code: def test_join_float64_float32(self):
      a = DataFrame(
          np.random.default_rng(2).standard_normal((10, 2)),
          columns=["a", "b"],
          dtype=np.float64,
      )
      b = DataFrame(
          np.random.default_rng(2).standard_normal((10, 1)),
          columns=["c"],
          dtype=np.float32,
      )
      joined = a.join(b)
      assert joined.dtypes["a"] == "float64"
      assert joined.dtypes["b"] == "float64"
      assert joined.dtypes["c"] == "float32"
  
      a = np.random.default_rng(2).integers(0, 5, 100).astype("int64")
      b = np.random.default_rng(2).random(100).astype("float64")
      c = np.random.default_rng(2).random(100).astype("float32")
      df = DataFrame({"a": a, "b": b, "c": c})
      xpdf = DataFrame({"a": a, "b": b, "c": c})
      s = DataFrame(
          np.random.default_rng(2).random(5).astype("float32"),
          columns=["md"],
      )
      rs = df.merge(s, left_on="a", right_index=True)
      assert rs.dtypes["a"] == "int64"
      assert rs.dtypes["b"] == "float64"
      assert rs.dtypes["c"] == "float32"
      assert rs.dtypes["md"] == "float32"
  
      xp = xpdf.merge(s, left_on="a", right_index=True)
      tm.assert_frame_equal(rs, xp)
  
imports: import re
  import numpy
  import pytest
  import pandas.util._test_decorators
  import pandas
  from pandas import Categorical, DataFrame, Index, MultiIndex, Series, Timestamp, bdate_range, concat, merge, option_context
  import pandas._testing
label_desc: Use image node_id 28 for calling the TestJoin obj's underlying member method code with example usage: obj.test_join_float64_float32() without return types