rust: Add some unit tests for parse_byte_size in config

Differential Revision: https://phab.mercurial-scm.org/D10022

rust/hg-core/src/config/values.rs

@@ -1,43 +1,61 b''
 //! Parsing functions for various type of configuration values.
 //!
 //! Returning `None` indicates a syntax error. Using a `Result` would be more
 //! correct but would take more boilerplate for converting between error types,
 //! compared to using `.ok()` on inner results of various error types to
 //! convert them all to options. The `Config::get_parse` method later converts
 //! those options to results with `ConfigValueParseError`, which contains
 //! details about where the value came from (but omits details of what’s
 //! invalid inside the value).
 
 pub(super) fn parse_bool(v: &[u8]) -> Option<bool> {
     match v.to_ascii_lowercase().as_slice() {
         b"1" | b"yes" | b"true" | b"on" | b"always" => Some(true),
         b"0" | b"no" | b"false" | b"off" | b"never" => Some(false),
         _ => None,
     }
 }
 
 pub(super) fn parse_byte_size(value: &[u8]) -> Option<u64> {
     let value = std::str::from_utf8(value).ok()?.to_ascii_lowercase();
     const UNITS: &[(&str, u64)] = &[
         ("g", 1 << 30),
         ("gb", 1 << 30),
         ("m", 1 << 20),
         ("mb", 1 << 20),
         ("k", 1 << 10),
         ("kb", 1 << 10),
         ("b", 1 << 0), // Needs to be last
     ];
     for &(unit, multiplier) in UNITS {
         // TODO: use `value.strip_suffix(unit)` when we require Rust 1.45+
         if value.ends_with(unit) {
             let value_before_unit = &value[..value.len() - unit.len()];
             let float: f64 = value_before_unit.trim().parse().ok()?;
             if float >= 0.0 {
                 return Some((float * multiplier as f64).round() as u64);
             } else {
                 return None;
             }
         }
     }
     value.parse().ok()
 }
+
+#[test]
+fn test_parse_byte_size() {
+    assert_eq!(parse_byte_size(b""), None);
+    assert_eq!(parse_byte_size(b"b"), None);
+
+    assert_eq!(parse_byte_size(b"12"), Some(12));
+    assert_eq!(parse_byte_size(b"12b"), Some(12));
+    assert_eq!(parse_byte_size(b"12 b"), Some(12));
+    assert_eq!(parse_byte_size(b"12.1 b"), Some(12));
+    assert_eq!(parse_byte_size(b"1.1 K"), Some(1126));
+    assert_eq!(parse_byte_size(b"1.1 kB"), Some(1126));
+
+    assert_eq!(parse_byte_size(b"-12 b"), None);
+    assert_eq!(parse_byte_size(b"-0.1 b"), None);
+    assert_eq!(parse_byte_size(b"0.1 b"), Some(0));
+    assert_eq!(parse_byte_size(b"12.1 b"), Some(12));
+}