handle empty hash when decoding guard char, fixes #21

ullmark · Apr 19, 2021 · a6759b7 · a6759b7
1 parent 75641a4
commit a6759b7
Show file tree

Hide file tree

Showing 2 changed files with 15 additions and 4 deletions.
diff --git a/src/Hashids.net/Hashids.cs b/src/Hashids.net/Hashids.cs
@@ -388,17 +388,17 @@ private long[] GetNumbersFrom(string hash)
             if (string.IsNullOrWhiteSpace(hash))
                 return EmptyArray;
 
-
-            var result = new List<long>();
-            int i = 0;
-
             var hashArray = hash.Split(_guards, StringSplitOptions.RemoveEmptyEntries);
+            if (hashArray.Length == 0)
+                return EmptyArray;
 
+            var i = 0;
             if (hashArray.Length == 3 || hashArray.Length == 2)
             {
                 i = 1;
             }
 
+            var result = new List<long>();
             var hashBreakdown = hashArray[i];
             if (hashBreakdown[0] != default(char))
             {

diff --git a/test/Hashids.net.test/Hashids_test.cs b/test/Hashids.net.test/Hashids_test.cs
@@ -46,6 +46,17 @@ public void AlphabetWithDashes_Encodes()
             source.Should().BeEquivalentTo(result);
         }
 
+        [Fact]
+        public void GuardCharacterOnly_DecodesToEmptyArray()
+        {
+            // no salt creates guard characters: "abde"
+            var customHashids = new Hashids("");
+            var decodedValue = customHashids.Decode("a");
+            decodedValue.Should().BeEquivalentTo(Array.Empty<int>());
+        }
+
+        [Fact]
+        private void it_has_correct_default_alphabet()
         {
             Hashids.DEFAULT_ALPHABET.Should().Be(defaultAlphabet);
         }