fix test relative location

tests/test_autocrop.py

@@ -4,18 +4,21 @@
 
 import cv2
 import numpy as np
+import os.path
+
 from autocrop.autocrop import gamma, main, crop
 import pytest
 
-matrix = np.array([[1,2,3],[4,5,6],[7,8,9]])
-noise = cv2.imread('data/noise.png')
 
 def test_gamma_can_do_sqrt():
     """This function is so tightly coupled to cv2 it's probably useless.
     Still might flag cv2 or numpy boo-boos."""
+    matrix = np.array([[1,2,3],[4,5,6],[7,8,9]])
     expected = np.uint8([[15, 22, 27], [31, 35, 39], [42, 45, 47]])
     np.testing.assert_array_equal(gamma(img=matrix, correction=0.5), expected)
 
 def test_crop_noise_returns_none():
+    loc = 'tests/data/noise.png'
+    noise = cv2.imread(loc)
     assert crop(noise) == None