fix(api-gateway): Fix member sql extraction in meta?extended (cube-js#9826)

Author: bsod90

packages/cubejs-api-gateway/src/helpers/transformMetaExtended.ts

@@ -4,7 +4,7 @@ function stringifyMemberSql(sql?: () => string) {
   }
 
   const sqlStr = sql.toString();
-  return sqlStr.substring(sqlStr.indexOf('=>') + 3);
+  return sqlStr.substring(sqlStr.indexOf('=>') + 2).trim();
 }
 
 type MemberPath = {

packages/cubejs-api-gateway/test/helpers/transformMetaExtended.test.ts

@@ -162,6 +162,37 @@ describe('transformMetaExtended helpers', () => {
     expect(handledCube).toHaveProperty('dimensions');
   });
 
+  test('transformCube - extends field preservation', () => {
+    const mockCubeDefinitions = {
+      BaseCube: { extends: () => 'BaseCube' },
+      ExtendedCube: { extends: () => 'ExtendedCube' },
+      AnotherCube: { extends: () => 'AnotherCube' },
+      TestCube: { extends: () => 'TestCube' },
+      SampleCube: { extends: () => 'SampleCube' }
+    };
+
+    const mockCubes = [
+      { name: 'BaseCube' },
+      { name: 'ExtendedCube' },
+      { name: 'AnotherCube' },
+      { name: 'TestCube' },
+      { name: 'SampleCube' }
+    ];
+
+    mockCubes.forEach(cube => {
+      const transformedCube = transformCube(cube, mockCubeDefinitions);
+      expect(transformedCube).toBeDefined();
+      expect(transformedCube.extends).toBe(`'${cube.name}'`);
+    });
+
+    // Specific test cases to verify first letter preservation
+    const baseCube = transformCube({ name: 'BaseCube' }, mockCubeDefinitions);
+    expect(baseCube.extends).toBe('\'BaseCube\'');
+
+    const extendedCube = transformCube({ name: 'ExtendedCube' }, mockCubeDefinitions);
+    expect(extendedCube.extends).toBe('\'ExtendedCube\'');
+  });
+
   test('transformDimension', () => {
     const handledDimension = transformDimension(MOCK_USERS_CUBE.dimensions.id, MOCK_USERS_CUBE);
     expect(handledDimension).toBeDefined();