add guard test for automerge imports

1 files changed, 54 insertions, 0 deletions

diff --git a/src/document/mod.rs b/src/document/mod.rs
index d7d3e88..1612145 100644
--- a/src/document/mod.rs
+++ b/src/document/mod.rs
@@ -12,3 +12,57 @@ pub(crate) mod lock;
 pub(crate) mod meta;
 pub(crate) mod replica;
 pub(crate) mod store;
+
+#[cfg(test)]
+mod tests {
+    use std::path::{Path, PathBuf};
+
+    /// Every `.rs` file under `dir`.
+    fn sources(dir: &Path, out: &mut Vec<PathBuf>) {
+        for entry in std::fs::read_dir(dir).unwrap() {
+            let path = entry.unwrap().path();
+            if path.is_dir() {
+                sources(&path, out);
+            } else if path.extension().is_some_and(|extension| extension == "rs") {
+                out.push(path);
+            }
+        }
+    }
+
+    /// Automerge is used only in `document`, `remake` and the sync session
+    /// (`state/session.rs`); the rest of the node names its types as `document`
+    /// re-exports them and works through `document` (`architecture.md`, The document).
+    #[test]
+    fn automerge_stays_behind_document() {
+        let src = Path::new(env!("CARGO_MANIFEST_DIR")).join("src");
+        let allowed = [
+            src.join("document"),
+            src.join("remake"),
+            src.join("state").join("session.rs"),
+        ];
+        let mut files = Vec::new();
+        sources(&src, &mut files);
+        let mut found = Vec::new();
+        for file in files
+            .iter()
+            .filter(|file| !allowed.iter().any(|allowed| file.starts_with(allowed)))
+        {
+            let text = std::fs::read_to_string(file).unwrap();
+            for (number, line) in text.lines().enumerate() {
+                if line.contains("automerge::") || line.trim_start().starts_with("use automerge") {
+                    found.push(format!(
+                        "{}:{}: {}",
+                        file.display(),
+                        number + 1,
+                        line.trim()
+                    ));
+                }
+            }
+        }
+        assert!(
+            found.is_empty(),
+            "Automerge used outside `document`:\n{}",
+            found.join("\n")
+        );
+    }
+}