feat(checkers): add avoid_expect built-in rule for Rust

checkers/rust/avoid_expect.test.rs

@@ -0,0 +1,27 @@
+fn test_antipattern() {
+    let some_option: Option<i32> = None;
+
+    // <expect-error>
+    let _ = some_option.expect("failed to get value");
+
+    let some_result: Result<i32, &str> = Err("Error occurred");
+
+    // <expect-error>
+    let _ = some_result.expect("failed to process result");
+}
+
+fn test_safe() {
+    let some_option: Option<i32> = None;
+
+    // Safe error handling with unwrap_or
+    let _ = some_option.unwrap_or(42);
+
+    // Safe error handling with match
+    let _ = match some_option {
+        Some(val) => val,
+        None => 0,
+    };
+
+    // Should not flag string literals containing "expect"
+    let message = "We expect proper error handling in production code.";
+}

checkers/rust/avoid_expect.yml

@@ -0,0 +1,29 @@
+language: rust
+name: avoid_expect
+message: "Using expect() can cause runtime panics if an Option is None or Result is Err. Consider handling errors explicitly with match, if let, or the ? operator"
+category: antipattern
+severity: warning
+
+pattern: |
+  (
+    (call_expression
+      function: (field_expression
+        value: (_) @variable
+        field: (field_identifier) @method_name
+        (#eq? @method_name "expect")
+      )
+      arguments: (arguments)
+    ) @avoid_expect
+  )
+
+exclude:
+  - "tests/**"
+  - "vendor/**"
+  - "**/test_*.rs"
+  - "**/*_test.rs"
+
+description: |
+  Using .expect() in Rust can lead to unexpected panics if the value is None (for Option) or Err (for Result).
+  While expect() provides a custom error message, uncaught panics in production can crash the application.
+  Consider handling errors explicitly using match or if let, providing defaults with unwrap_or_else(),
+  or propagating errors using the ? operator.