TestCommandShell.java

/**
 * 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.tools;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.tools.CommandShell;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class TestCommandShell {

  public class Example extends CommandShell {
    public static final String EXAMPLE = "example";
    public static final String HELLO = "hello";
    public static final String HELLO_MSG = "hello is running";
    public static final String GOODBYE = "goodbye";
    public static final String GOODBYE_MSG = "goodbye is running";

    public String[] savedArgs = null;

    @Override
    protected int init(String[] args) throws Exception {
      String command = args[0];
      if (command.equals(HELLO)) {
        setSubCommand(new Hello());
      } else if (command.equals(GOODBYE)) {
        setSubCommand(new Goodbye());
      } else{
        return 1;
      }
      savedArgs = args;
      return 0;
    }

    public String getCommandUsage() {
      return EXAMPLE;
    }

    public class Hello extends SubCommand {
      public static final String HELLO_USAGE = EXAMPLE + " hello";
      @Override
      public boolean validate() {
        return savedArgs.length == 1;
      }
      @Override
      public void execute() throws Exception {
        System.out.println(HELLO_MSG);
      }
      @Override
      public String getUsage() {
        return HELLO_USAGE;
      }
    }

    public class Goodbye extends SubCommand {
      public static final String GOODBYE_USAGE = EXAMPLE + " goodbye";
      @Override
      public void execute() throws Exception {
        System.out.println(GOODBYE_MSG);
      }
      @Override
      public String getUsage() {
        return GOODBYE_USAGE;
      }
    }
  }

  private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();

  private String outMsg(String message) {
    return "OUT:\n" + outContent.toString() + "\n" + message;
  }

  @BeforeEach
  public void setup() throws Exception {
    System.setOut(new PrintStream(outContent));
  }

  @Test
  public void testCommandShellExample() throws Exception {
    Example ex = new Example();
    ex.setConf(new Configuration());
    int rc = 0;

    outContent.reset();
    String[] args1 = {"hello"};
    rc = ex.run(args1);
    assertEquals(0, rc, outMsg("test exit code - normal hello"));
    assertTrue(outContent.toString().contains(Example.HELLO_MSG),
        outMsg("test normal hello message"));

    outContent.reset();
    String[] args2 = {"hello", "x"};
    rc = ex.run(args2);
    assertEquals(1, rc, outMsg("test exit code - bad hello"));
    assertTrue(outContent.toString().contains(Example.Hello.HELLO_USAGE),
        outMsg("test bad hello message"));

    outContent.reset();
    String[] args3 = {"goodbye"};
    rc = ex.run(args3);
    assertEquals(0, rc, outMsg("test exit code - normal goodbye"));
    assertTrue(outContent.toString().contains(Example.GOODBYE_MSG),
        outMsg("test normal goodbye message"));
  }
}