Tests for ratelimiter config strings

Signed-off-by: Olivier 'reivilibre <olivier@librepush.net>

src/config.rs

@@ -184,6 +184,7 @@ pub struct RatelimitsConfig {
 /// - "5 Hz, 20 burst"
 /// - "5 per second, 10 burst"
 /// - "10 per hour, 5 burst"
+#[derive(Debug)]
 pub struct RatelimiterConfig {
     /// The inner [`Quota`], which this struct is just a wrapper for.
     pub quota: Quota,
@@ -196,13 +197,19 @@ impl<'de> Deserialize<'de> for RatelimiterConfig {
     {
         let stringy_format = String::deserialize(deserializer)?;
         let Some((left, right)) = stringy_format.split_once(',') else {
-            return Err(D::Error::custom("no comma. ratelimiter string should be like '5 Hz, 20 burst'"));
+            return Err(D::Error::custom(
+                "no comma. ratelimiter string should be like '5 Hz, 20 burst'",
+            ));
         };
         let Some((left_val, left_unit)) = left.trim().split_once(' ') else {
-            return Err(D::Error::custom("no units on left. ratelimiter string should be like '5 Hz, 20 burst'"));
+            return Err(D::Error::custom(
+                "no units on left. ratelimiter string should be like '5 Hz, 20 burst'",
+            ));
         };
         let Some((right_val, right_unit)) = right.trim().split_once(' ') else {
-            return Err(D::Error::custom("no units on right. ratelimiter string should be like '5 Hz, 20 burst'"));
+            return Err(D::Error::custom(
+                "no units on right. ratelimiter string should be like '5 Hz, 20 burst'",
+            ));
         };
 
         let Ok(left_val) = left_val.parse::<NonZeroU32>() else {
@@ -237,3 +244,62 @@ impl<'de> Deserialize<'de> for RatelimiterConfig {
         Ok(RatelimiterConfig { quota })
     }
 }
+
+#[cfg(test)]
+mod test {
+    use crate::config::RatelimiterConfig;
+
+    #[test]
+    fn test_ratelimiter_deser_errors() {
+        fn deser(s: &str) -> Result<RatelimiterConfig, serde_json::Error> {
+            serde_json::from_value(serde_json::Value::String(s.to_owned()))
+        }
+
+        // this is fine
+        deser("5 Hz, 20 burst").unwrap();
+
+        // no comma
+        assert_eq!(
+            deser("5 Hz 20 burst").unwrap_err().to_string(),
+            "no comma. ratelimiter string should be like '5 Hz, 20 burst'"
+        );
+
+        // bad numbers
+        assert_eq!(
+            deser("five Hz, 20 burst").unwrap_err().to_string(),
+            "bad value on left. ratelimiter string should be like '5 Hz, 20 burst'"
+        );
+        assert_eq!(
+            deser("5 Hz, twenty burst").unwrap_err().to_string(),
+            "bad value on right. ratelimiter string should be like '5 Hz, 20 burst'"
+        );
+
+        // wrong order
+        assert_eq!(
+            deser("20 burst, 5 Hz").unwrap_err().to_string(),
+            "bad units on left. ratelimiter string should be like '5 Hz, 20 burst' or '5 per hour, 20 burst'."
+        );
+
+        // no units
+        assert_eq!(
+            deser("5 Hz, 20").unwrap_err().to_string(),
+            "no units on right. ratelimiter string should be like '5 Hz, 20 burst'"
+        );
+        assert_eq!(
+            deser("5, 20 burst").unwrap_err().to_string(),
+            "no units on left. ratelimiter string should be like '5 Hz, 20 burst'"
+        );
+
+        // bad units
+        assert_eq!(
+            deser("20 per milleniumm, 20 burst")
+                .unwrap_err()
+                .to_string(),
+            "bad units on left. ratelimiter string should be like '5 Hz, 20 burst' or '5 per hour, 20 burst'."
+        );
+        assert_eq!(
+            deser("5 Hz, 20 wombats").unwrap_err().to_string(),
+            "bad units on right. ratelimiter string should be like '5 Hz, 20 burst' or '5 per hour, 20 burst'."
+        );
+    }
+}