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| """ | |
| tests/test_background.py | |
| -------------------------- | |
| Tests for border-connected background detection. | |
| Run with: pytest tests/test_background.py -v | |
| """ | |
| import sys | |
| from pathlib import Path | |
| import numpy as np | |
| sys.path.insert(0, str(Path(__file__).resolve().parent.parent)) | |
| from background import apply_transparency, detect_background | |
| def test_black_background_detected(): | |
| rgba = np.zeros((20, 20, 4), dtype=np.uint8) | |
| rgba[:, :, 3] = 255 | |
| bg = detect_background(rgba) | |
| assert bg.color[:3] == (0, 0, 0) | |
| assert bg.is_transparent is False | |
| def test_interior_black_pixel_is_not_marked_background(): | |
| """ | |
| CRITICAL RULE: a sprite drawn on a black background can have its own | |
| black pixels (e.g. an outline). Only background pixels reachable from | |
| the sheet border are background -- an enclosed black pixel inside a | |
| sprite must never be marked as background. | |
| """ | |
| rgba = np.zeros((20, 20, 4), dtype=np.uint8) | |
| rgba[:, :, 3] = 255 | |
| rgba[5:15, 5:15] = [200, 50, 50, 255] # red sprite body | |
| rgba[9, 9] = [0, 0, 0, 255] # black pixel INSIDE the sprite | |
| bg = detect_background(rgba) | |
| assert bg.mask[9, 9] == False # noqa: E712 -- must not be flagged as background | |
| assert bg.mask[0, 0] == True # noqa: E712 -- the actual border IS background | |
| def test_apply_transparency_preserves_interior_pixel(): | |
| rgba = np.zeros((20, 20, 4), dtype=np.uint8) | |
| rgba[:, :, 3] = 255 | |
| rgba[5:15, 5:15] = [200, 50, 50, 255] | |
| rgba[9, 9] = [0, 0, 0, 255] | |
| bg = detect_background(rgba) | |
| out = apply_transparency(rgba, bg) | |
| assert out[9, 9, 3] == 255 # interior black pixel: untouched | |
| assert out[0, 0, 3] == 0 # border background pixel: made transparent | |
| assert tuple(out[9, 9, :3]) == (0, 0, 0) # color also untouched | |
| def test_already_transparent_sheet_detected_as_transparent_background(): | |
| rgba = np.zeros((20, 20, 4), dtype=np.uint8) # fully transparent | |
| rgba[5:15, 5:15] = [80, 180, 90, 255] # opaque sprite in the middle | |
| bg = detect_background(rgba) | |
| assert bg.is_transparent is True | |
| assert bg.mask[0, 0] == True # noqa: E712 | |
| def test_white_background_detected(): | |
| rgba = np.full((20, 20, 4), 255, dtype=np.uint8) | |
| rgba[5:15, 5:15] = [10, 10, 200, 255] # blue sprite | |
| bg = detect_background(rgba) | |
| assert bg.color[:3] == (255, 255, 255) | |
| assert bg.mask[9, 9] == False # noqa: E712 -- sprite interior untouched | |
| def test_colored_background_detected(): | |
| rgba = np.zeros((20, 20, 4), dtype=np.uint8) | |
| rgba[:, :, 3] = 255 | |
| rgba[:, :, :3] = [30, 200, 30] # green background | |
| rgba[5:15, 5:15] = [200, 30, 30, 255] # red sprite | |
| bg = detect_background(rgba) | |
| assert bg.color[:3] == (30, 200, 30) | |
| assert bg.mask[9, 9] == False # noqa: E712 | |
| def test_tolerance_absorbs_near_background_noise(): | |
| """ | |
| Slightly-off-black border pixels (e.g. from lossy JPEG compression | |
| artifacts) should still be classified as background within tolerance. | |
| """ | |
| rng = np.random.default_rng(0) | |
| rgba = np.zeros((20, 20, 4), dtype=np.uint8) | |
| rgba[:, :, 3] = 255 | |
| jitter = rng.integers(-5, 6, size=(20, 20, 3)) | |
| rgba[:, :, :3] = np.clip(0 + jitter, 0, 255).astype(np.uint8) | |
| rgba[5:15, 5:15] = [200, 50, 50, 255] | |
| bg = detect_background(rgba) | |
| # Most of the noisy near-black border should still register as background. | |
| assert bg.mask[0, 0] == True # noqa: E712 | |
| assert bg.mask.sum() > 200 # most of the 400px sheet minus the sprite | |
| def test_two_sprites_near_black_border_both_preserved(): | |
| """Two separate sprites each containing a black pixel of their own.""" | |
| rgba = np.zeros((30, 30, 4), dtype=np.uint8) | |
| rgba[:, :, 3] = 255 | |
| rgba[3:10, 3:10] = [80, 200, 90, 255] | |
| rgba[6, 6] = [0, 0, 0, 255] | |
| rgba[20:27, 20:27] = [90, 90, 220, 255] | |
| rgba[23, 23] = [0, 0, 0, 255] | |
| bg = detect_background(rgba) | |
| assert bg.mask[6, 6] == False # noqa: E712 | |
| assert bg.mask[23, 23] == False # noqa: E712 | |
| if __name__ == "__main__": | |
| import traceback | |
| tests = [(name, fn) for name, fn in list(globals().items()) if name.startswith("test_") and callable(fn)] | |
| passed, failed = 0, 0 | |
| for name, fn in tests: | |
| try: | |
| fn() | |
| print(f"PASS {name}") | |
| passed += 1 | |
| except Exception: | |
| print(f"FAIL {name}") | |
| traceback.print_exc() | |
| failed += 1 | |
| print(f"\n{passed} passed, {failed} failed") | |
| sys.exit(1 if failed else 0) | |