Add tests for migrations

public/app/plugins/datasource/grafana-postgresql-datasource/migrations.test.ts

@@ -0,0 +1,82 @@
+import { QueryFormat, SQLQuery } from '@grafana/sql';
+
+import { migrateVariableQuery } from './migrations';
+
+describe('migrateVariableQuery', () => {
+  describe('when given a string query (legacy format)', () => {
+    it('should convert to SQLQuery format with rawSql and query fields', () => {
+      const result = migrateVariableQuery('SELECT hostname FROM hosts');
+
+      expect(result.rawSql).toBe('SELECT hostname FROM hosts');
+      expect(result.query).toBe('SELECT hostname FROM hosts');
+      expect(result.refId).toBe('SQLVariableQueryEditor-VariableQuery');
+    });
+
+    it('should handle empty string', () => {
+      const result = migrateVariableQuery('');
+
+      expect(result.rawSql).toBe('');
+      expect(result.query).toBe('');
+    });
+
+    it('should handle complex SQL queries', () => {
+      const complexQuery = `SELECT hostname AS __text, id AS __value FROM hosts WHERE region = 'us-east-1'`;
+      const result = migrateVariableQuery(complexQuery);
+
+      expect(result.rawSql).toBe(complexQuery);
+      expect(result.query).toBe(complexQuery);
+    });
+  });
+
+  describe('when given an SQLQuery object', () => {
+    it('should preserve the rawSql and add query field', () => {
+      const sqlQuery = {
+        refId: 'A',
+        rawSql: 'SELECT id FROM table',
+      };
+      const result = migrateVariableQuery(sqlQuery);
+
+      expect(result.rawSql).toBe('SELECT id FROM table');
+      expect(result.query).toBe('SELECT id FROM table');
+      expect(result.refId).toBe('A');
+    });
+
+    it('should handle SQLQuery with empty rawSql', () => {
+      const sqlQuery = {
+        refId: 'A',
+        rawSql: '',
+      };
+      const result = migrateVariableQuery(sqlQuery);
+
+      expect(result.rawSql).toBe('');
+      expect(result.query).toBe('');
+    });
+
+    it('should handle SQLQuery without rawSql', () => {
+      const sqlQuery = {
+        refId: 'A',
+      };
+      const result = migrateVariableQuery(sqlQuery);
+
+      expect(result.query).toBe('');
+    });
+
+    it('should preserve all existing SQLQuery properties', () => {
+      const sqlQuery: SQLQuery = {
+        refId: 'B',
+        rawSql: 'SELECT * FROM users',
+        format: QueryFormat.Table,
+        table: 'users',
+        dataset: 'mydb',
+      };
+      const result = migrateVariableQuery(sqlQuery);
+
+      expect(result.refId).toBe('B');
+      expect(result.rawSql).toBe('SELECT * FROM users');
+      expect(result.query).toBe('SELECT * FROM users');
+      expect(result.format).toBe(QueryFormat.Table);
+      expect(result.table).toBe('users');
+      expect(result.dataset).toBe('mydb');
+    });
+  });
+});