Enhance test of scalar expressions

[leiysky]

So far, we only have integration test(e.g. fullstack-test, mock-test, sqllogic with randgen cases) and poor unit test to ensure correctness of scalar expressions, which has low test coverage and cannot help us find bugs automatically.

IMO, test of TiFlash scalar expressions should cover:

• for all the input argument, should tests 3 types of input column: column_vector, column_constant, column_null
• for all the input argument, the value of intput should include min_value, max_value, empty_value and other corner cases.

Tracking lists of tests:

• Add unit test for Math function add + #3495
• Math subtract -
• Math multuply *
• Math divide /
• Add unit test for Math function floor #3496
• Add unit test for Math function ceil #3497
• Add unit test for Math function abs #3498
• Add unit test for Math function mod #3525
• Add unit test for Math function sqrt #3499
• Add unit test for Math function log #3500
• Add unit test for Math function log2 #3501
• Add unit test for Math function log10 #3502
• Add unit test for Math function ln #3503
• Add unit test for Math function exp #3504
• Add unit test for Math function pow #3505
• Add unit test for Math function sign #3506
• Add unit test for Math function radians #3507
• Add unit test for Math function degrees #3508
• Add unit test for Math function conv #3509
• Add unit test for Math function crc32 #3510
• Add unit test for Math function round #3526
• Add unit test for String function like #3511
• Add unit test for String function substring #3527
• Add unit test for String function ascii #3512
• Add unit test for String function length #3513
• Add unit test for String function trim #3531
• Add unit test for String function position #3528
• Add unit test for String function format #3529
• Add unit test for String function ltrim #3532
• Add unit tests for String function rtrim #3533
• Add unit test for String function left #3515
• Add unit test for String function right #3516
• Addd unit test for String function char_length #3514
• Add unit test for String function substring_index #3530
• String function extract
• Add unit test for String function upper #3534
• Add unit test for String function lower #3535
• Add unit test for String function concat #3518
• Add unit test for String function concat_ws #3517
• String function replace
• Add unit test for String function strcmp #3769
• Time date_format
• Add unit test for Time function from_unixtime #3602
• Add unit test for Time function date #3522
• Add unit test for Time function year #3519
• Add unit test for Time function month #3520
• Add unit test for Time function day #3521
• Add unit test for Time function datediff #3523
• Add unit test for Time function timestampdiff #3524
• Time function hour
• Time function minute
• Time function second
• Time function micro_second
• Time function date_add/add_date
• Time function date_sub/sub_date
• Add unit test for Time function unix_timestamp #3603
• Add unittests for Time function str_to_date #3557
• Time function sysdate
• Comparison LT <
• Comparison GT >
• Comparison EQ =
• Comparison LE <=
• Comparison GE >=
• Comparison NE !=
• Logical and
• Logical or
• Logical not
• Add unit test for Conditional function ifnull #3604
• Add unit test for Conditional function if #3605
• Add unit test for Conditional function case when #3606
• Add unit test for Conditional function coalesce #3607
• CastIntAsXXX Add unittests for CastIntAsXXX #3437
• Add unittests for CastRealAsXXX #3554
• CastDecimalAsXXX
• CastStringAsXXX
• CastTimeAsXXX
• Add unit test for Bit operator bitand #3608
• Add unit test for Bit operator bitor #3609
• Add unit test for Bit operator bitnot #3610
• Add unit test for Bit operator bitxor #3611
• Other function in
• Other function isnull
• Other function json_length
• Other function inet_ntoa
• Other function inet_aton
• Other function inet6_ntoa
• Other function inet6_aton

[JaySon-Huang]

There is a known out-of-bound bug in json_length: #2705. /cc @windtalker