[HUDI-1149] Added a console metrics reporter and associated unit tests.

hudi-client/src/test/java/org/apache/hudi/metrics/TestHoodieConsoleMetrics.java

@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.hudi.metrics;
+
+import org.apache.hudi.config.HoodieWriteConfig;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.apache.hudi.metrics.Metrics.registerGauge;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class TestHoodieConsoleMetrics {
+
+  HoodieWriteConfig config = mock(HoodieWriteConfig.class);
+
+  @BeforeEach
+  public void start() {
+    when(config.isMetricsOn()).thenReturn(true);
+    when(config.getMetricsReporterType()).thenReturn(MetricsReporterType.CONSOLE);
+    new HoodieMetrics(config, "raw_table");
+  }
+
+  @Test
+  public void testRegisterGauge() {
+    registerGauge("metric1", 123L);
+    assertEquals("123", Metrics.getInstance().getRegistry().getGauges().get("metric1").getValue().toString());
+  }
+}