chore: add docs, part of #37

- add pragma `#![warn(missing_docs)]` to the following
  - `arrow-flight`
  - `arrow-integration-test`
  - `arrow-integration-testing`

arrow-flight/examples/flight_sql_server.rs

@@ -19,6 +19,7 @@ use arrow_flight::sql::server::PeekableFlightDataStream;
 use arrow_flight::sql::DoPutPreparedStatementResult;
 use base64::prelude::BASE64_STANDARD;
 use base64::Engine;
+use core::str;
 use futures::{stream, Stream, TryStreamExt};
 use once_cell::sync::Lazy;
 use prost::Message;
@@ -168,7 +169,7 @@ impl FlightSqlService for FlightSqlServiceImpl {
         let bytes = BASE64_STANDARD
             .decode(base64)
             .map_err(|e| status!("authorization not decodable", e))?;
-        let str = String::from_utf8(bytes).map_err(|e| status!("authorization not parsable", e))?;
+        let str = str::from_utf8(&bytes).map_err(|e| status!("authorization not parsable", e))?;
         let parts: Vec<_> = str.split(':').collect();
         let (user, pass) = match parts.as_slice() {
             [user, pass] => (user, pass),

arrow-flight/src/bin/flight_sql_client.rs

@@ -26,6 +26,7 @@ use arrow_flight::{
 };
 use arrow_schema::Schema;
 use clap::{Parser, Subcommand};
+use core::str;
 use futures::TryStreamExt;
 use tonic::{
     metadata::MetadataMap,
@@ -421,7 +422,7 @@ fn log_metadata(map: &MetadataMap, what: &'static str) {
                     "{}: {}={}",
                     what,
                     k.as_str(),
-                    String::from_utf8_lossy(v.as_ref()),
+                    str::from_utf8(v.as_ref()).unwrap(),
                 );
             }
         }

arrow-flight/src/decode.rs

@@ -388,33 +388,38 @@ struct FlightStreamState {
 /// FlightData and the decoded payload (Schema, RecordBatch), if any
 #[derive(Debug)]
 pub struct DecodedFlightData {
+    /// The original FlightData message
     pub inner: FlightData,
+    /// The decoded payload
     pub payload: DecodedPayload,
 }
 
 impl DecodedFlightData {
+    /// Create a new DecodedFlightData with no payload
     pub fn new_none(inner: FlightData) -> Self {
         Self {
             inner,
             payload: DecodedPayload::None,
         }
     }
 
+    /// Create a new DecodedFlightData with a [`Schema`] payload
     pub fn new_schema(inner: FlightData, schema: SchemaRef) -> Self {
         Self {
             inner,
             payload: DecodedPayload::Schema(schema),
         }
     }
 
+    /// Create a new [`DecodedFlightData`] with a [`RecordBatch`] payload
     pub fn new_record_batch(inner: FlightData, batch: RecordBatch) -> Self {
         Self {
             inner,
             payload: DecodedPayload::RecordBatch(batch),
         }
     }
 
-    /// return the metadata field of the inner flight data
+    /// Return the metadata field of the inner flight data
     pub fn app_metadata(&self) -> Bytes {
         self.inner.app_metadata.clone()
     }

arrow-flight/src/encode.rs

@@ -144,6 +144,7 @@ impl Default for FlightDataEncoderBuilder {
 }
 
 impl FlightDataEncoderBuilder {
+    /// Create a new [`FlightDataEncoderBuilder`].
     pub fn new() -> Self {
         Self::default()
     }
@@ -1403,7 +1404,7 @@ mod tests {
         let input_rows = batch.num_rows();
 
         let split = split_batch_for_grpc_response(batch.clone(), max_flight_data_size_bytes);
-        let sizes: Vec<_> = split.iter().map(|batch| batch.num_rows()).collect();
+        let sizes: Vec<_> = split.iter().map(RecordBatch::num_rows).collect();
         let output_rows: usize = sizes.iter().sum();
 
         assert_eq!(sizes, expected_sizes, "mismatch for {batch:?}");

arrow-flight/src/error.rs

@@ -37,6 +37,7 @@ pub enum FlightError {
 }
 
 impl FlightError {
+    /// Generate a new `FlightError::ProtocolError` variant.
     pub fn protocol(message: impl Into<String>) -> Self {
         Self::ProtocolError(message.into())
     }
@@ -98,6 +99,7 @@ impl From<FlightError> for tonic::Status {
     }
 }
 
+/// Result type for the Apache Arrow Flight crate
 pub type Result<T> = std::result::Result<T, FlightError>;
 
 #[cfg(test)]

arrow-flight/src/lib.rs

@@ -37,6 +37,7 @@
 //!
 //! [Flight SQL]: https://arrow.apache.org/docs/format/FlightSql.html
 #![allow(rustdoc::invalid_html_tags)]
+#![warn(missing_docs)]
 
 use arrow_ipc::{convert, writer, writer::EncodedData, writer::IpcWriteOptions};
 use arrow_schema::{ArrowError, Schema};
@@ -52,6 +53,8 @@ type ArrowResult<T> = std::result::Result<T, ArrowError>;
 
 #[allow(clippy::all)]
 mod gen {
+    // Since this file is auto-generated, we suppress all warnings
+    #![allow(missing_docs)]
     include!("arrow.flight.protocol.rs");
 }
 
@@ -125,6 +128,7 @@ use flight_descriptor::DescriptorType;
 
 /// SchemaAsIpc represents a pairing of a `Schema` with IpcWriteOptions
 pub struct SchemaAsIpc<'a> {
+    /// Data type representing a schema and its IPC write options
     pub pair: (&'a Schema, &'a IpcWriteOptions),
 }
 
@@ -682,6 +686,7 @@ impl PollInfo {
 }
 
 impl<'a> SchemaAsIpc<'a> {
+    /// Create a new `SchemaAsIpc` from a `Schema` and `IpcWriteOptions`
     pub fn new(schema: &'a Schema, options: &'a IpcWriteOptions) -> Self {
         SchemaAsIpc {
             pair: (schema, options),