Add ZeroFormatting tests to cover zero-suppression syntax

Author: 9swampy

src/GitVersion.Core.Tests/Formatting/NumericFormatterTests.cs

@@ -35,4 +35,15 @@ public void TryFormat_UnsupportedFormat_ReturnsFalse()
         result.ShouldBeFalse();
         formatted.ShouldBeEmpty();
     }
+
+    [TestCase(0, "{0:0000}", "0000")]
+    [TestCase(1, "{0:0000}", "0001")]
+    [TestCase(0, "{0:-0000;;''}", "")]
+    [TestCase(1, "{0:-0000;;''}", "-0001")]
+    public void ZeroFormatting(int value, string template, string expected)
+    {
+        var candidate = string.Format(template, value);
+
+        Assert.That(candidate, Is.EqualTo(expected));
+    }
 }