test cases for grayscale function, py file

tests/test_grayscale.py

@@ -1,9 +1,25 @@
 import unittest
 import numpy as np
-from imagenie import grayscale  
+from your_module import grayscale  # Replace 'your_module' with the actual module name
 
 def test_grayscale():
-    """Test all cases for the grayscale function."""
+    """
+    Test all cases for the grayscale function.
+
+    This function tests the following scenarios:
+
+    1. **Grayscale Image (2D Array):**
+       Ensures that an image already in grayscale (2D array) is returned unchanged.
+
+    2. **Empty Array:**
+       Validates that an empty image array is handled correctly and returned as-is.
+
+    3. **Invalid Input Type:**
+       Verifies that a `TypeError` is raised when the input is not a NumPy array (e.g., a Python list).
+
+    4. **Black-and-White Image (3D Array):**
+       Tests that an image represented as a 3D array with identical channel values is correctly converted to a 2D grayscale array.
+    """
 
     # Test that an already grayscale image (2D array) is returned unchanged
     gray_image = np.array([[10, 20, 30], [40, 50, 60]], dtype=np.uint8)
@@ -21,6 +37,13 @@ def test_grayscale():
     except TypeError as e:
         assert str(e) == "The input image must be a NumPy array."
 
+    # Test that an image already in black and white (3D array but with identical channels) is returned as 2D
+    bw_image = np.array([[[50, 50, 50], [100, 100, 100]],
+                         [[150, 150, 150], [200, 200, 200]]], dtype=np.uint8)
+    expected_bw_result = np.array([[50, 100], [150, 200]], dtype=np.uint8)
+    result = grayscale(bw_image)
+    np.testing.assert_array_equal(result, expected_bw_result)
+
 if __name__ == "__main__":
     test_grayscale()
-    print("All tests passed.")
+    print("All tests passed.")