fix(interactive-repr): ensure that null scalars can be repr'd interactively

ibis/backends/duckdb/tests/test_datatypes.py

@@ -1,11 +1,16 @@
 from __future__ import annotations
 
+import string
+
+import hypothesis as h
+import hypothesis.strategies as st
 import numpy as np
 import pytest
 from pytest import param
 
 import ibis
 import ibis.expr.datatypes as dt
+import ibis.tests.strategies as its
 from ibis.backends.sql.datatypes import DuckDBType
 
 
@@ -115,3 +120,57 @@
 
     sql = str(ibis.to_sql(expr, dialect="duckdb"))
     snapshot.assert_match(sql, "out.sql")
+
+
+def null_literal(array_min_size: int = 0, array_max_size: int | None = None):
+    true = st.just(True)
+
+    field_names = st.text(alphabet=string.ascii_lowercase + string.digits, min_size=1)
+    num_fields = st.integers(min_value=1, max_value=20)
+
+    recursive = st.deferred(
+        lambda: (
+            its.primitive_dtypes(nullable=true, include_null=False)
+            | its.string_dtype(nullable=true)
+            | its.binary_dtype(nullable=true)
+            | st.builds(dt.JSON, binary=st.just(False), nullable=true)
+            | its.macaddr_dtype(nullable=true)
+            | its.uuid_dtype(nullable=true)
+            | its.temporal_dtypes(nullable=true)
+            | its.array_dtypes(recursive, nullable=true, length=st.none())
+            | its.map_dtypes(recursive, recursive, nullable=true)
+            | its.struct_dtypes(
+                recursive, nullable=true, names=field_names, num_fields=num_fields
+            )
+        )
+    )
+
+    return st.builds(
+        ibis.null,
+        its.primitive_dtypes(nullable=true, include_null=False)
+        | its.string_dtype(nullable=true)
+        | its.binary_dtype(nullable=true)
+        | st.builds(dt.JSON, binary=st.just(False), nullable=true)
+        | its.macaddr_dtype(nullable=true)
+        | its.uuid_dtype(nullable=true)
+        | its.temporal_dtypes(nullable=true)
+        | its.array_dtypes(recursive, nullable=true, length=st.none())
+        | its.map_dtypes(recursive, recursive, nullable=true)
+        | its.struct_dtypes(
+            recursive, nullable=true, names=field_names, num_fields=num_fields
+        ),
+    )
+
+
+@h.given(lit=null_literal(array_min_size=1, array_max_size=8192))
+@h.settings(suppress_health_check=[h.HealthCheck.function_scoped_fixture])
+def test_null_scalar(con, lit, monkeypatch):
+    monkeypatch.setattr(ibis.options, "default_backend", con)
+    monkeypatch.setattr(ibis.options, "interactive", True)
+
+    result = repr(lit)
+    expected = """\
+┌──────┐
+│ NULL │
+└──────┘"""
+    assert result == expected

ibis/expr/types/generic.py

@@ -2895,7 +2895,7 @@ def null(type: dt.DataType | str | None = None, /) -> Value:
     AttributeError: 'NullScalar' object has no attribute 'upper'
     >>> ibis.null(str).upper()
     ┌──────┐
-    │ None │
+    │ NULL │
     └──────┘
     >>> ibis.null(str).upper().isnull()
     ┌──────┐

ibis/expr/types/pretty.py

@@ -294,14 +294,20 @@ def _to_rich_scalar(
     max_string: int | None = None,
     max_depth: int | None = None,
 ) -> Pretty:
-    value = format_values(
-        expr.type(),
-        [expr.to_pyarrow().as_py()],
-        max_length=max_length or ibis.options.repr.interactive.max_length,
-        max_string=max_string or ibis.options.repr.interactive.max_string,
-        max_depth=max_depth or ibis.options.repr.interactive.max_depth,
-    )[0]
-    return Panel(value, expand=False, box=box.SQUARE)
+    value = expr.to_pyarrow().as_py()
+
+    if value is None:
+        formatted_value = Text.styled("NULL", style="dim")
+    else:
+        (formatted_value,) = format_values(
+            expr.type(),
+            [value],
+            max_length=max_length or ibis.options.repr.interactive.max_length,
+            max_string=max_string or ibis.options.repr.interactive.max_string,
+            max_depth=max_depth or ibis.options.repr.interactive.max_depth,
+        )
+
+    return Panel(formatted_value, expand=False, box=box.SQUARE)
 
 
 def _to_rich_table(

ibis/tests/strategies.py

@@ -128,23 +128,25 @@ def interval_dtype(interval=_interval, nullable=_nullable):
     return st.builds(dt.Interval, unit=interval, nullable=nullable)
 
 
-def temporal_dtypes(timezone=_timezone, interval=_interval, nullable=_nullable):
+def temporal_dtypes(timezone=_timezone, nullable=_nullable):
     return st.one_of(
         date_dtype(nullable=nullable),
         time_dtype(nullable=nullable),
         timestamp_dtype(timezone=timezone, nullable=nullable),
     )
 
 
-def primitive_dtypes(nullable=_nullable):
-    return st.one_of(
-        null_dtype,
-        boolean_dtype(nullable=nullable),
-        integer_dtypes(nullable=nullable),
-        floating_dtypes(nullable=nullable),
-        date_dtype(nullable=nullable),
-        time_dtype(nullable=nullable),
+def primitive_dtypes(nullable=_nullable, include_null=True):
+    primitive = (
+        boolean_dtype(nullable=nullable)
+        | integer_dtypes(nullable=nullable)
+        | floating_dtypes(nullable=nullable)
+        | date_dtype(nullable=nullable)
+        | time_dtype(nullable=nullable)
     )
+    if include_null:
+        primitive |= null_dtype
+    return primitive
 
 
 _item_strategy = primitive_dtypes()
@@ -174,7 +176,7 @@ def struct_dtypes(
     nullable=_nullable,
 ):
     num_fields = draw(num_fields)
-    names = draw(st.lists(names, min_size=num_fields, max_size=num_fields))
+    names = draw(st.lists(names, min_size=num_fields, max_size=num_fields, unique=True))
     types = draw(st.lists(types, min_size=num_fields, max_size=num_fields))
     fields = dict(zip(names, types))
     return dt.Struct(fields, nullable=draw(nullable))