add tests of --no-default-features to CI

.github/workflows/rust.yml

@@ -112,6 +112,8 @@ jobs:
           cd arrow
           # re-run tests on arrow workspace with additional features
           cargo test --features=prettyprint
+          # run test on arrow with minimal set of features
+          cargo test --no-default-features
           cargo run --example builders
           cargo run --example dynamic_types
           cargo run --example read_csv

arrow/src/util/string_writer.rs

@@ -23,6 +23,8 @@
 //! Example:
 //!
 //! ```
+//! #[cfg(feature = "csv")]
+//! {
 //! use arrow::array::*;
 //! use arrow::csv;
 //! use arrow::datatypes::*;
@@ -58,6 +60,7 @@
 //! let sw = StringWriter::new();
 //! let mut writer = csv::Writer::new(sw);
 //! writer.write(&batch).unwrap();
+//! }
 //! ```
 
 use std::io::{Error, ErrorKind, Result, Write};