feat(confik): add js_option crate support

confik/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Implement `Configuration` for [`js_option::JsOption`](https://docs.rs/js_option/0.1.1/js_option/enum.JsOption.html)
+
 ## 0.13.0
 
 - Update `bytesize` dependency to `2`.

confik/Cargo.toml

@@ -35,6 +35,7 @@ camino = ["dep:camino"]
 chrono = ["dep:chrono"]
 common = []
 ipnetwork = ["dep:ipnetwork"]
+js_option = ["dep:js_option"]
 rust_decimal = ["dep:rust_decimal"]
 secrecy = ["dep:secrecy"]
 url = ["dep:url"]
@@ -56,6 +57,7 @@ bytesize = { version = "2", optional = true, features = ["serde"] }
 camino = { version = "1", optional = true, features = ["serde1"] }
 chrono = { version = "0.4.40", optional = true, default-features = false, features = ["serde"] }
 ipnetwork = { version = "0.21", optional = true, features = ["serde"] }
+js_option = { version = "0.1", optional = true, features = ["serde"] }
 rust_decimal = { version = "1", optional = true, features = ["serde"] }
 secrecy = { version = "0.10", optional = true, features = ["serde"] }
 url = { version = "2", optional = true, features = ["serde"] }

confik/src/third_party.rs

@@ -119,6 +119,62 @@ mod ipnetwork {
     }
 }
 
+#[cfg(feature = "js_option")]
+mod js_option {
+    use js_option::JsOption;
+    use serde::de::DeserializeOwned;
+
+    use crate::{Configuration, ConfigurationBuilder};
+
+    impl<T> Configuration for JsOption<T>
+    where
+        T: DeserializeOwned + Configuration,
+    {
+        type Builder = JsOption<<T as Configuration>::Builder>;
+    }
+
+    impl<T> ConfigurationBuilder for JsOption<T>
+    where
+        T: DeserializeOwned + ConfigurationBuilder,
+    {
+        type Target = JsOption<<T as ConfigurationBuilder>::Target>;
+
+        fn merge(self, other: Self) -> Self {
+            match (self, other) {
+                // If both `Some` then merge the contained builders
+                (Self::Some(us), Self::Some(other)) => Self::Some(us.merge(other)),
+                // If we don't have a value then always take the other
+                (Self::Undefined, other) => other,
+                // Either:
+                // - We're explicitly `Null`
+                // - We're explicitly `Some` and the other is `Undefined` or `Null`
+                //
+                // In either case, just take our value, which should be preferred to other.
+                (us, _) => us,
+            }
+        }
+
+        fn try_build(self) -> Result<Self::Target, crate::Error> {
+            match self {
+                Self::Undefined => Ok(Self::Target::Undefined),
+                Self::Null => Ok(Self::Target::Null),
+                Self::Some(val) => Ok(Self::Target::Some(val.try_build()?)),
+            }
+        }
+
+        fn contains_non_secret_data(&self) -> Result<bool, crate::UnexpectedSecret> {
+            match self {
+                Self::Some(data) => data.contains_non_secret_data(),
+
+                // An explicit `Null` is counted as data, overriding any default.
+                Self::Null => Ok(true),
+
+                Self::Undefined => Ok(false),
+            }
+        }
+    }
+}
+
 #[cfg(feature = "secrecy")]
 mod secrecy {
     use secrecy::SecretString;

confik/tests/third_party.rs

@@ -126,3 +126,76 @@ mod bigdecimal {
         }
     }
 }
+
+#[cfg(feature = "js_option")]
+mod js_option {
+    use confik::{Configuration, TomlSource};
+    use js_option::JsOption;
+
+    #[derive(Configuration, Debug)]
+    struct Config {
+        opt: JsOption<usize>,
+    }
+
+    #[test]
+    fn undefined() {
+        let config = Config::builder()
+            .try_build()
+            .expect("Should be valid without config");
+        assert_eq!(config.opt, JsOption::Undefined);
+    }
+
+    #[cfg(feature = "json")]
+    #[test]
+    fn null() {
+        let json = r#"{ "opt": null }"#;
+
+        let config = Config::builder()
+            .override_with(confik::JsonSource::new(json))
+            .try_build()
+            .expect("Failed to parse config");
+        assert_eq!(config.opt, JsOption::Null);
+    }
+
+    #[test]
+    fn present() {
+        let toml = "opt = 5";
+
+        let config = Config::builder()
+            .override_with(TomlSource::new(toml))
+            .try_build()
+            .expect("Should be valid without config");
+        assert_eq!(config.opt, JsOption::Some(5));
+    }
+
+    #[cfg(feature = "json")]
+    #[test]
+    fn merge() {
+        #[derive(Debug, Configuration, PartialEq, Eq)]
+        struct Config {
+            one: JsOption<usize>,
+            two: JsOption<usize>,
+            three: JsOption<usize>,
+            four: JsOption<usize>,
+        }
+
+        let base = r#"{ "two": null, "three": 5 }"#;
+        let merge = r#"{ "one": 1, "two": 2, "three": 3}"#;
+
+        let config = Config::builder()
+            .override_with(confik::JsonSource::new(merge))
+            .override_with(confik::JsonSource::new(base))
+            .try_build()
+            .expect("Failed to parse config");
+
+        assert_eq!(
+            config,
+            Config {
+                one: JsOption::Some(1),
+                two: JsOption::Null,
+                three: JsOption::Some(5),
+                four: JsOption::Undefined,
+            }
+        );
+    }
+}