diff --git a/Cargo.lock b/Cargo.lock
index 77aeba0..49d41d4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -507,6 +507,41 @@ dependencies = [
  "typenum",
 ]
 
+[[package]]
+name = "darling"
+version = "0.20.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc7f46116c46ff9ab3eb1597a45688b6715c6e628b5c133e288e709a29bcb4ee"
+dependencies = [
+ "darling_core",
+ "darling_macro",
+]
+
+[[package]]
+name = "darling_core"
+version = "0.20.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d00b9596d185e565c2207a0b01f8bd1a135483d02d9b7b0a54b11da8d53412e"
+dependencies = [
+ "fnv",
+ "ident_case",
+ "proc-macro2",
+ "quote",
+ "strsim",
+ "syn",
+]
+
+[[package]]
+name = "darling_macro"
+version = "0.20.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc34b93ccb385b40dc71c6fceac4b2ad23662c7eeb248cf10d529b7e055b6ead"
+dependencies = [
+ "darling_core",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "der"
 version = "0.7.10"
@@ -1038,6 +1073,12 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "ident_case"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
+
 [[package]]
 name = "idna"
 version = "1.1.0"
@@ -1548,6 +1589,28 @@ dependencies = [
  "zerocopy",
 ]
 
+[[package]]
+name = "proc-macro-error-attr2"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96de42df36bb9bba5542fe9f1a054b8cc87e172759a1868aa05c1f3acc89dfc5"
+dependencies = [
+ "proc-macro2",
+ "quote",
+]
+
+[[package]]
+name = "proc-macro-error2"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "11ec05c52be0a07b08061f7dd003e7d7092e0472bc731b4af7bb1ef876109802"
+dependencies = [
+ "proc-macro-error-attr2",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.101"
@@ -2154,6 +2217,12 @@ dependencies = [
  "unicode-properties",
 ]
 
+[[package]]
+name = "strsim"
+version = "0.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
+
 [[package]]
 name = "subtle"
 version = "2.6.1"
@@ -2544,6 +2613,21 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "url",
+ "validator_derive",
+]
+
+[[package]]
+name = "validator_derive"
+version = "0.20.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7df16e474ef958526d1205f6dda359fdfab79d9aa6d54bafcb92dcd07673dca"
+dependencies = [
+ "darling",
+ "once_cell",
+ "proc-macro-error2",
+ "proc-macro2",
+ "quote",
+ "syn",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 128758f..78c7536 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -49,7 +49,7 @@ sqlx = { version = "0.8", optional = true, default-features = false, features =
   "migrate",
 ] }
 redis = { version = "0.32", optional = true, default-features = false }
-validator = { version = "0.20", optional = true }
+validator = { version = "0.20", optional = true, features = ["derive"] }
 config = { version = "0.15", optional = true }
 utoipa = { version = "5.3", optional = true }
 tokio = { version = "1", optional = true, features = ["time"] }
diff --git a/src/convert/sqlx.rs b/src/convert/sqlx.rs
index 4bdf0e4..f79e9c2 100644
--- a/src/convert/sqlx.rs
+++ b/src/convert/sqlx.rs
@@ -61,3 +61,24 @@ impl From<MigrateError> for AppError {
         AppError::database(Some(err.to_string()))
     }
 }
+
+#[cfg(all(test, feature = "sqlx"))]
+mod tests {
+    use std::io;
+
+    use super::*;
+    use crate::AppErrorKind;
+
+    #[test]
+    fn row_not_found_maps_to_not_found() {
+        let err: AppError = SqlxError::RowNotFound.into();
+        assert!(matches!(err.kind, AppErrorKind::NotFound));
+    }
+
+    #[test]
+    fn other_error_maps_to_database() {
+        let io_err = io::Error::new(io::ErrorKind::Other, "boom");
+        let err: AppError = SqlxError::Io(io_err).into();
+        assert!(matches!(err.kind, AppErrorKind::Database));
+    }
+}
diff --git a/src/convert/tokio.rs b/src/convert/tokio.rs
index a5199c7..8592095 100644
--- a/src/convert/tokio.rs
+++ b/src/convert/tokio.rs
@@ -49,3 +49,21 @@ impl From<Elapsed> for AppError {
         AppError::timeout("Operation timed out")
     }
 }
+
+#[cfg(all(test, feature = "tokio"))]
+mod tests {
+    use tokio::time::{Duration, sleep, timeout};
+
+    use super::*;
+    use crate::AppErrorKind;
+
+    #[tokio::test]
+    async fn elapsed_maps_to_timeout() {
+        let fut = sleep(Duration::from_millis(20));
+        let err = timeout(Duration::from_millis(1), fut)
+            .await
+            .expect_err("expect timeout");
+        let app_err: AppError = err.into();
+        assert!(matches!(app_err.kind, AppErrorKind::Timeout));
+    }
+}
diff --git a/src/convert/validator.rs b/src/convert/validator.rs
index a25091b..0022f0e 100644
--- a/src/convert/validator.rs
+++ b/src/convert/validator.rs
@@ -56,3 +56,26 @@ impl From<ValidationErrors> for AppError {
         AppError::validation(err.to_string())
     }
 }
+
+#[cfg(all(test, feature = "validator"))]
+mod tests {
+    use validator::Validate;
+
+    use super::*;
+    use crate::AppErrorKind;
+
+    #[derive(Validate)]
+    struct Payload {
+        #[validate(range(min = 1))]
+        val: i32
+    }
+
+    #[test]
+    fn validation_errors_map_to_validation_kind() {
+        let bad = Payload {
+            val: 0
+        };
+        let err: AppError = bad.validate().unwrap_err().into();
+        assert!(matches!(err.kind, AppErrorKind::Validation));
+    }
+}