diff --git a/src/confid/mod.rs b/src/confid/mod.rs
index 63dc290..077c2f5 100644
--- a/src/confid/mod.rs
+++ b/src/confid/mod.rs
@@ -4,7 +4,7 @@ use thiserror::Error;
 
 mod black_box;
 
-#[derive(Error, Debug)]
+#[derive(Error, Debug, PartialEq, Eq)]
 pub enum ConfirmationIdError {
     #[error("Installation ID is too short.")]
     TooShort,
@@ -47,3 +47,32 @@ pub fn generate(installation_id: &str) -> Result<String, ConfirmationIdError> {
             .to_string())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_generate() {
+        assert_eq!(
+            generate("334481558826870862843844566221823392794862457401103810").unwrap(),
+            "110281-200130-887120-647974-697175-027544-252733"
+        );
+        assert!(
+            generate("33448155882687086284384456622182339279486245740110381")
+                .is_err_and(|err| err == ConfirmationIdError::TooShort),
+        );
+        assert!(
+            generate("3344815588268708628438445662218233927948624574011038100")
+                .is_err_and(|err| err == ConfirmationIdError::TooLarge),
+        );
+        assert!(
+            generate("33448155882687086284384456622182339279486245740110381!")
+                .is_err_and(|err| err == ConfirmationIdError::InvalidCharacter),
+        );
+        assert!(
+            generate("334481558826870862843844566221823392794862457401103811")
+                .is_err_and(|err| err == ConfirmationIdError::InvalidCheckDigit),
+        );
+    }
+}