diff --git a/src/crypto.rs b/src/crypto.rs
index 2f13194..67dae6b 100644
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -154,3 +154,90 @@ pub fn is_encrypted(body: &Bytes) -> bool {
     }
     false
 }
+
+#[cfg(test)]
+pub mod tests {
+   use bytes::Bytes;
+
+#[test]
+    pub fn test_is_encrypted() {
+
+        use crate::crypto::is_encrypted;
+
+        // cleartext
+        let body = b"Hello world";
+        let body = Bytes::from(&body[..]);
+        assert!(! is_encrypted(&body));
+
+        // a valid encrypted message
+        let body = b"-----BEGIN PGP MESSAGE-----
+
+wWwGFQRhclhA/Qg3CiL81NAswyOWkyk8jxIBB0AmlBkVEVbQst60C/1+mcmIxLbG
+m0w+qv2aP5NQhAetCzDgA/KEhtim0Ebzf06jJG7bITPkYmfN2mizdChgv1f3y2eQ
+80hYpgbD930RtKXTD1TSWgIJAgai2MelZrDAQXIaFKlRRY9u7R1YIXQmMa6uDced
+W/g9mJDd0ral30VL0FfuKRR2Je2TRfizqMb4tL4EIRFqrfSBesb9WcniEfBekG3B
+jk6lh01Ej9QTGQ==
+-----END PGP MESSAGE-----
+";
+
+        let body = Bytes::from(&body[..]);
+        assert!(is_encrypted(&body));
+
+        // a PUBLIC KEY BLOCK is an artifact, but it's not encrypted
+        let body = b"-----BEGIN PGP PUBLIC KEY BLOCK-----
+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+=WPEh
+-----END PGP PUBLIC KEY BLOCK-----
+";
+        let body = Bytes::from(&body[..]);
+        assert!(! is_encrypted(&body));
+
+        // broken message
+        let body = b"-----BEGIN PGP MESSAGE-----
+
+wWwGFQRhclhA/Qg3CiL81NAswyOWkyk8jxIBB0AmlBkVEVbQst60C/1+mcmIxLbG
+W/g9mJDd0ral30VL0FfuKRR2Je2TRfizqMb4tL4EIRFqrfSBesb9WcniEfBekG3B
+jk6lh01Ej9QTGQ==
+-----END PGP MESSAGE-----
+";
+        let body = Bytes::from(&body[..]);
+        assert!(! is_encrypted(&body));
+
+    }
+
+}