fix(prefer-text-field): allow varchar without a length (#138)

We shouldn't warn about varchar without a length specified since it is
equivalent to text, which the docs outline:

> The notations varchar(n) and char(n) are aliases for
> character varying(n) and character(n), respectively. character without
> length specifier is equivalent to character(1). If character varying
> is used without length specifier, the type accepts strings of any
> size. The latter is a PostgreSQL extension.

https://www.postgresql.org/docs/current/datatype-character.html

rel: #137

Author: sbdchd

linter/src/rules/ban_drop_column.rs

@@ -18,14 +18,13 @@ pub fn ban_drop_column(tree: &[RootStmt]) -> Vec<RuleViolation> {
             },
             Stmt::AlterTableStmt(stmt) => {
                 for cmd in &stmt.cmds {
-                    if let AlterTableCmds::AlterTableCmd(cmd) = cmd {
-                        if cmd.subtype == AlterTableType::DropColumn {
-                            errs.push(RuleViolation::new(
-                                RuleViolationKind::BanDropColumn,
-                                raw_stmt.into(),
-                                None,
-                            ))
-                        }
+                    let AlterTableCmds::AlterTableCmd(cmd) = cmd;
+                    if cmd.subtype == AlterTableType::DropColumn {
+                        errs.push(RuleViolation::new(
+                            RuleViolationKind::BanDropColumn,
+                            raw_stmt.into(),
+                            None,
+                        ))
                     }
                 }
             }

linter/src/rules/prefer_text_field.rs

@@ -37,7 +37,7 @@ pub fn prefer_text_field(tree: &[RootStmt]) -> Vec<RuleViolation> {
 fn check_column_def(errs: &mut Vec<RuleViolation>, raw_stmt: &RawStmt, column_def: &ColumnDef) {
     let ColumnDefTypeName::TypeName(type_name) = &column_def.type_name;
     for QualifiedName::String(field_type_name) in &type_name.names {
-        if field_type_name.str == "varchar" {
+        if field_type_name.str == "varchar" && !type_name.typmods.is_empty() {
             errs.push(RuleViolation::new(
                 RuleViolationKind::PreferTextField,
                 raw_stmt.into(),
@@ -192,4 +192,13 @@ COMMIT;
         assert!(!data.is_empty());
         assert_debug_snapshot!(data);
     }
+
+    #[test]
+    fn allow_varchar_without_specified_limit() {
+        let ok_sql = r#"
+    CREATE TABLE IF NOT EXISTS foo_table(bar_col varchar);
+    "#;
+        let res = check_sql(ok_sql, &[]);
+        assert_eq!(res, Ok(vec![]));
+    }
 }