should be it

external/duckdb/test/sql/function/string/test_left.test

@@ -0,0 +1,107 @@
+# name: test/sql/function/string/test_left.test
+# description: LEFT test
+# group: [string]
+
+statement ok
+PRAGMA enable_verification
+
+foreach FUN LEFT LEFT_GRAPHEME
+
+# test LEFT on positive positions
+query TTTTT
+SELECT ${FUN}('abcd', 0), ${FUN}('abc', 1), ${FUN}('abc', 2), ${FUN}('abc', 3), ${FUN}('abc', 4)
+----
+(empty)	a	ab	abc	abc
+
+query TTTTT
+SELECT ${FUN}('🦆ab', 0), ${FUN}('🦆ab', 1), ${FUN}('🦆ab', 2), ${FUN}('🦆ab', 3), ${FUN}('🦆ab', 4)
+----
+(empty)	🦆	🦆a	🦆ab	🦆ab
+
+# test LEFT on negative positions
+query TTTTT
+SELECT ${FUN}('abcd', 0), ${FUN}('abc', -1), ${FUN}('abc', -2), ${FUN}('abc', -3), ${FUN}('abc', -4)
+----
+(empty)	ab	a	(empty)	(empty)
+
+query TTTTT
+SELECT ${FUN}('🦆ab', 0), ${FUN}('🦆ab', -1), ${FUN}('🦆ab', -2), ${FUN}('🦆ab', -3), ${FUN}('🦆ab', -4)
+----
+(empty)	🦆a	🦆	(empty)	(empty)
+
+# test LEFT on NULL values
+query TTT
+SELECT ${FUN}(NULL, 0), ${FUN}('abc', NULL), ${FUN}(NULL, NULL)
+----
+NULL	NULL	NULL
+
+query TTT
+SELECT ${FUN}(NULL, 0), ${FUN}('🦆ab', NULL), ${FUN}(NULL, NULL)
+----
+NULL	NULL	NULL
+
+# test on tables
+statement ok
+DROP TABLE IF EXISTS strings
+
+statement ok
+CREATE TABLE strings(a STRING, b BIGINT)
+
+statement ok
+INSERT INTO STRINGS VALUES ('abcd', 0), ('abc', 1), ('abc', 2), ('abc', 3), ('abc', 4)
+
+query T
+SELECT ${FUN}(a, b) FROM strings
+----
+(empty)
+a
+ab
+abc
+abc
+
+statement ok
+DROP TABLE IF EXISTS strings
+
+statement ok
+CREATE TABLE strings(a STRING, b BIGINT)
+
+statement ok
+INSERT INTO STRINGS VALUES ('abcd', 0), ('abc', -1), ('abc', -2), ('abc', -3), ('abc', -4)
+
+query T
+SELECT ${FUN}(a, b) FROM strings
+----
+(empty)
+ab
+a
+(empty)
+(empty)
+
+statement ok
+DROP TABLE IF EXISTS strings
+
+statement ok
+CREATE TABLE strings(a STRING, b BIGINT)
+
+statement ok
+INSERT INTO STRINGS VALUES (NULL, 0), ('abc', NULL), (NULL, NULL)
+
+query T
+SELECT ${FUN}(a, b) FROM strings
+----
+NULL
+NULL
+NULL
+
+endloop
+
+# grapheme clusters
+query TTTT
+SELECT LEFT_GRAPHEME('🦆🤦S̈', 0), LEFT_GRAPHEME('🦆🤦S̈', 1), LEFT_GRAPHEME('🦆🤦S̈', 2), LEFT_GRAPHEME('🦆🤦S̈', 3)
+----
+(empty)	🦆	🦆🤦	🦆🤦S̈
+
+query TTTT
+SELECT LEFT_GRAPHEME('🦆🤦S̈', 0), LEFT_GRAPHEME('🦆🤦S̈', -1), LEFT_GRAPHEME('🦆🤦S̈', -2), LEFT_GRAPHEME('🦆🤦S̈', -3)
+----
+(empty)	🦆🤦	🦆	(empty)