Revert "Temporarily move "metrics" package into impl_core/ for release. (#1426)" (#1432)

This reverts commit d3fa0e5c60903f95c184d7c7bafae8fdd12156ad.

1 files changed, 71 insertions, 0 deletions

diff --git a/api/src/test/java/io/opencensus/metrics/MetricsTest.java b/api/src/test/java/io/opencensus/metrics/MetricsTest.java
new file mode 100644
index 00000000..9e0eee1f
--- /dev/null
+++ b/api/src/test/java/io/opencensus/metrics/MetricsTest.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018, 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.metrics;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import io.opencensus.metrics.export.ExportComponent;
+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 Metrics}. */
+@RunWith(JUnit4.class)
+public class MetricsTest {
+  @Rule public ExpectedException thrown = ExpectedException.none();
+
+  @Test
+  public void loadMetricsComponent_UsesProvidedClassLoader() {
+    final RuntimeException toThrow = new RuntimeException("UseClassLoader");
+    thrown.expect(RuntimeException.class);
+    thrown.expectMessage("UseClassLoader");
+    Metrics.loadMetricsComponent(
+        new ClassLoader() {
+          @Override
+          public Class<?> loadClass(String name) {
+            throw toThrow;
+          }
+        });
+  }
+
+  @Test
+  public void loadMetricsComponent_IgnoresMissingClasses() {
+    ClassLoader classLoader =
+        new ClassLoader() {
+          @Override
+          public Class<?> loadClass(String name) throws ClassNotFoundException {
+            throw new ClassNotFoundException();
+          }
+        };
+    assertThat(Metrics.loadMetricsComponent(classLoader).getClass().getName())
+        .isEqualTo("io.opencensus.metrics.MetricsComponent$NoopMetricsComponent");
+  }
+
+  @Test
+  public void defaultExportComponent() {
+    assertThat(Metrics.getExportComponent())
+        .isInstanceOf(ExportComponent.newNoopExportComponent().getClass());
+  }
+
+  @Test
+  public void defaultMetricRegistry() {
+    assertThat(Metrics.getMetricRegistry())
+        .isInstanceOf(MetricRegistry.newNoopMetricRegistry().getClass());
+  }
+}