chore: checkpoint before Python removal

vendor/ecdsa/tests/lib.rs

@@ -0,0 +1,14 @@
+//! Smoke tests which use `MockCurve`
+
+#![cfg(feature = "dev")]
+
+use elliptic_curve::dev::MockCurve;
+
+type Signature = ecdsa::Signature<MockCurve>;
+type SignatureBytes = ecdsa::SignatureBytes<MockCurve>;
+
+#[test]
+fn rejects_all_zero_signature() {
+    let all_zero_bytes = SignatureBytes::default();
+    assert!(Signature::try_from(all_zero_bytes.as_ref()).is_err());
+}