Add more tests to external code repo

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=131406104

javatests/google/registry/monitoring/metrics/LabelDescriptorTest.java

@@ -0,0 +1,50 @@
+// Copyright 2016 The Domain Registry Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.monitoring.metrics;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link LabelDescriptor}. */
+@RunWith(JUnit4.class)
+public class LabelDescriptorTest {
+
+  @Rule
+  public final ExpectedException thrown = ExpectedException.none();
+
+  @Test
+  public void testCreate_invalidLabel_throwsException() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Label name must match the regex");
+    LabelDescriptor.create("@", "description");
+  }
+
+  @Test
+  public void testCreate_blankNameField_throwsException() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Name must not be empty");
+    LabelDescriptor.create("", "description");
+  }
+
+  @Test
+  public void testCreate_blankDescriptionField_throwsException() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Description must not be empty");
+    LabelDescriptor.create("name", "");
+  }
+}