1 files changed, 85 insertions, 0 deletions
diff --git a/api/src/test/java/io/opencensus/tags/TagsTest.java b/api/src/test/java/io/opencensus/tags/TagsTest.java
new file mode 100644
index 00000000..dee517b6
--- /dev/null
+++ b/api/src/test/java/io/opencensus/tags/TagsTest.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2017, OpenCensus Authors
+ *
+ * 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 io.opencensus.tags;
+
+import static com.google.common.truth.Truth.assertThat;
+
+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 Tags}. */
+@RunWith(JUnit4.class)
+public class TagsTest {
+  @Rule public ExpectedException thrown = ExpectedException.none();
+
+  @Test
+  public void loadTagsComponent_UsesProvidedClassLoader() {
+    final RuntimeException toThrow = new RuntimeException("UseClassLoader");
+    thrown.expect(RuntimeException.class);
+    thrown.expectMessage("UseClassLoader");
+    Tags.loadTagsComponent(
+        new ClassLoader() {
+          @Override
+          public Class<?> loadClass(String name) {
+            throw toThrow;
+          }
+        });
+  }
+
+  @Test
+  public void loadTagsComponent_IgnoresMissingClasses() {
+    ClassLoader classLoader =
+        new ClassLoader() {
+          @Override
+          public Class<?> loadClass(String name) throws ClassNotFoundException {
+            throw new ClassNotFoundException();
+          }
+        };
+    assertThat(Tags.loadTagsComponent(classLoader).getClass().getName())
+        .isEqualTo("io.opencensus.tags.NoopTags$NoopTagsComponent");
+  }
+
+  // There is only one test that modifies tagging state in the Tags class, since the state is
+  // global, and it could affect other tests. NoopTagsTest has more thorough tests for tagging
+  // state.
+  @Test
+  @SuppressWarnings("deprecation")
+  public void testState() {
+    // Test that setState ignores its input.
+    Tags.setState(TaggingState.ENABLED);
+    assertThat(Tags.getState()).isEqualTo(TaggingState.DISABLED);
+
+    // Test that setState cannot be called after getState.
+    thrown.expect(IllegalStateException.class);
+    thrown.expectMessage("State was already read, cannot set state.");
+    Tags.setState(TaggingState.ENABLED);
+  }
+
+  @Test
+  public void defaultTagger() {
+    assertThat(Tags.getTagger()).isEqualTo(NoopTags.getNoopTagger());
+  }
+
+  @Test
+  public void defaultTagContextSerializer() {
+    assertThat(Tags.getTagPropagationComponent())
+        .isEqualTo(NoopTags.getNoopTagPropagationComponent());
+  }
+}