feat(core): broaden .understandignore starter — Rust test/bench patterns

understand-anything-plugin/packages/core/src/__tests__/ignore-generator.test.ts

@@ -162,6 +162,12 @@ describe("generateStarterIgnoreFile", () => {
       const content = generateStarterIgnoreFile(testDir);
       expect(content).toContain("# bench/");
     });
+
+    it("suggests benches/ directories (Cargo convention)", () => {
+      mkdirSync(join(testDir, "benches"), { recursive: true });
+      const content = generateStarterIgnoreFile(testDir);
+      expect(content).toContain("# benches/");
+    });
   });
 
   describe("language-grouped test file patterns", () => {
@@ -227,25 +233,52 @@ describe("generateStarterIgnoreFile", () => {
       expect(content).toContain("# **/conftest.py");
     });
 
+    it("includes Rust tests.rs per-module extraction convention", () => {
+      const content = generateStarterIgnoreFile(testDir);
+      expect(content).toContain("# Rust");
+      // Rust Book ch. 11.3 pattern — extracted sibling test module.
+      expect(content).toContain("# **/tests.rs");
+    });
+
+    it("includes Rust workspace-style *_test.rs and test_*.rs conventions", () => {
+      const content = generateStarterIgnoreFile(testDir);
+      // Dominant in large workspaces (polkadot-sdk, rust-lang/rust,
+      // solana-labs/solana) where tests colocate with source rather
+      // than living inside inline `#[cfg(test)] mod tests`.
+      expect(content).toContain("# **/test_*.rs");
+      expect(content).toContain("# **/*_test.rs");
+    });
+
+    it("includes Rust criterion / test::Bencher file patterns", () => {
+      const content = generateStarterIgnoreFile(testDir);
+      // Defensive: most Cargo benches live under `benches/` (covered by
+      // the dir rule) but a small fraction of workspaces name benchmark
+      // files with these prefixes/suffixes outside that directory.
+      expect(content).toContain("# **/bench_*.rs");
+      expect(content).toContain("# **/*_bench.rs");
+    });
+
     it("groups patterns under the JS / TS sub-header", () => {
       const content = generateStarterIgnoreFile(testDir);
       expect(content).toContain("# JS / TS");
     });
 
-    it("emits language groups in stable order: JS, C#, Java, Go, C++, Python", () => {
+    it("emits language groups in stable order: JS, C#, Java, Go, C++, Python, Rust", () => {
       const content = generateStarterIgnoreFile(testDir);
       const jsIdx = content.indexOf("# JS / TS");
       const csIdx = content.indexOf("# C# / .NET");
       const javaIdx = content.indexOf("# Java / Kotlin");
       const goIdx = content.indexOf("# Go");
       const cppIdx = content.indexOf("# C++");
       const pyIdx = content.indexOf("# Python");
+      const rustIdx = content.indexOf("# Rust");
       expect(jsIdx).toBeGreaterThan(-1);
       expect(csIdx).toBeGreaterThan(jsIdx);
       expect(javaIdx).toBeGreaterThan(csIdx);
       expect(goIdx).toBeGreaterThan(javaIdx);
       expect(cppIdx).toBeGreaterThan(goIdx);
       expect(pyIdx).toBeGreaterThan(cppIdx);
+      expect(rustIdx).toBeGreaterThan(pyIdx);
     });
 
     it("keeps all suggestions commented even with no detected dirs and no .gitignore", () => {

understand-anything-plugin/packages/core/src/ignore-generator.ts

@@ -34,6 +34,7 @@ const EXACT_DIR_NAMES = [
   "bench",
   "benchmark",
   "benchmarks",
+  "benches",
 ];
 
 // Directory-name suffixes matched case-insensitively via String.endsWith.
@@ -111,6 +112,27 @@ const TEST_PATTERN_GROUPS: Array<{ label: string; patterns: string[] }> = [
       "**/conftest.py",
     ],
   },
+  {
+    // Rust testing is bimodal, similar to Python. Library-scale crates
+    // (ripgrep, alacritty, helix, cargo) keep unit tests inline in
+    // `#[cfg(test)] mod tests { ... }` blocks that no file-pattern
+    // rule can catch, so the group barely moves the needle for them.
+    // Workspace monorepos (paritytech/polkadot-sdk, solana-labs/solana,
+    // rust-lang/rust) colocate a `foo_test.rs` beside `foo.rs` at
+    // scale — measurement showed *_test.rs alone accounts for the
+    // majority of hits (232 files / −15% on polkadot-sdk analysed
+    // budget). Integration tests already live under tests/ and Cargo
+    // benches under benches/ (both dir-covered), so the file globs
+    // here target the colocated shape specifically.
+    label: "Rust",
+    patterns: [
+      "**/tests.rs",
+      "**/test_*.rs",
+      "**/*_test.rs",
+      "**/bench_*.rs",
+      "**/*_bench.rs",
+    ],
+  },
 ];
 
 /**