0] == 0  # page one's red level
+
+    def test_bmp_becomes_png(self):
+        png, frames = convert_image_to_png(_encoded("BMP"))
+
+        assert Image.open(io.BytesIO(png)).format == "PNG"
+        assert frames == 1
+
+    def test_unreadable_bytes_raise_a_parse_error(self):
+        with pytest.raises(DocumentParseError):
+            convert_image_to_png(io.BytesIO(b"not an image"))
+
+    def test_only_formats_the_providers_reject_are_converted(self):
+        assert {"image/tiff", "image/bmp"} <= VISION_CONVERTIBLE_MIME_TYPES
+        assert not (
+            {"image/png", "image/jpeg", "image/webp", "image/gif"}
+            & VISION_CONVERTIBLE_MIME_TYPES
+        )