RUST-893 Add connectivity tests for Atlas serverless load-balanced instances (#505)

Author: abr-egn

.evergreen/config.yml

@@ -389,6 +389,8 @@ functions:
           export MONGO_ATLAS_TESTS=1
           export MONGO_ATLAS_FREE_TIER_REPL_URI='${MONGO_ATLAS_FREE_TIER_REPL_URI}'
           export MONGO_ATLAS_FREE_TIER_REPL_URI_SRV='${MONGO_ATLAS_FREE_TIER_REPL_URI_SRV}'
+          export MONGO_ATLAS_SERVERLESS_URI='${MONGO_ATLAS_SERVERLESS_URI}'
+          export MONGO_ATLAS_SERVERLESS_URI_SRV='${MONGO_ATLAS_SERVERLESS_URI_SRV}'
           ASYNC_RUNTIME=${ASYNC_RUNTIME} .evergreen/run-atlas-tests.sh
 
   "run ocsp test":

src/test/atlas_connectivity.rs

@@ -49,3 +49,19 @@ async fn atlas_repl_set_srv() {
     )
     .await;
 }
+
+#[cfg_attr(feature = "tokio-runtime", tokio::test)]
+#[cfg_attr(feature = "async-std-runtime", async_std::test)]
+async fn atlas_serverless() {
+    run_test("MONGO_ATLAS_SERVERLESS_URI", None).await;
+}
+
+#[cfg_attr(feature = "tokio-runtime", tokio::test)]
+#[cfg_attr(feature = "async-std-runtime", async_std::test)]
+async fn atlas_serverless_srv() {
+    run_test(
+        "MONGO_ATLAS_SERVERLESS_URI_SRV",
+        Some(ResolverConfig::cloudflare()),
+    )
+    .await;
+}