1 files changed, 22 insertions, 0 deletions
diff --git a/third_party/rust/id-arena/tests/readme_up_to_date.rs b/third_party/rust/id-arena/tests/readme_up_to_date.rs
new file mode 100644
index 0000000000..38af909e31
--- /dev/null
+++ b/third_party/rust/id-arena/tests/readme_up_to_date.rs
@@ -0,0 +1,22 @@
+use std::fs;
+use std::process::Command;
+
+#[test]
+fn cargo_readme_up_to_date() {
+    println!("Checking that `cargo readme > README.md` is up to date...");
+
+    let expected = Command::new("cargo")
+        .arg("readme")
+        .current_dir(env!("CARGO_MANIFEST_DIR"))
+        .output()
+        .expect("should run `cargo readme` OK")
+        .stdout;
+    let expected = String::from_utf8_lossy(&expected);
+
+    let actual = fs::read_to_string(concat!(env!("CARGO_MANIFEST_DIR"), "/README.md"))
+        .expect("should read README.md OK");
+
+    if actual != expected {
+        panic!("Run `cargo readme > README.md` to update README.md");
+    }
+}