diff --git a/src/core/auth.rs b/src/core/auth.rs
index f041c8f2..783faa0d 100644
--- a/src/core/auth.rs
+++ b/src/core/auth.rs
@@ -146,11 +146,11 @@ impl Key {
     /// Valid keys can only contain 32 chars including 0-9, a-z and A-Z.
     pub fn new(value: &str) -> Result<Self, ParseKeyError> {
         if value.len() != AUTH_KEY_LENGTH {
-            return Err(ParseKeyError);
+            return Err(ParseKeyError::InvalidKeyLength);
         }
 
         if !value.chars().all(|c| c.is_ascii_alphanumeric()) {
-            return Err(ParseKeyError);
+            return Err(ParseKeyError::InvalidChars);
         }
 
         Ok(Self(value.to_owned()))
@@ -175,9 +175,15 @@ impl Key {
 /// assert_eq!(key.unwrap().to_string(), key_string);
 /// ```
 ///
-/// If the string does not contains a valid key, the parser function will return this error.
-#[derive(Debug, PartialEq, Eq, Display)]
-pub struct ParseKeyError;
+/// If the string does not contains a valid key, the parser function will return
+/// this error.
+#[derive(Debug, Error)]
+pub enum ParseKeyError {
+    #[error("Invalid key length. Key must be have 32 chars")]
+    InvalidKeyLength,
+    #[error("Invalid chars for key. Key can only alphanumeric chars (0-9, a-z, A-Z)")]
+    InvalidChars,
+}
 
 impl FromStr for Key {
     type Err = ParseKeyError;
@@ -188,8 +194,8 @@ impl FromStr for Key {
     }
 }
 
-/// Verification error. Error returned when an [`ExpiringKey`] cannot be verified with the [`verify(...)`](crate::core::auth::verify) function.
-///
+/// Verification error. Error returned when an [`ExpiringKey`] cannot be
+/// verified with the [`verify(...)`](crate::core::auth::verify) function.
 #[derive(Debug, Error)]
 #[allow(dead_code)]
 pub enum Error {
diff --git a/tests/servers/api/v1/asserts.rs b/tests/servers/api/v1/asserts.rs
index ba906f65..aeecfa17 100644
--- a/tests/servers/api/v1/asserts.rs
+++ b/tests/servers/api/v1/asserts.rs
@@ -61,6 +61,12 @@ pub async fn assert_bad_request(response: Response, body: &str) {
     assert_eq!(response.text().await.unwrap(), body);
 }
 
+pub async fn assert_bad_request_with_text(response: Response, text: &str) {
+    assert_eq!(response.status(), 400);
+    assert_eq!(response.headers().get("content-type").unwrap(), "text/plain; charset=utf-8");
+    assert!(response.text().await.unwrap().contains(text));
+}
+
 pub async fn assert_unprocessable_content(response: Response, text: &str) {
     assert_eq!(response.status(), 422);
     assert_eq!(response.headers().get("content-type").unwrap(), "text/plain; charset=utf-8");
@@ -93,20 +99,9 @@ pub async fn assert_invalid_auth_key_get_param(response: Response, invalid_auth_
 }
 
 pub async fn assert_invalid_auth_key_post_param(response: Response, invalid_auth_key: &str) {
-    assert_bad_request(
+    assert_bad_request_with_text(
         response,
-        &format!(
-            "Invalid URL: invalid auth key: string \"{}\", ParseKeyError",
-            &invalid_auth_key
-        ),
-    )
-    .await;
-}
-
-pub async fn _assert_unprocessable_auth_key_param(response: Response, _invalid_value: &str) {
-    assert_unprocessable_content(
-        response,
-        "Failed to deserialize the JSON body into the target type: seconds_valid: invalid type",
+        &format!("Invalid URL: invalid auth key: string \"{}\"", &invalid_auth_key),
     )
     .await;
 }