tests/test_extractimage.py: added test for pymupdf#2348.

tests/test_extractimage.py

@@ -21,3 +21,30 @@ def test_extract_image():
             image_count += 1
 
     assert image_count == known_image_count  # this number is know about the file
+
+def test_2348():
+
+    pdf_path = f'{scriptdir}/test_2348.pdf'
+    document = fitz.open()
+    page = document.new_page(width=500, height=842)
+    rect = fitz.Rect(20, 20, 480, 820)
+    page.insert_image(rect, filename=f'{scriptdir}/resources/nur-ruhig.jpg')
+    page = document.new_page(width=500, height=842)
+    page.insert_image(rect, filename=f'{scriptdir}/resources/img-transparent.png')
+    document.ez_save(pdf_path)
+    document.close()
+
+    document = fitz.open(pdf_path)
+    page = document[0]
+    imlist = page.get_images()
+    image = document.extract_image(imlist[0][0])
+    jpeg_extension = image['ext']
+
+    page = document[1]
+    imlist = page.get_images()
+    image = document.extract_image(imlist[0][0])
+    png_extension = image['ext']
+
+    print(f'jpeg_extension={jpeg_extension!r} png_extension={png_extension!r}')
+    assert jpeg_extension == 'jpeg'
+    assert png_extension == 'png'