Ensure that FieldMask, Timestamp and Duration ToString() calls don't throw

The usage of ICustomDiagnosticMessage here is non-essential - ToDiagnosticString
doesn't actually get called by ToString() in this case, due to JsonFormatter code. It was
intended to make it clearer that it *did* have a custom format... but then arguably I should
do the same for Value, Struct, Any etc.

Moving some of the code out of JsonFormatter and into Duration/Timestamp/FieldMask likewise
feels somewhat nice, somewhat nasty... basically there are JSON-specific bits of formatting, but
also domain-specific bits of computation. <sigh>

Thoughts welcome.

1 files changed, 62 insertions, 0 deletions

diff --git a/csharp/src/Google.Protobuf.Test/WellKnownTypes/FieldMaskTest.cs b/csharp/src/Google.Protobuf.Test/WellKnownTypes/FieldMaskTest.cs
new file mode 100644
index 00000000..89bc8275
--- /dev/null
+++ b/csharp/src/Google.Protobuf.Test/WellKnownTypes/FieldMaskTest.cs
@@ -0,0 +1,62 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2016 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#endregion
+
+
+using NUnit.Framework;
+
+namespace Google.Protobuf.WellKnownTypes
+{
+    public class FieldMaskTest
+    {
+        [Test]
+        [TestCase("foo__bar")]
+        [TestCase("foo_3_ar")]
+        [TestCase("fooBar")]
+        public void ToString_Invalid(string input)
+        {
+            var mask = new FieldMask { Paths = { input } };
+            var text = mask.ToString();
+            // More specific test below
+            Assert.That(text, Is.StringContaining("@warning"));
+            Assert.That(text, Is.StringContaining(input));
+        }
+
+        [Test]
+        public void ToString_Invalid_Precise()
+        {
+            var mask = new FieldMask { Paths = { "x", "foo__bar", @"x\y" } };
+            Assert.AreEqual(
+                "{ \"@warning\": \"Invalid FieldMask\", \"paths\": [ \"x\", \"foo__bar\", \"x\\\\y\" ] }",
+                mask.ToString());
+        }
+    }
+}