From c248016ea7ebc20551913cc1dfb5dc022fa3440d Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Sat, 17 Apr 2021 02:02:18 -0400
Subject: choose characters from alphabet with replacement for pwgen

---
 src/pwgen.rs | 44 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/pwgen.rs b/src/pwgen.rs
index dc6808f..cf63bb2 100644
--- a/src/pwgen.rs
+++ b/src/pwgen.rs
@@ -56,8 +56,50 @@ pub fn pwgen(ty: Type, len: usize) -> String {
 
     let mut rng = rand::thread_rng();
     let mut pass = vec![];
-    pass.extend(alphabet.choose_multiple(&mut rng, len).copied());
+    pass.extend(
+        std::iter::repeat_with(|| alphabet.choose(&mut rng).unwrap())
+            .take(len),
+    );
     // unwrap is safe because the method of generating passwords guarantees
     // valid utf8
     String::from_utf8(pass).unwrap()
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_pwgen() {
+        let pw = pwgen(Type::AllChars, 50);
+        assert_eq!(pw.len(), 50);
+        // technically this could fail, but the chances are incredibly low
+        // (around 0.000009%)
+        assert_duplicates(&pw);
+
+        let pw = pwgen(Type::AllChars, 100);
+        assert_eq!(pw.len(), 100);
+        assert_duplicates(&pw);
+
+        let pw = pwgen(Type::NoSymbols, 100);
+        assert_eq!(pw.len(), 100);
+        assert_duplicates(&pw);
+
+        let pw = pwgen(Type::Numbers, 100);
+        assert_eq!(pw.len(), 100);
+        assert_duplicates(&pw);
+
+        let pw = pwgen(Type::NonConfusables, 100);
+        assert_eq!(pw.len(), 100);
+        assert_duplicates(&pw);
+    }
+
+    #[track_caller]
+    fn assert_duplicates(s: &str) {
+        let mut set = std::collections::HashSet::new();
+        for c in s.chars() {
+            set.insert(c);
+        }
+        assert!(set.len() < s.len())
+    }
+}
-- 
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