linter: fix regression in adding_not_null_field related to v2 rewrite (#520)

I think the changes from #412 / 360e3ee didn't make it into the v2 codebase.

rel: #519

Author: sbdchd

crates/squawk_linter/src/rules/adding_not_null_field.rs

@@ -3,12 +3,9 @@ use squawk_syntax::{
     Parse, SourceFile,
 };
 
-use crate::{Linter, Rule, Version, Violation};
+use crate::{Linter, Rule, Violation};
 
 pub(crate) fn adding_not_null_field(ctx: &mut Linter, parse: &Parse<SourceFile>) {
-    if ctx.settings.pg_version >= Version::new(11, 0, 0) {
-        return;
-    }
     let file = parse.tree();
     for stmt in file.stmts() {
         if let ast::Stmt::AlterTable(alter_table) = stmt {
@@ -38,7 +35,7 @@ pub(crate) fn adding_not_null_field(ctx: &mut Linter, parse: &Parse<SourceFile>)
 mod test {
     use insta::assert_debug_snapshot;
 
-    use crate::{Linter, Rule, Version};
+    use crate::{Linter, Rule};
 
     #[test]
     fn set_not_null() {
@@ -47,7 +44,6 @@ ALTER TABLE "core_recipe" ALTER COLUMN "foo" SET NOT NULL;
         "#;
         let file = squawk_syntax::SourceFile::parse(sql);
         let mut linter = Linter::from([Rule::AddingNotNullableField]);
-        linter.settings.pg_version = Version::new(10, 0, 0);
         let errors = linter.lint(file, sql);
         assert!(!errors.is_empty());
         assert_debug_snapshot!(errors);
@@ -96,4 +92,20 @@ COMMIT;
         let errors = linter.lint(file, sql);
         assert!(errors.is_empty());
     }
+
+    #[test]
+    fn regression_gh_issue_519() {
+        let sql = r#"
+BEGIN;
+-- Running upgrade a -> b
+ALTER TABLE my_table ALTER COLUMN my_column SET NOT NULL;
+UPDATE alembic_version SET version_num='b' WHERE alembic_version.version_num = 'a';
+COMMIT;
+        "#;
+        let file = squawk_syntax::SourceFile::parse(sql);
+        let mut linter = Linter::from([Rule::AddingNotNullableField]);
+        let errors = linter.lint(file, sql);
+        assert!(!errors.is_empty());
+        assert_debug_snapshot!(errors);
+    }
 }

crates/squawk_linter/src/rules/snapshots/squawk_linter__rules__adding_not_null_field__test__regression_gh_issue_519.snap

@@ -0,0 +1,14 @@
+---
+source: crates/squawk_linter/src/rules/adding_not_null_field.rs
+expression: errors
+---
+[
+    Violation {
+        code: AddingNotNullableField,
+        message: "Setting a column `NOT NULL` blocks reads while the table is scanned.",
+        text_range: 78..90,
+        help: Some(
+            "Make the field nullable and use a `CHECK` constraint instead.",
+        ),
+    },
+]