[Data] Remove ordering assumption and unnecessary `override_num_block…

…s` from `test_parquet_roundtrip` (#47550)

`test_parquet_roundtrip` specifies `override_num_blocks`, even though
the argument isn't required for the specific behavior under test (i.e.,
that you can write and then read back Parquet files). Also, the test
implicitly assumes that Ray Data reads files in a particular order.

To ensure we're testing behavior and not implementation, and to make the
test resilient to future code changes, this PR removes the
`override_num_blocks` and updates the code to eliminate ordering.

---------

Signed-off-by: Balaji Veeramani <bveeramani@berkeley.edu>

python/ray/data/tests/test_parquet.py

@@ -1032,22 +1032,27 @@ def test_parquet_write_create_dir(
     ],
 )
 def test_parquet_roundtrip(ray_start_regular_shared, fs, data_path):
-    df1 = pd.DataFrame({"one": [1, 2, 3], "two": ["a", "b", "c"]})
-    df2 = pd.DataFrame({"one": [4, 5, 6], "two": ["e", "f", "g"]})
-    ds = ray.data.from_pandas([df1, df2])
-    ds._set_uuid("data")
     path = os.path.join(data_path, "test_parquet_dir")
     if fs is None:
         os.mkdir(path)
     else:
         fs.create_dir(_unwrap_protocol(path))
+
+    df1 = pd.DataFrame({"one": [1, 2, 3], "two": ["a", "b", "c"]})
+    df2 = pd.DataFrame({"one": [4, 5, 6], "two": ["e", "f", "g"]})
+    ds = ray.data.from_pandas([df1, df2])
     ds.write_parquet(path, filesystem=fs)
-    ds2 = ray.data.read_parquet(path, override_num_blocks=2, filesystem=fs)
-    ds2df = ds2.to_pandas()
-    assert pd.concat([df1, df2], ignore_index=True).equals(ds2df)
+
+    ds2 = ray.data.read_parquet(path, filesystem=fs)
+
+    read_data = set(ds2.to_pandas().itertuples(index=False))
+    written_data = set(pd.concat([df1, df2]).itertuples(index=False))
+    assert read_data == written_data
+
     # Test metadata ops.
     for block, meta in ds2._plan.execute().blocks:
         BlockAccessor.for_block(ray.get(block)).size_bytes() == meta.size_bytes
+
     if fs is None:
         shutil.rmtree(path)
     else: