test: Forge::modifyColumn() and null

[kenjis]

Needs #7301

Description
From https://zenn.dev/naente/articles/50935eb55c14ea (CodeIgniter4 PostgreSQL always adds NOT NULL constraints when running modifyColumn())

See the current behavior: #7302 (comment)

• add test for Forge::modifyColumn() and null

This bug was fixed in v4.3.4:

• fix: [SQLite3][Postgres][SQLSRV][OCI8] Forge::modifyColumn() changes NULL constraint incorrectly #7371

Related #7235

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[kenjis]

@codeigniter4/database-team
It seems Postgre, SQLSRV, SQLite3 add NOT NULL constraints when running modifyColumn().
See the test: https://github.com/codeigniter4/CodeIgniter4/pull/7302/files#diff-489cc58f8341d1fa6ca26b7bb857562d4274924d2dc691ca64e9dc609731b8eaR1285
Are these bugs or not?

[sclubricants]

Looks like nullable is the default. What is the matter with this?

[kenjis]

I did not look into all drivers, but Postgre changes to NOT NULL in all cases.
There is no way to keep nuallble. So it is clearly a bug.

Another issue is these behaviors are not consistent. As you see all tests pass
on MySQLi and OCI8.

If a dev changes DB driver, e.g. MySQLi to Postgres,
the definitiion of the table will change when running migrations.

[kenjis]

        $this->forge->addField([
            'col1' => ['type' => 'VARCHAR', 'constraint' => 255, 'null' => true],
            'col2' => ['type' => 'VARCHAR', 'constraint' => 255, 'null' => true],
            'col3' => ['type' => 'VARCHAR', 'constraint' => 255, 'null' => true],
        ]);
        $this->forge->createTable('forge_test_modify');

        $this->forge->modifyColumn('forge_test_modify', [
            'col1' => ['type' => 'VARCHAR', 'constraint' => 1],
            'col2' => ['type' => 'VARCHAR', 'constraint' => 1, 'null' => true],
            'col3' => ['type' => 'VARCHAR', 'constraint' => 1, 'null' => false],
        ]);

        $this->db->resetDataCache();

        $fields = $this->db->getFieldData('forge_test_modify');
        dd($fields);

Postgres:

array (3) [
    0 => stdClass#249 (5) (
        public 'name' -> string (4) "col1"
        public 'type' -> string (17) "character varying"
        public 'nullable' -> boolean false  // MySQLi true
        public 'default' -> null
        public 'max_length' -> string (1) "1"
    )
    1 => stdClass#74 (5) (
        public 'name' -> string (4) "col2"
        public 'type' -> string (17) "character varying"
        public 'nullable' -> boolean false  // should be true
        public 'default' -> null
        public 'max_length' -> string (1) "1"
    )
    2 => stdClass#75 (5) (
        public 'name' -> string (4) "col3"
        public 'type' -> string (17) "character varying"
        public 'nullable' -> boolean false
        public 'default' -> null
        public 'max_length' -> string (1) "1"
    )
]

SQLSRV:

array (3) [
    0 => stdClass#249 (5) (
        public 'name' -> string (4) "col1"
        public 'type' -> string (7) "varchar"
        public 'default' -> null
        public 'max_length' -> integer 1
        public 'nullable' -> boolean false  // MySQLi true
    )
    1 => stdClass#74 (5) (
        public 'name' -> string (4) "col2"
        public 'type' -> string (7) "varchar"
        public 'default' -> null
        public 'max_length' -> integer 1
        public 'nullable' -> boolean false  // should be true
    )
    2 => stdClass#75 (5) (
        public 'name' -> string (4) "col3"
        public 'type' -> string (7) "varchar"
        public 'default' -> null
        public 'max_length' -> integer 1
        public 'nullable' -> boolean false
    )
]

SQLite3:

array (3) [
    0 => stdClass#77 (6) (
        public 'name' -> string (4) "col1"
        public 'type' -> string (7) "VARCHAR"
        public 'max_length' -> null
        public 'default' -> string (2) "''"
        public 'primary_key' -> boolean false
        public 'nullable' -> boolean false  // MySQLi true
    )
    1 => stdClass#67 (6) (
        public 'name' -> string (4) "col2"
        public 'type' -> string (7) "VARCHAR"
        public 'max_length' -> null
        public 'default' -> string (4) "NULL"
        public 'primary_key' -> boolean false
        public 'nullable' -> boolean true
    )
    2 => stdClass#602 (6) (
        public 'name' -> string (4) "col3"
        public 'type' -> string (7) "VARCHAR"
        public 'max_length' -> null
        public 'default' -> string (4) "NULL"
        public 'primary_key' -> boolean false
        public 'nullable' -> boolean true  // should be false
    )
]

Not directly related, but the all max_length values are incorrect on SQLite3.

[michalsn]

Seems like a bug to me.

[kenjis]

Rebased and now this PR removes only unneeded test code.

[MGatner]

Looks good, thanks!