function assertIndexTables(schema, tableNames) {
  schema.tables().forEach(function(tableSchema) {
    tableSchema.getIndices().forEach(function(indexSchema) {
      assertEquals(
          tableSchema.persistentIndex(),
          tableNames.has(indexSchema.getNormalizedName()));
    });

    // Checking whether backing store for RowId index was created.
    assertEquals(
        tableSchema.persistentIndex(),
        tableNames.has(tableSchema.getRowIdIndexName()));
  });
}
Asserts that an object store was created for each lf.schema.Index instance
that belongs to a user-defined table that has "persistentIndex" enabled.
@param {!lf.schema.Database} schema The database schema being tested.
@param {!lf.structs.Set<string>} tableNames The names of the tables that
    were created in the backing store.