[Frontend-Rust] Add test for recursive and triat implementation

Signed-off-by: Arthur Chan <[email protected]>

Author: arthurscchan

src/test/data/source-code/rust/test-project-5/fuzzer.rs

@@ -0,0 +1,29 @@
+// Copyright 2025 Fuzz Introspector Authors
+//
+// Licensed 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.
+
+#![no_main]
+
+pub mod recursive;
+
+#[macro_use]
+extern crate libfuzzer_sys;
+
+use crate::recursive::RecursiveStruct;
+
+fuzz_target!(|data: &[u8]| {
+    let mut instance = RecursiveStruct::new();
+    if let Ok(s) = std::str::from_utf8(data) {
+        let _ = unsafe { instance.process(s) };
+    }
+});

src/test/data/source-code/rust/test-project-5/recursive.rs

@@ -0,0 +1,37 @@
+// Copyright 2025 Google LLC
+//
+// Licensed 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.
+//
+////////////////////////////////////////////////////////////////////////////////
+
+pub trait RecursiveTrait {
+    fn process(&mut self, input: &str) -> String;
+}
+
+pub struct RecursiveStruct;
+
+impl RecursiveStruct {
+    pub fn new() -> Self {
+        RecursiveStruct
+    }
+}
+
+impl RecursiveTrait for RecursiveStruct {
+    fn process(&mut self, input: &str) -> String {
+        if input.is_empty() {
+            String::new()
+        } else {
+            self.process(&input[1..])
+        }
+    }
+}

src/test/test_frontends_rust.py

@@ -58,3 +58,22 @@ def test_tree_sitter_rust_sample2():
     # Callsite check
     assert 'double_add' in functions_reached
     assert 'add' in functions_reached
+
+
+def test_tree_sitter_rust_sample5():
+    project = oss_fuzz.analyse_folder(
+        'rust',
+        'src/test/data/source-code/rust/test-project-5',
+        dump_output=False,
+    )
+
+    # Project check
+    harness = project.get_source_codes_with_harnesses()
+    assert len(harness) == 1
+
+    functions_reached = project.get_reachable_functions(harness[0].source_file, harness[0])
+
+    # Callsite check
+    assert '&str::is_empty' in functions_reached
+    assert 'RecursiveStruct::new' in functions_reached
+    assert 'RecursiveStruct::process' in functions_reached