Add sanity test

An integration sanity test is added to
ensure that all RBS included in the repo can be
correctly parsed.

Author: soutaro

rust/ruby-rbs/tests/sanity.rs

@@ -0,0 +1,47 @@
+use std::path::Path;
+
+use ruby_rbs::node::parse;
+
+fn collect_rbs_files(dir: &Path) -> Vec<std::path::PathBuf> {
+    let mut files = Vec::new();
+
+    for entry in std::fs::read_dir(dir).unwrap() {
+        let entry = entry.unwrap();
+        let path = entry.path();
+
+        if path.is_dir() {
+            files.extend(collect_rbs_files(&path));
+        } else if path.extension().is_some_and(|ext| ext == "rbs") {
+            files.push(path);
+        }
+    }
+
+    files
+}
+
+#[test]
+fn all_included_rbs_can_be_parsed() {
+    let repo_root = Path::new(env!("CARGO_MANIFEST_DIR")).join("../..");
+    let dirs = [repo_root.join("core"), repo_root.join("stdlib")];
+
+    let mut files: Vec<_> = dirs.iter().flat_map(|d| collect_rbs_files(d)).collect();
+    files.sort();
+    assert!(!files.is_empty());
+
+    let mut failures = Vec::new();
+
+    for file in &files {
+        let content = std::fs::read_to_string(file).unwrap();
+
+        if let Err(e) = parse(content.as_bytes()) {
+            failures.push(format!("{}: {}", file.display(), e));
+        }
+    }
+
+    assert!(
+        failures.is_empty(),
+        "Failed to parse {} RBS file(s):\n{}",
+        failures.len(),
+        failures.join("\n")
+    );
+}