Add a test for tokio-postgres client to the driver test suite.

It is fully supported. To enable TLS, though, it requires some extra
glue code, and a dependency to a TLS library.

test_runner/pg_clients/rust/tokio-postgres/.dockerignore

@@ -0,0 +1 @@
+target/

test_runner/pg_clients/rust/tokio-postgres/.gitignore

@@ -0,0 +1 @@
+target/

test_runner/pg_clients/rust/tokio-postgres/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "rust-neon-example"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+native-tls = "0.2.11"
+postgres-native-tls = "0.5.0"
+tokio = { version = "1.26", features=["rt", "macros"] }
+tokio-postgres = "0.7.7"
+
+
+# This is not part of the main 'neon' workspace
+[workspace]

test_runner/pg_clients/rust/tokio-postgres/Dockerfile

@@ -0,0 +1,6 @@
+FROM rust:1.67
+WORKDIR /source
+
+COPY . .
+RUN cargo build
+CMD ["/source/target/debug/rust-neon-example"]

test_runner/pg_clients/rust/tokio-postgres/src/main.rs

@@ -0,0 +1,43 @@
+use std::env::VarError;
+use tokio_postgres;
+
+fn get_env(key: &str) -> String {
+    match std::env::var(key) {
+        Ok(val) => val,
+        Err(VarError::NotPresent) => panic!("{key} env variable not set"),
+        Err(VarError::NotUnicode(_)) => panic!("{key} is not valid unicode"),
+    }
+}
+
+#[tokio::main(flavor = "current_thread")]
+async fn main() -> Result<(), tokio_postgres::Error> {
+    let host = get_env("NEON_HOST");
+    let database = get_env("NEON_DATABASE");
+    let user = get_env("NEON_USER");
+    let password = get_env("NEON_PASSWORD");
+
+    let url = format!("postgresql://{user}:{password}@{host}/{database}");
+
+    // Use the native TLS implementation (Neon requires TLS)
+    let tls_connector =
+        postgres_native_tls::MakeTlsConnector::new(native_tls::TlsConnector::new().unwrap());
+
+    // Connect to the database.
+    let (client, connection) = tokio_postgres::connect(&url, tls_connector).await?;
+
+    // The connection object performs the actual communication with the database,
+    // so spawn it off to run on its own.
+    tokio::spawn(async move {
+        if let Err(e) = connection.await {
+            eprintln!("connection error: {}", e);
+        }
+    });
+
+    let result = client.query("SELECT 1", &[]).await?;
+
+    let value: i32 = result[0].get(0);
+    assert_eq!(value, 1);
+    println!("{value}");
+
+    Ok(())
+}

test_runner/pg_clients/test_pg_clients.py

@@ -13,6 +13,7 @@ from fixtures.utils import subprocess_capture
     [
         "csharp/npgsql",
         "java/jdbc",
+        "rust/tokio-postgres",
         "python/asyncpg",
         "python/pg8000",
         pytest.param(