code: /*
   * 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.skywalking.oap.server.core.alarm.provider.expression;
  
  import org.junit.jupiter.api.Test;
  
  import java.lang.reflect.Method;
  import java.util.Arrays;
  
  import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
  
  public class ExpressionContextTest {
  
      @Test
      public void testRegisterFuncWithMethod() throws NoSuchMethodException {
          ExpressionContext expressionContext = new ExpressionContext();
          Method[] methods = Math.class.getMethods();
          Arrays.stream(methods).forEach(method -> {
              if (method.getName().equalsIgnoreCase("sqrt")) {
                  expressionContext.registerFunc("sqrt", method);
              }
          });
          Expression expression = new Expression(expressionContext);
          Number number = (Number) expression.eval("sqrt(16)");
          assertThat(number).isEqualTo(4.0);
      }
  
      @Test
      public void testRegisterFuncWithClazz() throws NoSuchMethodException {
          ExpressionContext expressionContext = new ExpressionContext();
          expressionContext.registerFunc(Math.class);
          Expression expression = new Expression(expressionContext);
          Number number = (Number) expression.eval("sqrt(16)");
          assertThat(number).isEqualTo(4.0);
          number = (Number) expression.eval("abs(-12)");
          assertThat(number).isEqualTo(12);
      }
  }
  