# name: test/sql/function/string/test_concat.test
# description: Test concat function
# group: [string]

statement ok
SET default_null_order='nulls_first';

# Test Case disclaimer

# Assertions built using the Domain Testing technique
# at: https://bbst.courses/wp-content/uploads/2018/01/Kaner-Intro-to-Domain-Testing-2018.pdf


statement ok
PRAGMA enable_verification

statement ok
CREATE TABLE strings(s VARCHAR)

statement ok
INSERT INTO strings VALUES ('hello'), ('world'), (NULL)

# normal concat
query T
SELECT s || ' ' || s FROM strings ORDER BY s
----
NULL
hello hello
world world

# unicode concat
query T
SELECT s || ' ' || '🦆' FROM strings ORDER BY s
----
NULL
hello 🦆
world 🦆

query T
SELECT s || ' ' || '🦆' FROM strings ORDER BY s
----
NULL
hello 🦆
world 🦆

# concat with constant NULL
query T
SELECT s || ' ' || '🦆' || NULL FROM strings ORDER BY s
----
NULL
NULL
NULL

# concat requires at least one argument
statement error
SELECT CONCAT()
----

# concat with one argument works
query T
SELECT CONCAT('hello')
----
hello

# varargs concat
query T
SELECT CONCAT('hello', 33, 22)
----
hello3322

# CONCAT ignores null values
query T
SELECT CONCAT('hello', 33, NULL, 22, NULL)
----
hello3322

# this also applies to non-constant null values
query T
SELECT CONCAT('hello', ' ', s) FROM strings ORDER BY s
----
hello 
hello hello
hello world