Fix nullability in encapsulate

sqlparser/lib/src/analysis/types/graph/type_graph.dart

@@ -149,16 +149,16 @@ class TypeGraph {
   }
 
   ResolvedType? _encapsulate(Iterable<ResolvedType?> targets) {
-    return targets
-        .map((e) => e!.withoutNullabilityInfo)
-        .fold<ResolvedType?>(null, (previous, element) {
+    return targets.fold<ResolvedType?>(null, (previous, element) {
       if (previous == null) return element;
 
       final previousType = previous.type;
-      final elementType = element.type;
+      final elementType = element!.type;
+      final eitherNullable =
+          previous.nullable == true || element.nullable == true;
 
       if (previousType == elementType || elementType == BasicType.nullType) {
-        return previous;
+        return previous.withNullable(eitherNullable);
       }
       if (previousType == BasicType.nullType) return element;
 
@@ -168,7 +168,7 @@ class TypeGraph {
 
       // encapsulate two different numeric types to real
       if (isIntOrNumeric(previousType) && isIntOrNumeric(elementType)) {
-        return const ResolvedType(type: BasicType.real);
+        return ResolvedType(type: BasicType.real, nullable: eitherNullable);
       }
 
       // fallback to text if everything else fails

sqlparser/test/analysis/regress_917_test.dart

@@ -1,39 +0,0 @@
-import 'package:sqlparser/sqlparser.dart';
-import 'package:test/test.dart';
-
-void main() {
-  test('regression test for #917', () {
-    final engine = SqlEngine()
-      ..registerTableFromSql('CREATE TABLE Shops (id INTEGER);')
-      ..registerTableFromSql(
-          'CREATE TABLE Sales (shop_id INTEGER, date INTEGER, amount REAL);');
-
-    final result = engine.analyze('''
-      SELECT
-          Shops.id,
-          SalesYesterday.amount AS amount_yesterday,
-          SalesToday.amount AS amount_today
-      FROM Sales AS SalesYesterday,
-      (
-          SELECT SalesToday.amount AS amount, SalesToday.shop_id AS shop_id
-          FROM Sales AS SalesToday
-          LEFT JOIN Shops ON SalesToday.shop_id = Shops.id
-          WHERE SalesToday.date = 8
-      ) AS SalesToday
-      INNER JOIN Shops
-          ON (SalesYesterday.shop_id = Shops.id)
-          AND (SalesToday.shop_id = Shops.id)
-      WHERE SalesYesterday.date = 9
-      ORDER BY Shops.id;
-      ''');
-
-    expect(result.errors, isEmpty);
-  });
-}
-
-extension on SqlEngine {
-  void registerTableFromSql(String createTable) {
-    final stmt = parse(createTable).rootNode as CreateTableStatement;
-    registerTable(schemaReader.read(stmt));
-  }
-}

sqlparser/test/analysis/regression_test.dart

@@ -0,0 +1,90 @@
+import 'package:sqlparser/sqlparser.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('regression test for #917', () {
+    // Test for https://github.com/simolus3/moor/issues/917
+    final engine = SqlEngine()
+      ..registerTableFromSql('CREATE TABLE Shops (id INTEGER);')
+      ..registerTableFromSql(
+          'CREATE TABLE Sales (shop_id INTEGER, date INTEGER, amount REAL);');
+
+    final result = engine.analyze('''
+      SELECT
+          Shops.id,
+          SalesYesterday.amount AS amount_yesterday,
+          SalesToday.amount AS amount_today
+      FROM Sales AS SalesYesterday,
+      (
+          SELECT SalesToday.amount AS amount, SalesToday.shop_id AS shop_id
+          FROM Sales AS SalesToday
+          LEFT JOIN Shops ON SalesToday.shop_id = Shops.id
+          WHERE SalesToday.date = 8
+      ) AS SalesToday
+      INNER JOIN Shops
+          ON (SalesYesterday.shop_id = Shops.id)
+          AND (SalesToday.shop_id = Shops.id)
+      WHERE SalesYesterday.date = 9
+      ORDER BY Shops.id;
+      ''');
+
+    expect(result.errors, isEmpty);
+  });
+
+  test('regression test for #1188', () {
+    // Test for https://github.com/simolus3/moor/issues/1188
+    final engine = SqlEngine(EngineOptions(useMoorExtensions: true))
+      ..registerTableFromSql('''
+        CREATE TABLE IF NOT EXISTS "employees" (
+     	    "id" INTEGER NOT NULL PRIMARY KEY,
+     	    "name" TEXT NOT NULL UNIQUE,
+     	    "manager_id" INTEGER
+     	  );
+      ''')
+      ..registerTableFromSql('''
+        CREATE TABLE IF NOT EXISTS "employee_notes" (
+          "employee_id"	INTEGER NOT NULL PRIMARY KEY,
+          "note" TEXT
+        );
+      ''');
+
+    final result = engine.analyze('''
+      WITH RECURSIVE
+      employeeHierarchy(id, name, manager_id) AS (
+        SELECT id, 
+               name,
+               manager_id
+          FROM employees
+          WHERE manager_id IS NULL
+          UNION ALL
+        SELECT e.id, 
+               e.name,
+               e.manager_id
+          FROM employees e
+          JOIN employeeHierarchy ON e.manager_id = employeeHierarchy.id
+      )
+      SELECT e.id, 
+            e.name,
+            e.manager_id,
+            n.note
+        FROM employeeHierarchy e
+        LEFT OUTER JOIN
+            employee_notes n ON e.id = n.employee_id
+      ORDER BY e.id;
+    ''');
+
+    final select = result.root as SelectStatement;
+    final columns = select.resolvedColumns!;
+
+    expect(columns.map((e) => e.name), ['id', 'name', 'manager_id', 'note']);
+    expect(columns.map((e) => result.typeOf(e).nullable),
+        [false, false, true, true]);
+  });
+}
+
+extension on SqlEngine {
+  void registerTableFromSql(String createTable) {
+    final stmt = parse(createTable).rootNode as CreateTableStatement;
+    registerTable(schemaReader.read(stmt));
+  }
+}