Fix broken serde feature

.github/workflows/rust.yml

@@ -183,7 +183,7 @@ jobs:
         with:
           rust-version: stable
       - name: Run tests (excluding doctests)
-        run: cargo test --profile ci --exclude datafusion-examples --exclude ffi_example_table_provider --exclude datafusion-benchmarks --workspace --lib --tests --bins --features avro,json,backtrace,integration-tests
+        run: cargo test --profile ci --exclude datafusion-examples --exclude ffi_example_table_provider --exclude datafusion-benchmarks --workspace --lib --tests --bins --features serde,avro,json,backtrace,integration-tests
       - name: Verify Working Directory Clean
         run: git diff --exit-code
 

datafusion/core/Cargo.toml

@@ -79,7 +79,12 @@ recursive_protection = [
     "datafusion-physical-optimizer/recursive_protection",
     "datafusion-sql/recursive_protection",
 ]
-serde = ["dep:serde"]
+serde = [
+    "dep:serde",
+    # Enable `#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]`
+    # statements in `arrow-schema` crate
+    "arrow-schema/serde",
+]
 string_expressions = ["datafusion-functions/string_expressions"]
 unicode_expressions = [
     "datafusion-sql/unicode_expressions",

datafusion/core/tests/core_integration.rs

@@ -42,8 +42,13 @@ mod custom_sources_cases;
 /// Run all tests that are found in the `optimizer` directory
 mod optimizer;
 
+/// Run all tests that are found in the `physical_optimizer` directory
 mod physical_optimizer;
 
+/// Run all tests that are found in the `serde` directory
+mod serde;
+
+/// Run all tests that are found in the `catalog` directory
 mod catalog;
 
 #[cfg(test)]

datafusion/core/tests/serde/mod.rs

@@ -0,0 +1,34 @@
+// 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.
+
+/// Ensure `serde` feature from `arrow-schema` crate is re-exported.
+#[test]
+#[cfg(feature = "serde")]
+fn ensure_serde_support() {
+    use datafusion::arrow::datatypes::DataType;
+
+    #[derive(Debug, PartialEq, serde::Serialize, serde::Deserialize)]
+    struct WrappingStruct(DataType);
+
+    let boolean = WrappingStruct(DataType::Boolean);
+
+    let serialized = serde_json::to_string(&boolean).unwrap();
+    assert_eq!("\"Boolean\"", serialized);
+
+    let deserialized = serde_json::from_str(&serialized).unwrap();
+    assert_eq!(boolean, deserialized);
+}