From 6fedc57848da2735b89a777574211472d0ba9366 Mon Sep 17 00:00:00 2001
From: Zachary Pierce <zack@auxon.io>
Date: Fri, 9 Aug 2019 15:55:33 -0700
Subject: [PATCH] Add generative test cases

---
 Cargo.toml   |  3 +++
 tests/lib.rs | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/Cargo.toml b/Cargo.toml
index df18a09..64e7a0b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,3 +16,6 @@ exclude = ["/.travis.yml", "/dev"]
 
 [badges]
 travis-ci = { repository = "dguo/strsim-rs" }
+
+[dev-dependencies]
+proptest = "0.9.4"
diff --git a/tests/lib.rs b/tests/lib.rs
index ad7af51..9553756 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -1,4 +1,6 @@
 extern crate strsim;
+extern crate proptest;
+use proptest::prelude::*;
 
 use strsim::{hamming, levenshtein, normalized_levenshtein, osa_distance,damerau_levenshtein,
              normalized_damerau_levenshtein, jaro, jaro_winkler};
@@ -47,3 +49,64 @@ fn jaro_winkler_works() {
     assert!((0.911 - jaro_winkler("cheeseburger", "cheese fries")).abs() <
             0.001);
 }
+
+proptest! {
+    #[test]
+    fn hamming_arbitrary_strings_work(a in ".*", b in ".*") {
+        match hamming(a.as_str(), b.as_str()) {
+            Ok(v) => {
+                assert!(v <= a.len().max(b.len()));
+            },
+            Err(_) => {
+                assert_ne!(a.chars().count(), b.chars().count());
+            }
+        }
+    }
+    #[test]
+    fn jaro_arbitrary_strings_work(a in ".*", b in ".*") {
+        let v = jaro(a.as_str(), b.as_str());
+        assert!(v >= 0.0 && v <= 1.0);
+        if v == 1.0 {
+            assert_eq!(a, b);
+        }
+    }
+    #[test]
+    fn jaro_winkler_arbitrary_strings_work(a in ".*", b in ".*") {
+        let v = jaro_winkler(a.as_str(), b.as_str());
+        assert!(v >= 0.0 && v <= 1.0);
+        if v == 1.0 {
+            assert_eq!(a, b);
+        }
+    }
+    #[test]
+    fn levenshtein_arbitrary_strings_work(a in ".*", b in ".*") {
+        let v = levenshtein(a.as_str(), b.as_str());
+        assert!(v <= a.chars().count().max(b.chars().count()));
+    }
+    #[test]
+    fn normalized_levenshtein_arbitrary_strings_work(a in ".*", b in ".*") {
+        let v = normalized_levenshtein(a.as_str(), b.as_str());
+        assert!(v >= 0.0 && v <= 1.0);
+        if v == 1.0 {
+            assert_eq!(a, b);
+        }
+    }
+    #[test]
+    fn osa_distance_arbitrary_strings_work(a in ".*", b in ".*") {
+        let v = osa_distance(a.as_str(), b.as_str());
+        assert!(v <= a.chars().count().max(b.chars().count()));
+    }
+    #[test]
+    fn damerau_levenshtein_arbitrary_strings_work(a in ".*", b in ".*") {
+        let v = damerau_levenshtein(a.as_str(), b.as_str());
+        assert!(v <= a.chars().count().max(b.chars().count()));
+    }
+    #[test]
+    fn normalized_damerau_levenshtein_arbitrary_strings_work(a in ".*", b in ".*") {
+        let v = normalized_damerau_levenshtein(a.as_str(), b.as_str());
+        assert!(v >= 0.0 && v <= 1.0);
+        if v == 1.0 {
+            assert_eq!(a, b);
+        }
+    }
+}