added tests for _stack_bands and deprecated stack_raster_tifs. (#241)

* added tests for _stack_bands and deprecated stack_raster_tifs. Also edited _stack_bands in spatial.py since it needed to change ValueError to Exception for except clause to be accessed. Otherwise, the specific error in the test is an AttributeError.
* cleaned up imports and changed Exception to AssertionError in spatial.py stack function
* Adding warning message to stack_raster_tifs deprecation test

earthpy/spatial.py

@@ -254,8 +254,8 @@ def _stack_bands(sources, write_raster=False, dest=None):
         for src in sources:
             src.profile
 
-    except ValueError as ve:
-        raise ValueError("The sources object should be Dataset Reader")
+    except AttributeError as ae:
+        raise AttributeError("The sources object should be Dataset Reader")
         sys.exit()
 
     else:

earthpy/tests/test__stack_bands.py

@@ -0,0 +1,25 @@
+""" Tests for the _stack_bands() method """
+
+import numpy as np
+import pytest
+import earthpy.spatial as es
+
+
+@pytest.fixture
+def b1_b2_arrs():
+    b1 = np.array([[6, 7, 8, 9, 10], [16, 17, 18, 19, 20]])
+    b2 = np.array([[1, 2, 3, 4, 5], [14, 12, 13, 14, 17]])
+    return b1, b2
+
+
+def test__stack_bands(b1_b2_arrs):
+    """_stack_bands input should be of type DatasetReader."""
+
+    # Test data
+    b1, b2 = b1_b2_arrs
+
+    # Check ValueError for Dataset Reader
+    with pytest.raises(
+        AttributeError, match="The sources object should be Dataset Reader"
+    ):
+        es._stack_bands([b1, b2])

earthpy/tests/test_stack_raster_tifs.py

@@ -0,0 +1,23 @@
+""" Tests for the _stack_bands() method """
+
+import numpy as np
+import pytest
+import earthpy.spatial as es
+
+
+@pytest.fixture
+def b1_b2_arrs():
+    b1 = np.array([[6, 7, 8, 9, 10], [16, 17, 18, 19, 20]])
+    b2 = np.array([[1, 2, 3, 4, 5], [14, 12, 13, 14, 17]])
+    return b1, b2
+
+
+def test_stack_raster_tifs(b1_b2_arrs):
+    """stack_raster_tifs() should return a Warning."""
+
+    # Test data
+    b1, b2 = b1_b2_arrs
+
+    # Check Warning for Deprecation
+    with pytest.raises(Warning, match="stack_raster_tifs is deprecated"):
+        es.stack_raster_tifs([b1, b2], out_path="test.tif")