minor: fix doctest that runs accidentally

.github/workflows/docs_pr.yaml

@@ -0,0 +1,54 @@
+# 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.
+
+name: Docs
+
+concurrency:
+  group: ${{ github.repository }}-${{ github.head_ref || github.sha }}-${{ github.workflow }}
+  cancel-in-progress: true
+
+on:
+  push:
+    paths:
+      - "docs/**"
+  pull_request:
+    paths:
+      - "docs/**"
+  # manual trigger
+  # https://docs.github.com/en/actions/managing-workflow-runs/manually-running-a-workflow
+  workflow_dispatch:
+
+jobs:
+  # Run doc tests
+  linux-test-doc:
+    name: cargo doctest (amd64)
+    runs-on: ubuntu-latest
+    container:
+      image: amd64/rust
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          submodules: true
+      - name: Setup Rust toolchain
+        uses: ./.github/actions/setup-builder
+        with:
+          rust-version: stable
+      # Note: this does not include dictionary_expressions to reduce codegen
+      - name: Run doctests
+        run: cargo test --doc --features avro,jit,scheduler,json
+      - name: Verify Working Directory Clean
+        run: git diff --exit-code

docs/source/user-guide/example-usage.md

@@ -175,12 +175,13 @@ codegen-units = 1
 
 Then, in `main.rs.` update the memory allocator with the below after your imports:
 
-```rust
+```rust,ignore
 use datafusion::prelude::*;
 
 #[global_allocator]
 static ALLOC: snmalloc_rs::SnMalloc = snmalloc_rs::SnMalloc;
 
+#[tokio::main]
 async fn main() -> datafusion::error::Result<()> {
   Ok(())
 }
@@ -195,6 +196,6 @@ rustup toolchain install nightly
 Based on the instruction set architecture you are building on you will want to configure the `target-cpu` as well, ideally
 with `native` or at least `avx2`.
 
-```
+```shell
 RUSTFLAGS='-C target-cpu=native' cargo +nightly run --release
 ```