Forward serdevalid collection bounds through Nullable

src/nullable_format.rs

@@ -703,6 +703,26 @@ impl_generic_composited_validation_nullable!(MinProperties, usize);
 #[cfg(feature = "serdevalid")]
 impl_generic_composited_validation_nullable!(Enum<T>);
 
+#[cfg(feature = "serdevalid")]
+impl<T: serde_valid::ValidateMinItems> serde_valid::ValidateMinItems for Nullable<T> {
+    fn validate_min_items(&self, min_items: usize) -> Result<(), serde_valid::MinItemsError> {
+        match self {
+            Self::Null => Ok(()),
+            Self::Present(value) => value.validate_min_items(min_items),
+        }
+    }
+}
+
+#[cfg(feature = "serdevalid")]
+impl<T: serde_valid::ValidateMaxItems> serde_valid::ValidateMaxItems for Nullable<T> {
+    fn validate_max_items(&self, max_items: usize) -> Result<(), serde_valid::MaxItemsError> {
+        match self {
+            Self::Null => Ok(()),
+            Self::Present(value) => value.validate_max_items(max_items),
+        }
+    }
+}
+
 /// Serde helper function to create a default `Option<Nullable<T>>` while
 /// deserializing
 pub fn default_optional_nullable<T>() -> Option<Nullable<T>> {

tests/nullable_collection_validation.rs

@@ -0,0 +1,52 @@
+#![cfg(feature = "serdevalid")]
+
+use serde_valid::Validate;
+use swagger::Nullable;
+
+#[derive(Validate)]
+struct Collection {
+    #[validate(min_items = 1)]
+    #[validate(max_items = 2)]
+    values: Nullable<Vec<String>>,
+}
+
+#[derive(Validate)]
+struct OptionalCollection {
+    #[validate(min_items = 1)]
+    #[validate(max_items = 2)]
+    values: Option<Nullable<Vec<String>>>,
+}
+
+#[test]
+fn nullable_collection_bounds_apply_to_present_values() {
+    assert!(Collection {
+        values: Nullable::Null
+    }
+    .validate()
+    .is_ok());
+    assert!(OptionalCollection { values: None }.validate().is_ok());
+    assert!(OptionalCollection {
+        values: Some(Nullable::Null)
+    }
+    .validate()
+    .is_ok());
+    for size in 0..=3 {
+        let values = vec![String::new(); size];
+        assert_eq!(
+            Collection {
+                values: Nullable::Present(values.clone())
+            }
+            .validate()
+            .is_ok(),
+            (1..=2).contains(&size)
+        );
+        assert_eq!(
+            OptionalCollection {
+                values: Some(Nullable::Present(values))
+            }
+            .validate()
+            .is_ok(),
+            (1..=2).contains(&size)
+        );
+    }
+}