slt test coverage for CASE exprs with constant value lookup tables

datafusion/sqllogictest/test_files/case.slt

@@ -703,3 +703,137 @@ logical_plan
 physical_plan
 01)ProjectionExec: expr=[column1@0 as CASE WHEN CASE WHEN t.a IS NOT NULL THEN t.a ELSE Int64(1) END IS NOT NULL THEN t.a ELSE Int64(1) END]
 02)--DataSourceExec: partitions=1, partition_sizes=[1]
+
+#####
+# CASE with literal characters (to test lookup table CASE optimization)
+#####
+statement ok
+create table source (letter varchar) as values ('a'), ('b'), (NULL), ('c'), ('a'), ('c'), ('d');
+
+# Table with different string types
+statement ok
+create table letters as
+select
+  arrow_cast(letter, 'Utf8') as letter_utf8,
+  arrow_cast(letter, 'LargeUtf8') as letter_large_utf8,
+  arrow_cast(letter, 'Utf8View') as letter_utf8_view,
+  arrow_cast(letter, 'Dictionary(Int32, Utf8)') as letter_string_dict,
+from source;
+
+
+query TIIIII
+select
+  letter_utf8 as letter
+  ,CASE letter_utf8       WHEN 'b' THEN 1 WHEN 'a' THEN 2 WHEN 'd' THEN 3 ELSE 0 END as utf8
+  ,CASE letter_large_utf8 WHEN 'b' THEN 1 WHEN 'a' THEN 2 WHEN 'd' THEN 3 ELSE 0 END as large_utf8
+  ,CASE letter_utf8_view  WHEN 'b' THEN 1 WHEN 'a' THEN 2 WHEN 'd' THEN 3 ELSE 0 END as utf8_view
+  ,CASE letter_string_dict WHEN 'b' THEN 1 WHEN 'a' THEN 2 WHEN 'd' THEN 3 ELSE 0 END as string_dict
+  ,CASE letter_utf8       WHEN 'b' THEN 1 WHEN NULL THEN 2 WHEN 'd' THEN 3 ELSE 0 END as utf8_with_null
+FROM letters;
+----
+a 2 2 2 2 0
+b 1 1 1 1 1
+NULL 0 0 0 0 0
+c 0 0 0 0 0
+a 2 2 2 2 0
+c 0 0 0 0 0
+d 3 3 3 3 3
+
+statement ok
+create table letters_binary as
+select
+  arrow_cast(letter, 'Binary') as letter_binary,
+  arrow_cast(letter, 'LargeBinary') as letter_large_binary,
+  arrow_cast(letter, 'BinaryView') as letter_binary_view,
+  arrow_cast(letter, 'Dictionary(Int32, Binary)') as letter_binary_dict,
+  arrow_cast(arrow_cast(letter, 'Binary'), 'FixedSizeBinary(1)') as letter_fsb
+from source;
+
+query ?IIIII
+select
+    letter_binary as letter
+    ,CASE letter_binary       WHEN X'62' THEN 1 WHEN X'61' THEN 2 WHEN X'64' THEN 3 ELSE 0 END as binary
+    ,CASE letter_large_binary WHEN X'62' THEN 1 WHEN X'61' THEN 2 WHEN X'64' THEN 3 ELSE 0 END as large_binary
+    ,CASE letter_binary_view  WHEN X'62' THEN 1 WHEN X'61' THEN 2 WHEN X'64' THEN 3 ELSE 0 END as binary_view
+    ,CASE letter_binary_dict  WHEN X'62' THEN 1 WHEN X'61' THEN 2 WHEN X'64' THEN 3 ELSE 0 END as binary_dict
+    ,CASE letter_fsb          WHEN X'62' THEN 1 WHEN X'61' THEN 2 WHEN X'64' THEN 3 ELSE 0 END as fsb
+FROM letters_binary;
+----
+61 2 2 2 2 2
+62 1 1 1 1 1
+NULL 0 0 0 0 0
+63 0 0 0 0 0
+61 2 2 2 2 2
+63 0 0 0 0 0
+64 3 3 3 3 3
+
+statement ok
+drop table source;
+
+
+statement ok
+drop table letters;
+
+statement ok
+drop table letters_binary;
+
+# Tests for CASE with boolean expressions
+statement ok
+create table booleans (b boolean) as values (true), (false), (null), (true), (null), (false);
+
+query BIII
+select
+    b as boolean_value
+    ,CASE b WHEN true THEN 1 WHEN false THEN 2 ELSE 0 END as boolean_case
+    ,CASE b WHEN false THEN 1 WHEN true THEN 2 ELSE 0 END as boolean_case_rev
+    ,CASE b WHEN true THEN 1 WHEN NULL THEN 2 WHEN false THEN 3 ELSE 0 END as boolean_with_nulls
+FROM booleans;
+----
+true 1 2 1
+false 2 1 3
+NULL 0 0 0
+true 1 2 1
+NULL 0 0 0
+false 2 1 3
+
+statement ok
+drop table booleans;
+
+# Tests for CASE with floating point literals
+statement ok
+create table float_source (f float) as values (1.0), (2.0), (null), (3.5), (2.0), (null);
+
+statement ok
+create table floats as
+select
+    arrow_cast(f, 'Float16') as f16,
+    arrow_cast(f, 'Float32') as f32,
+    arrow_cast(f, 'Float64') as f64,
+    arrow_cast(f, 'Dictionary(Int32, Float32)') as f32_dict,
+from float_source;
+
+query RTTTT
+select
+    f32 as float_value
+    ,CASE f16      WHEN 1.0 THEN 'one'  WHEN 3.5 THEN 'three_point_five' WHEN 2.0 THEN 'two' ELSE 'N/A' END as f16_case
+    ,CASE f32      WHEN 1.0 THEN 'one'  WHEN 3.5 THEN 'three_point_five' WHEN 2.0 THEN 'two' ELSE 'N/A' END as f32_case
+    ,CASE f64      WHEN 1.0 THEN 'one'  WHEN 3.5 THEN 'three_point_five' WHEN 2.0 THEN 'two' ELSE 'N/A' END as f64_case
+    ,CASE f32_dict WHEN 1.0 THEN 'one'  WHEN 3.5 THEN 'three_point_five' WHEN 2.0 THEN 'two' ELSE 'N/A' END as f32_dict_case
+FROM floats;
+----
+1 one one one one
+2 two two two two
+NULL N/A N/A N/A N/A
+3.5 three_point_five three_point_five three_point_five three_point_five
+2 two two two two
+NULL N/A N/A N/A N/A
+
+statement ok
+drop table float_source;
+
+statement ok
+drop table floats;
+
+#####
+# End of lookup table CASE tests
+#####