TEST: Update tests to match new behavior

Author: effigies

nibabel/nifti1.py

@@ -2299,11 +2299,22 @@ def _get_smallest_dtype(
     >>> _get_smallest_dtype(np.array([-65536, 65536]))
     dtype('int32')
     >>> _get_smallest_dtype(np.array([-2147483648, 2147483648]))
+
+    By default floating point types are not searched:
+
     >>> _get_smallest_dtype(np.array([1.]))
-    dtype('float32')
     >>> _get_smallest_dtype(np.array([2. ** 1000]))
     >>> _get_smallest_dtype(np.longdouble(2) ** 2000)
     >>> _get_smallest_dtype(np.array([1+0j]))
+
+    However, this function can be passed "legal" floating point types, and
+    the logic works the same.
+
+    >>> _get_smallest_dtype(np.array([1.]), ftypes=('float32',))
+    dtype('float32')
+    >>> _get_smallest_dtype(np.array([2. ** 1000]), ftypes=('float32',))
+    >>> _get_smallest_dtype(np.longdouble(2) ** 2000, ftypes=('float32',))
+    >>> _get_smallest_dtype(np.array([1+0j]), ftypes=('float32',))
     """
     arr = np.asanyarray(arr)
     if np.issubdtype(arr.dtype, np.floating):

nibabel/tests/test_nifti1.py

@@ -1121,11 +1121,20 @@ def test_write_scaling(self):
 
     def test_dynamic_dtype_aliases(self):
         for in_dt, mn, mx, alias, effective_dt in [
-                (np.int64, 0, 255, 'compat', np.uint8),
-                (np.int64, 0, 256, 'compat', np.int16),
-                (np.int64, -1, 255, 'compat', np.int16),
-                (np.int64, 0, 32768, 'compat', np.int32),
-                (np.int64, 0, 4294967296, 'compat', None),
+                (np.uint8, 0, 255, 'compat', np.uint8),
+                (np.int8, 0, 127, 'compat', np.uint8),
+                (np.int8, -128, 127, 'compat', np.int16),
+                (np.int16, -32768, 32767, 'compat', np.int16),
+                (np.uint16, 0, 32767, 'compat', np.int16),
+                (np.uint16, 0, 65535, 'compat', np.int32),
+                (np.int32, -2**31, 2**31-1, 'compat', np.int32),
+                (np.uint32, 0, 2**31-1, 'compat', np.int32),
+                (np.uint32, 0, 2**32-1, 'compat', None),
+                (np.int64, -2**31, 2**31-1, 'compat', np.int32),
+                (np.uint64, 0, 2**31-1, 'compat', np.int32),
+                (np.int64, 0, 2**32-1, 'compat', None),
+                (np.uint64, 0, 2**32-1, 'compat', None),
+                (np.float32, 0, 1e30, 'compat', np.float32),
                 (np.float64, 0, 1e30, 'compat', np.float32),
                 (np.float64, 0, 1e40, 'compat', None),
                 (np.int64, 0, 255, 'smallest', np.uint8),