Add tests to make sure transparent files are well handled (#167)

* Add new transparent test image

autocrop/autocrop.py

@@ -47,10 +47,13 @@ def distance(pt1, pt2):
 
 def bgr_to_rbg(img):
     """Given a BGR (cv2) numpy array, returns a RBG (standard) array."""
-    dimensions = len(img.shape)
-    if dimensions == 2:
+    # Don't do anything for grayscale images
+    if img.ndim == 2:
         return img
-    return img[..., ::-1]
+
+    # Flip the channels. Use explicit indexing in case RGBA is used.
+    img[:, :, [0, 1, 2]] = img[:, :, [2, 1, 0]]
+    return img
 
 
 def gamma(img, correction):

tests/test_autocrop.py

@@ -2,6 +2,7 @@
 
 from glob import glob
 import shutil
+
 import pytest  # noqa: F401
 import cv2
 import numpy as np
@@ -79,16 +80,16 @@ def test_adjust_boundaries(values, expected_result):
 @pytest.mark.slow
 @pytest.mark.parametrize(
     "height, width",
-    [(500, 500), (900, 500), (500, 900), (1000, 1200)],
+    [(500, 500), (700, 500), (500, 700), (1000, 1200)],
 )
 def test_detect_face_in_cropped_image(height, width, integration):
-    """An image cropped by Cropper should have a face detectable.
+    """
+    An image cropped by Cropper should have a face detectable.
     This defends us against image warping or crops outside the region
     of interest.
     """
-    c = Cropper(height=height, width=width)
+    c = Cropper(height=height, width=width, face_percent=1, resize=False)
     faces = [f for f in glob("tests/test/*") if not f.endswith("md")]
-    print(faces)
     for face in faces:
         try:
             img_array = c.crop(face)
@@ -119,3 +120,14 @@ def test_face_percent(face_percent):
         with pytest.raises(ValueError) as e:
             Cropper(face_percent=face_percent)
             assert "argument must be between 0 and 1" in str(e)
+
+
+def test_transparent_png(integration):
+    c = Cropper()
+    img = c.crop("tests/test/expo_67.png")
+
+    # Make sure we're still RGBA
+    assert img.shape[-1] == 4
+
+    # Make sure the first pixel is transparent
+    assert img[0, 0, 3] == 0

tests/test_cli.py

@@ -12,6 +12,8 @@
 from autocrop.autocrop import Cropper
 from autocrop.cli import command_line_interface, main, size, confirmation, chk_extension
 
+NUM_FILES = 12
+
 
 @pytest.fixture()
 def integration():
@@ -160,7 +162,7 @@ def test_main_overwrites_when_same_input_and_output(integration):
     sys.argv = ["", "--no-confirm", "-i", "tests/test", "-o", "tests/test"]
     command_line_interface()
     output_files = os.listdir(sys.argv[-1])
-    assert len(output_files) == 11
+    assert len(output_files) == NUM_FILES
 
 
 # @mock.patch("autocrop.autocrop.Cropper", side_)
@@ -176,7 +178,7 @@ def crop(self, *args):
     m = MonkeyCrop()
     monkeypatch.setattr(Cropper, "crop", m.crop)
     main("tests/test", None, None, None)
-    assert m.count == 10
+    assert m.count == NUM_FILES - 1
 
 
 @mock.patch("autocrop.cli.main", lambda *args: None)
@@ -212,7 +214,7 @@ def test_noface_files_copied_over_if_output_d_specified(integration):
     sys.argv = ["", "-i", "tests/test", "-o", "tests/crop"]
     command_line_interface()
     output_files = os.listdir(sys.argv[-1])
-    assert len(output_files) == 10
+    assert len(output_files) == NUM_FILES - 1
 
 
 @pytest.mark.slow
@@ -229,7 +231,7 @@ def test_nofaces_copied_to_reject_d_if_both_reject_and_output_d(integration):
     command_line_interface()
     output_files = os.listdir(sys.argv[-3])
     reject_files = os.listdir(sys.argv[-1])
-    assert len(output_files) == 7
+    assert len(output_files) == NUM_FILES - 4
     assert len(reject_files) == 3
 
 
@@ -240,7 +242,7 @@ def test_image_files_overwritten_if_no_output_dir(integration):
     command_line_interface()
     # We have the same number of files
     output_files = os.listdir(sys.argv[-1])
-    assert len(output_files) == 11
+    assert len(output_files) == NUM_FILES
     # Images with a face have been cropped
     shape = cv2.imread("tests/test/king.jpg").shape
     assert shape == (500, 500, 3)