test/prefixes.test

# 2018-01-15
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is prefixes.c extension
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix unionvtab

ifcapable !vtab {
  finish_test
  return
}

load_static_extension db prefixes

foreach {tn zLeft zRight expected} {
  1 abcdxxx abcyy    3
  2 abcdxxx bcyyy    0
  3 abcdxxx ab       2
  4 ab      abcd     2

  5 "xyz\u1234xz" "xyz\u1234xy" 5
  6 "xyz\u1234"   "xyz\u1234xy" 4
  7 "xyz\u1234"   "xyz\u1234"   4
  8 "xyz\u1234xy" "xyz\u1234"   4
  9 "xyz\u1234xy" "xyz\u1233"   3
 10 "xyz\u1234xy" "xyz\u1235"   3
} {
  do_execsql_test 1.$tn { SELECT prefix_length($zLeft, $zRight) } $expected
}


do_execsql_test 2.0 {
  CREATE TABLE t1(k TEXT UNIQUE, v INTEGER);
  INSERT INTO t1 VALUES
    ('aback', 1),
    ('abaft', 2),
    ('abandon', 3),
    ('abandoned', 4),
    ('abandoning', 5),
    ('abandonment', 6),
    ('abandons', 7),
    ('abase', 8),
    ('abased', 9),
    ('abasement', 10),
    ('abasements', 11),
    ('abases', 12),
    ('abash', 13),
    ('abashed', 14),
    ('abashes', 15),
    ('abashing', 16),
    ('abasing', 17),
    ('abate', 18),
    ('abated', 19),
    ('abatement', 20),
    ('abatements', 21);
}

foreach {tn INPUT expected} {
  1 abatementt   abatement
  2 abashet      abash
  3 abandonio    abandon
  4 abasemenu    abase
} {
  do_execsql_test 2.$tn {
    WITH finder(str) AS (
      SELECT (SELECT max(k) FROM t1 WHERE k<=$INPUT)
        UNION ALL
        SELECT (
          SELECT max(k) FROM t1 
          WHERE k<=substr($INPUT, 1, prefix_length(finder.str, $INPUT))
        ) FROM finder WHERE length(finder.str)>0
      )
    SELECT str FROM finder WHERE length(str)==prefix_length(str, $INPUT) LIMIT 1
  } $expected
}

finish_test