fix(loader): update parse boolean to work with all accepted yaml values (#633)

Author: joshfried-aws

guard/src/rules/libyaml/loader.rs

@@ -87,9 +87,9 @@ impl Loader {
                 Ok(i) => MarkedValue::Int(i, location),
                 Err(_) => match val.parse::<f64>() {
                     Ok(f) => MarkedValue::Float(f, location),
-                    Err(_) => match val.parse::<bool>() {
-                        Ok(b) => MarkedValue::Bool(b, location),
-                        Err(_) => match val.to_lowercase().as_str() {
+                    Err(_) => match self.parse_bool(&val) {
+                        Some(b) => MarkedValue::Bool(b, location),
+                        None => match val.to_lowercase().as_str() {
                             "~" | "null" => MarkedValue::Null(location),
                             _ => MarkedValue::String(val, location),
                         },
@@ -100,6 +100,23 @@ impl Loader {
 
         self.stack.push(path_value);
     }
+    fn is_bool_true(&self, s: &str) -> bool {
+        matches!(s, "true" | "yes" | "on" | "y")
+    }
+
+    fn is_bool_false(&self, s: &str) -> bool {
+        matches!(s, "false" | "no" | "off" | "n")
+    }
+
+    fn parse_bool(&self, val: &str) -> Option<bool> {
+        if self.is_bool_true(val) {
+            Some(true)
+        } else if self.is_bool_false(val) {
+            Some(false)
+        } else {
+            None
+        }
+    }
 
     fn handle_sequence_end(&mut self) {
         let array_idx = self.last_container_index.pop().unwrap();

guard/src/rules/libyaml/loader_tests.rs

@@ -28,6 +28,48 @@ fn yaml_loader() -> Result<()> {
     Ok(())
 }
 
+#[rstest::rstest]
+#[case::standard_lowercase_true("true", true)]
+#[case::standard_capitalized_true("True", true)]
+#[case::standard_uppercase_true("TRUE", true)]
+#[case::yaml_yes_lowercase("yes", true)]
+#[case::yaml_yes_capitalized("Yes", true)]
+#[case::yaml_yes_uppercase("YES", true)]
+#[case::yaml_on_lowercase("on", true)]
+#[case::yaml_on_capitalized("On", true)]
+#[case::yaml_on_uppercase("ON", true)]
+#[case::yaml_y_lowercase("y", true)]
+#[case::yaml_y_uppercase("Y", true)]
+#[case::standard_lowercase_false("false", false)]
+#[case::standard_capitalized_false("False", false)]
+#[case::standard_uppercase_false("FALSE", false)]
+#[case::yaml_no_lowercase("no", false)]
+#[case::yaml_no_capitalized("No", false)]
+#[case::yaml_no_uppercase("NO", false)]
+#[case::yaml_off_lowercase("off", false)]
+#[case::yaml_off_capitalized("Off", false)]
+#[case::yaml_off_uppercase("OFF", false)]
+#[case::yaml_n_lowercase("n", false)]
+#[case::yaml_n_uppercase("N", false)]
+fn test_handle_bool_happy_path(#[case] arg: &str, #[case] expected: bool) -> Result<()> {
+    let docs = format!("check: {arg}");
+
+    let mut loader = Loader::new();
+    match loader.load(String::from(docs))? {
+        MarkedValue::Map(map, ..) => {
+            assert!(map.len() == 1);
+            let (.., result) = map.first().unwrap();
+
+            if let MarkedValue::Bool(result, ..) = *result {
+                assert_eq!(result, expected);
+            }
+        }
+        _ => unreachable!("this isn't possible"),
+    }
+
+    Ok(())
+}
+
 #[test]
 fn yaml_loader2() -> Result<()> {
     let docs = r###"