monero: match monero's stricter check when decompressing points (#515)

* monero: match monero's stricter check when decompressing points

* Reverted type change for output key

coins/monero/generators/src/tests/hash_to_point.rs

@@ -0,0 +1,38 @@
+use crate::{decompress_point, hash_to_point};
+
+#[test]
+fn crypto_tests() {
+  // tests.txt file copied from monero repo
+  // https://github.com/monero-project/monero/
+  //   blob/ac02af92867590ca80b2779a7bbeafa99ff94dcb/tests/crypto/tests.txt
+  let reader = include_str!("./tests.txt");
+
+  for line in reader.lines() {
+    let mut words = line.split_whitespace();
+    let command = words.next().unwrap();
+
+    match command {
+      "check_key" => {
+        let key = words.next().unwrap();
+        let expected = match words.next().unwrap() {
+          "true" => true,
+          "false" => false,
+          _ => unreachable!("invalid result"),
+        };
+
+        let actual = decompress_point(hex::decode(key).unwrap().try_into().unwrap());
+
+        assert_eq!(actual.is_some(), expected);
+      }
+      "hash_to_ec" => {
+        let bytes = words.next().unwrap();
+        let expected = words.next().unwrap();
+
+        let actual = hash_to_point(hex::decode(bytes).unwrap().try_into().unwrap());
+
+        assert_eq!(hex::encode(actual.compress().to_bytes()), expected);
+      }
+      _ => unreachable!("unknown command"),
+    }
+  }
+}