Allow passing a null string to TryParse

Fixes #5
devlooped · Jan 2, 2022 · 12ba476 · 12ba476
1 parent 9a7ae9e
commit 12ba476
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/src/ISBN/ISBN.cs b/src/ISBN/ISBN.cs
@@ -63,9 +63,12 @@ static ISBN()
     /// <param name="isbn">The ISBN to parse.</param>
     /// <param name="result">The parsed result, if valid.</param>
     /// <returns><see langword="false"/> if the <paramref name="isbn"/> was not a valid ISBN. <see langword="true"/> otherwise.</returns>
-    public static bool TryParse(string isbn, [NotNullWhen(true)] out ISBN? result)
+    public static bool TryParse(string? isbn, [NotNullWhen(true)] out ISBN? result)
     {
         result = default;
+        if (isbn == null)
+            return false;
+
         isbn = new string(isbn.Where(c => c != ' ' && c != '-').ToArray());
         if (isbn.Length == 10)
             isbn += "978";

diff --git a/src/Tests/ISBNTests.cs b/src/Tests/ISBNTests.cs
@@ -26,4 +26,7 @@ public void ParseIsbn(string isbn)
             Assert.True(false, "Failed to parse " + isbn);
         }
     }
+
+    [Fact]
+    public void ParseNullIsbnReturnsFalse() => Assert.False(ISBN.TryParse(null, out var _));
 }
-Original file line number
+Diff line change
@@ Expand Up / @@ -26,4 +26,7 @@ public void ParseIsbn(string isbn) @@
                 Assert.True(false, "Failed to parse " + isbn);
             }
         }
+        [Fact]
+        public void ParseNullIsbnReturnsFalse() => Assert.False(ISBN.TryParse(null, out var _));
     }