HBASE-24657 add unit test for JSONBean.java

Closes #2004

Signed-off-by: Viraj Jasani <vjasani@apache.org>

hbase-http/src/test/java/org/apache/hadoop/hbase/util/TestJSONBean.java

@@ -0,0 +1,118 @@
+/**
+ *
+ * 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.hadoop.hbase.util;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.lang.reflect.Type;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import javax.management.MBeanAttributeInfo;
+import javax.management.MBeanInfo;
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+import org.apache.hadoop.hbase.HBaseClassTestRule;
+import org.apache.hadoop.hbase.testclassification.MiscTests;
+import org.apache.hadoop.hbase.testclassification.SmallTests;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.apache.hbase.thirdparty.com.google.common.reflect.TypeToken;
+import org.apache.hbase.thirdparty.com.google.gson.Gson;
+
+/**
+ * Test {@link JSONBean}.
+ */
+@Category({MiscTests.class, SmallTests.class})
+public class TestJSONBean {
+  @ClassRule
+  public static final HBaseClassTestRule CLASS_RULE =
+    HBaseClassTestRule.forClass(TestJSONBean.class);
+
+  private MBeanServer getMockMBeanServer() throws Exception {
+    MBeanServer mbeanServer = mock(MBeanServer.class);
+    Set<ObjectName> names = new HashSet<>();
+    names.add(new ObjectName("test1:type=test2"));
+    when(mbeanServer.queryNames(any(), any())).thenReturn(names);
+    MBeanInfo mbeanInfo = mock(MBeanInfo.class);
+    when(mbeanInfo.getClassName()).thenReturn("testClassName");
+    String[] attributeNames = new String[] {"intAttr", "nanAttr", "infinityAttr",
+      "strAttr", "boolAttr"};
+    MBeanAttributeInfo[] attributeInfos = new MBeanAttributeInfo[attributeNames.length];
+    for (int i = 0; i < attributeInfos.length; i++) {
+      attributeInfos[i] = new MBeanAttributeInfo(attributeNames[i],
+        null,
+        null,
+        true,
+        false,
+        false);
+    }
+    when(mbeanInfo.getAttributes()).thenReturn(attributeInfos);
+    when(mbeanServer.getMBeanInfo(any())).thenReturn(mbeanInfo);
+    when(mbeanServer.getAttribute(any(), eq("intAttr"))).thenReturn(3);
+    when(mbeanServer.getAttribute(any(), eq("nanAttr"))).thenReturn(Double.NaN);
+    when(mbeanServer.getAttribute(any(), eq("infinityAttr"))).
+      thenReturn(Double.POSITIVE_INFINITY);
+    when(mbeanServer.getAttribute(any(), eq("strAttr"))).thenReturn("aString");
+    when(mbeanServer.getAttribute(any(), eq("boolAttr"))).thenReturn(true);
+    return mbeanServer;
+  }
+
+  private String getExpectedJSON() {
+    StringWriter sw = new StringWriter();
+    PrintWriter pw = new PrintWriter(sw);
+    pw.println("{");
+    pw.println("  \"beans\": [");
+    pw.println("    {");
+    pw.println("      \"name\": \"test1:type=test2\",");
+    pw.println("      \"modelerType\": \"testClassName\",");
+    pw.println("      \"intAttr\": 3,");
+    pw.println("      \"nanAttr\": \"NaN\",");
+    pw.println("      \"infinityAttr\": \"Infinity\",");
+    pw.println("      \"strAttr\": \"aString\",");
+    pw.println("      \"boolAttr\": true");
+    pw.println("    }");
+    pw.println("  ]");
+    pw.print("}");
+    return sw.toString();
+  }
+
+  @Test
+  public void testJSONBeanValueTypes() throws Exception {
+    JSONBean bean = new JSONBean();
+    StringWriter stringWriter = new StringWriter();
+    try (
+      PrintWriter printWriter = new PrintWriter(stringWriter);
+      JSONBean.Writer jsonWriter = bean.open(printWriter)) {
+      jsonWriter.write(getMockMBeanServer(), null, null, false);
+    }
+
+    final Gson gson = GsonUtil.createGson().create();
+    Type typeOfHashMap = new TypeToken<Map<String, Object>>() {}.getType();
+    Map<String, Object> expectedJson = gson.fromJson(getExpectedJSON(), typeOfHashMap);
+    Map<String, Object> actualJson = gson.fromJson(stringWriter.toString(), typeOfHashMap);
+    assertEquals(expectedJson, actualJson);
+  }
+}