code: def test_get_topk_most_similar_users(spark):
      # same df as in tests/unit/recommenders/models/test_sar_singlenode.py
      train_pd = pd.DataFrame(
          {
              "user_id": [1, 1, 2, 2, 3, 3, 3, 3, 4, 4],
              "item_id": [1, 2, 1, 2, 3, 4, 5, 6, 1, 2],
              "rating": [
                  3.0,
                  4.0,
                  3.0,
                  4.0,
                  3.0,
                  2.0,
                  1.0,
                  5.0,
                  5.0,
                  1.0,
              ],
          }
      )
      train_df = spark.createDataFrame(train_pd)
  
      model = SARPlus(
          spark,
          col_user="user_id",
          col_item="item_id",
          col_rating="rating",
          col_timestamp="timestamp",
          similarity_type="jaccard",
      )
      model.fit(train_df)
  
      actual = model.get_topk_most_similar_users(
          test=train_df, user=1, top_k=1
      ).toPandas()
      expected = pd.DataFrame(
          {
              "user_id": [2],
              "similarity": [25.0],
          }
      )
      assert_frame_equal(expected, actual, check_dtype=False)
  
      actual = model.get_topk_most_similar_users(
          test=train_df, user=2, top_k=1
      ).toPandas()
      expected = pd.DataFrame(
          {
              "user_id": [1],
              "similarity": [25.0],
          }
      )
      assert_frame_equal(expected, actual, check_dtype=False)
  
      actual = model.get_topk_most_similar_users(
          test=train_df, user=1, top_k=2
      ).toPandas()
      expected = pd.DataFrame(
          {
              "user_id": [2, 4],
              "similarity": [25.0, 19.0],
          }
      )
      assert_frame_equal(expected, actual, check_dtype=False)
  
imports: import math
  from pathlib import Path
  import numpy
  import pandas
  from pyspark.sql import SparkSession
  import pytest
  from pandas.testing import assert_frame_equal
  from pysarplus import SARPlus, SARModel
label_desc: Use image node_id 16 for calling a global function with example usage: test_get_topk_most_similar_users(spark) without return types