REF: merge NonConsolidateableMixin into ExtensionArray

pandas/core/internals/blocks.py

@@ -1598,12 +1598,22 @@ def _replace_coerce(
         return self
 
 
-class NonConsolidatableMixIn:
-    """ hold methods for the nonconsolidatable blocks """
+class ExtensionBlock(Block):
+    """
+    Block for holding extension types.
+
+    Notes
+    -----
+    This holds all 3rd-party extension array types. It's also the immediate
+    parent class for our internal extension types' blocks, CategoricalBlock.
+
+    ExtensionArrays are limited to 1-D.
+    """
 
     _can_consolidate = False
     _verify_integrity = False
     _validate_ndim = False
+    is_extension = True
 
     def __init__(self, values, placement, ndim=None):
         """
@@ -1614,6 +1624,8 @@ def __init__(self, values, placement, ndim=None):
         This will call continue to call __init__ for the other base
         classes mixed in with this Mixin.
         """
+        values = self._maybe_coerce_values(values)
+
         # Placement must be converted to BlockPlacement so that we can check
         # its length
         if not isinstance(placement, libinternals.BlockPlacement):
@@ -1627,6 +1639,10 @@ def __init__(self, values, placement, ndim=None):
                 ndim = 2
         super().__init__(values, placement, ndim=ndim)
 
+        if self.ndim == 2 and len(self.mgr_locs) != 1:
+            # TODO(2DEA): check unnecessary with 2D EAs
+            raise AssertionError("block.size != values.size")
+
     @property
     def shape(self):
         if self.ndim == 1:
@@ -1722,29 +1738,6 @@ def _get_unstack_items(self, unstacker, new_columns):
         mask = mask.any(0)
         return new_placement, new_values, mask
 
-
-class ExtensionBlock(NonConsolidatableMixIn, Block):
-    """
-    Block for holding extension types.
-
-    Notes
-    -----
-    This holds all 3rd-party extension array types. It's also the immediate
-    parent class for our internal extension types' blocks, CategoricalBlock.
-
-    ExtensionArrays are limited to 1-D.
-    """
-
-    is_extension = True
-
-    def __init__(self, values, placement, ndim=None):
-        values = self._maybe_coerce_values(values)
-        super().__init__(values, placement, ndim)
-
-        if self.ndim == 2 and len(self.mgr_locs) != 1:
-            # TODO(2DEA): check unnecessary with 2D EAs
-            raise AssertionError("block.size != values.size")
-
     def _maybe_coerce_values(self, values):
         """
         Unbox to an extension array.

pandas/tests/extension/test_external_block.py

@@ -3,12 +3,13 @@
 
 import pandas as pd
 from pandas.core.internals import BlockManager, SingleBlockManager
-from pandas.core.internals.blocks import Block, NonConsolidatableMixIn
+from pandas.core.internals.blocks import ExtensionBlock
 
 
-class CustomBlock(NonConsolidatableMixIn, Block):
+class CustomBlock(ExtensionBlock):
 
     _holder = np.ndarray
+    _can_hold_na = False
 
     def concat_same_type(self, to_concat, placement=None):
         """