Fixups:

* Ensure data generated OK.
* Remove erroneous comments about alignment. That was user error.

Author: TomAugspurger

pandas/core/arrays/interval.py

@@ -779,8 +779,7 @@ def take(self, indices, allow_fill=False, fill_value=None, axis=None,
 
     def where(self, cond, other):
         if is_scalar(other) and isna(other):
-            lother = other
-            rother = other
+            lother = rother = other
         else:
             self._check_closed_matches(other, name='other')
             lother = other.left

pandas/tests/extension/base/methods.py

@@ -210,8 +210,7 @@ def test_where_series(self, data, na_value, as_frame):
 
         if as_frame:
             ser = ser.to_frame(name='a')
-            # TODO: alignment is broken for ndarray `cond`
-            cond = pd.DataFrame({"a": cond})
+            cond = cond.reshape(-1, 1)
 
         result = ser.where(cond)
         expected = pd.Series(cls._from_sequence([a, a, na_value, na_value],
@@ -225,9 +224,7 @@ def test_where_series(self, data, na_value, as_frame):
         cond = np.array([True, False, True, True])
         other = cls._from_sequence([a, b, a, b], dtype=data.dtype)
         if as_frame:
-            # TODO: alignment is broken for ndarray `cond`
             other = pd.DataFrame({"a": other})
-            # TODO: alignment is broken for array `other`
             cond = pd.DataFrame({"a": cond})
         result = ser.where(cond, other)
         expected = pd.Series(cls._from_sequence([a, b, b, b],

pandas/tests/extension/conftest.py

@@ -11,7 +11,11 @@ def dtype():
 
 @pytest.fixture
 def data():
-    """Length-100 array for this type."""
+    """Length-100 array for this type.
+
+    * data[0] and data[1] should both be non missing
+    * data[0] and data[1] should not gbe equal
+    """
     raise NotImplementedError
 
 

pandas/tests/extension/test_categorical.py

@@ -25,7 +25,12 @@
 
 
 def make_data():
-    return np.random.choice(list(string.ascii_letters), size=100)
+    while True:
+        values = np.random.choice(list(string.ascii_letters), size=100)
+        # ensure we meet the requirement
+        if values[0] != values[1]:
+            break
+    return values
 
 
 @pytest.fixture

pandas/tests/extension/test_sparse.py

@@ -13,6 +13,8 @@ def make_data(fill_value):
         data = np.random.uniform(size=100)
     else:
         data = np.random.randint(1, 100, size=100)
+        if data[0] == data[1]:
+            data[0] += 1
 
     data[2::3] = fill_value
     return data