TEST: Test write modes

Author: effigies

nibabel/gifti/tests/test_gifti.py

@@ -128,6 +128,44 @@ def assign_metadata(val):
     pytest.raises(TypeError, assign_metadata, 'not-a-meta')
 
 
+@pytest.mark.parametrize('label', data_type_codes.value_set('label'))
+def test_image_typing(label):
+    dtype = data_type_codes.dtype[label]
+    if dtype == np.void:
+        return
+    arr = 127 * rng.random(
+        20,
+    )
+    try:
+        cast = arr.astype(label)
+    except TypeError:
+        return
+    darr = GiftiDataArray(cast, datatype=label)
+    img = GiftiImage(darrays=[darr])
+
+    # Force-write always works
+    force_rt = img.from_bytes(img.to_bytes(mode='force'))
+    assert np.array_equal(cast, force_rt.darrays[0].data)
+
+    # Compatibility mode does its best
+    if np.issubdtype(dtype, np.integer) or np.issubdtype(dtype, np.floating):
+        compat_rt = img.from_bytes(img.to_bytes(mode='compat'))
+        compat_darr = compat_rt.darrays[0].data
+        assert np.allclose(cast, compat_darr)
+        assert compat_darr.dtype in ('uint8', 'int32', 'float32')
+    else:
+        with pytest.raises(ValueError):
+            img.to_bytes(mode='compat')
+
+    # Strict mode either works or fails
+    if label in ('uint8', 'int32', 'float32'):
+        strict_rt = img.from_bytes(img.to_bytes(mode='strict'))
+        assert np.array_equal(cast, strict_rt.darrays[0].data)
+    else:
+        with pytest.raises(ValueError):
+            img.to_bytes(mode='strict')
+
+
 def test_dataarray_empty():
     # Test default initialization of DataArray
     null_da = GiftiDataArray()