[GitHub] [arrow] jonkeane commented on a change in pull request #9118: [WIP] Arrow 10623: [R] Version 1.0.1 breaks data.frame attributes when reading file written by 2.0.0

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jonkeane commented on a change in pull request #9118:
URL: https://github.com/apache/arrow/pull/9118#discussion_r553018847



##########
File path: r/tests/testthat/test-parquet-compatibility.R
##########
@@ -0,0 +1,45 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# TODO: skip mostly? Or use this for backwards compat?
+
+pq_file <- test_path("parquets/data-arrow2.parquet")
+
+test_that("reading a known Parquet file to dataframe", {
+  df <- read_parquet(pq_file)
+  expect_data_frame(df, data.frame(col1 = 1:10))
+  expect_identical(dim(df), c(10L, 1L))
+
+  tab <- read_parquet(pq_file, as_data_frame = FALSE)
+  expect_s3_class(tab, "Table")
+  expect_equal(
+    # unserialize like .unserialize_arrow_r_metadata does (though we can't call
+    # it directly because it's not exported)
+    unserialize(charToRaw(tab$metadata$r)),
+    list(
+      attributes = list(class = "data.frame"),
+      columns = list(col1 = NULL)
+    )
+  )
+
+  # test the workaround
+  tab$metadata$r <- NULL

Review comment:
       Yeah, this file isn't what it needs to be for the golden tests we were thinking about — that's my next step. This is basically as it was when I was using it for forward compatibility




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