Fix unicode encoding of hyperlinks

The problem, is I based the code on the implementation in ripgrep. But
while ripgrep is writing directly to the stream, I am using a Formatter,
which means I have to write characters, not raw bytes.

Thus we need to percent encode all non-ascii bytes (or we could switch
to writing bytes directly, but that would be more complicated, and I
think percent encoding is safer anyway).

src/hyperlink.rs

@@ -26,17 +26,16 @@ impl fmt::Display for PathUrl {
 }
 
 fn encode(f: &mut Formatter, byte: u8) -> fmt::Result {
+    // NOTE:
+    // Most terminals can handle non-ascii unicode characters in a file url fine. But on some OSes (notably
+    // windows), the encoded bytes of the path may not be valid UTF-8. Since we don't know if a
+    // byte >= 128 is part of a valid UTF-8 encoding or not, we just percent encode any non-ascii
+    // byte.
+    // Percent encoding these bytes is probably safer anyway.
     match byte {
-        b'0'..=b'9'
+        b'0'..=b'9' | b'A'..=b'Z' | b'a'..=b'z' | b'/' | b':' | b'-' | b'.' | b'_' | b'~' => {
-        | b'A'..=b'Z'
+            f.write_char(byte.into())
-        | b'a'..=b'z'
+        }
-        | b'/'
-        | b':'
-        | b'-'
-        | b'.'
-        | b'_'
-        | b'~'
-        | 128.. => f.write_char(byte.into()),
         #[cfg(windows)]
         b'\\' => f.write_char('/'),
         _ => {
@@ -61,3 +60,21 @@ fn host() -> &'static str {
 const fn host() -> &'static str {
     ""
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_unicode_encoding() {
+        let path: PathBuf = "/$*\x1bßé/∫😃".into();
+        let url = PathUrl::new(&path).unwrap();
+        assert_eq!(
+            url.to_string(),
+            format!(
+                "file://{}/%24%2A%1B%C3%9F%C3%A9/%E2%88%AB%F0%9F%98%83",
+                host()
+            ),
+        );
+    }
+}