Add multi-page TIFF test data and verification tests

Co-authored-by: cau-git <60343111+cau-git@users.noreply.github.com>

tests/test_multipage_tiff.py

@@ -0,0 +1,139 @@
+"""
+Test file for multi-page TIFF functionality.
+
+This file tests that multi-page TIFF files are properly handled by the 
+image-to-PDF conversion logic in the PDF backend.
+"""
+
+from pathlib import Path
+from PIL import Image
+
+
+def get_tiff_test_paths():
+    """Get all TIFF test files from the test data directory."""
+    directory = Path("./tests/data/tiff/")
+    if not directory.exists():
+        return []
+    
+    # List all TIFF files in the directory
+    tiff_files = sorted(directory.rglob("*.tif")) + sorted(directory.rglob("*.tiff"))
+    return tiff_files
+
+
+def test_tiff_test_files_exist():
+    """Verify that TIFF test files exist and have the expected properties."""
+    tiff_paths = get_tiff_test_paths()
+    
+    assert len(tiff_paths) > 0, "No TIFF test files found in tests/data/tiff/"
+    
+    # Expected test files
+    expected_files = {
+        "single_page.tif": 1,
+        "multipage_2pages.tif": 2,
+        "multipage_3pages.tif": 3,
+        "multipage_4pages.tif": 4,
+    }
+    
+    found_files = {p.name: p for p in tiff_paths}
+    
+    for expected_file, expected_pages in expected_files.items():
+        assert expected_file in found_files, f"Expected test file {expected_file} not found"
+        
+        # Verify the file has the expected number of pages
+        with Image.open(found_files[expected_file]) as img:
+            if hasattr(img, 'n_frames'):
+                actual_pages = img.n_frames
+            else:
+                actual_pages = 1
+                
+            assert actual_pages == expected_pages, (
+                f"File {expected_file} should have {expected_pages} pages, "
+                f"but has {actual_pages}"
+            )
+
+
+def test_multipage_tiff_image_properties():
+    """Test that our multi-page TIFF files have the correct structure."""
+    tiff_paths = get_tiff_test_paths()
+    
+    if not tiff_paths:
+        print("SKIP: No TIFF test files found")
+        return
+    
+    multipage_files = [p for p in tiff_paths if "multipage" in p.name]
+    
+    for tiff_path in multipage_files:
+        with Image.open(tiff_path) as img:
+            # Should be a multi-page image
+            assert hasattr(img, 'n_frames'), f"{tiff_path.name} should be multi-page"
+            assert img.n_frames > 1, f"{tiff_path.name} should have more than 1 frame"
+            
+            # Verify we can seek through all frames
+            frames_accessible = 0
+            try:
+                for i in range(img.n_frames):
+                    img.seek(i)
+                    frames_accessible += 1
+                    
+                    # Verify frame is valid
+                    assert img.size[0] > 0 and img.size[1] > 0, (
+                        f"Frame {i} in {tiff_path.name} has invalid size"
+                    )
+            except EOFError:
+                pass
+                
+            assert frames_accessible == img.n_frames, (
+                f"Could only access {frames_accessible} of {img.n_frames} frames "
+                f"in {tiff_path.name}"
+            )
+
+
+def test_single_page_tiff_properties():
+    """Test that single-page TIFF files have the correct structure."""
+    tiff_paths = get_tiff_test_paths()
+    
+    if not tiff_paths:
+        print("SKIP: No TIFF test files found")
+        return
+    
+    single_page_files = [p for p in tiff_paths if "single_page" in p.name]
+    
+    if not single_page_files:
+        print("SKIP: No single-page TIFF test files found")
+        return
+    
+    for tiff_path in single_page_files:
+        with Image.open(tiff_path) as img:
+            # Should be a single-page image
+            if hasattr(img, 'n_frames'):
+                assert img.n_frames == 1, f"{tiff_path.name} should have exactly 1 frame"
+            
+            # Verify image is valid
+            assert img.size[0] > 0 and img.size[1] > 0, (
+                f"{tiff_path.name} has invalid size"
+            )
+
+
+def get_expected_pages_from_filename(filename: str) -> int:
+    """Extract expected number of pages from test file names."""
+    filename_lower = filename.lower()
+    
+    if "single_page" in filename_lower:
+        return 1
+    elif "2pages" in filename_lower:
+        return 2
+    elif "3pages" in filename_lower:
+        return 3
+    elif "4pages" in filename_lower:
+        return 4
+    else:
+        # For any other files, assume single page
+        return 1
+
+
+if __name__ == "__main__":
+    # When run directly, execute the tests
+    test_tiff_test_files_exist()
+    test_multipage_tiff_image_properties()
+    test_single_page_tiff_properties()
+    print("All TIFF test file validation passed!")