BAEL-2541 - Guide to ProcessBuilder API

core-java/src/test/java/com/baeldung/processbuilder/ProcessBuilderUnitTest.java

@@ -0,0 +1,159 @@
+package com.baeldung.processbuilder;
+
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.empty;
+import static org.hamcrest.Matchers.hasItem;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.lang.ProcessBuilder.Redirect;
+import java.nio.file.Files;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ExecutionException;
+import java.util.stream.Collectors;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+public class ProcessBuilderUnitTest {
+
+    @Rule
+    public TemporaryFolder tempFolder = new TemporaryFolder();
+
+    @Test
+    public void givenProcessBuilder_whenInvokeStart_thenSuccess() throws IOException, InterruptedException, ExecutionException {
+        ProcessBuilder processBuilder = new ProcessBuilder("java", "-version");
+        processBuilder.redirectErrorStream(true);
+
+        Process process = processBuilder.start();
+
+        List<String> results = readOutput(process.getInputStream());
+        assertThat("Results should not be empty", results, is(not(empty())));
+        assertThat("Results should contain java version: ", results, hasItem(containsString("java version")));
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+    }
+
+    @Test
+    public void givenProcessBuilder_whenModifyEnvironment_thenSuccess() throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder();
+        Map<String, String> environment = processBuilder.environment();
+        environment.forEach((key, value) -> System.out.println(key + value));
+
+        environment.put("GREETING", "Hola Mundo");
+
+        processBuilder.command("/bin/bash", "-c", "echo $GREETING");
+        Process process = processBuilder.start();
+
+        List<String> results = readOutput(process.getInputStream());
+        assertThat("Results should not be empty", results, is(not(empty())));
+        assertThat("Results should contain a greeting ", results, hasItem(containsString("Hola Mundo")));
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+    }
+
+    @Test
+    public void givenProcessBuilder_whenModifyWorkingDir_thenSuccess() throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder("/bin/sh", "-c", "ls");
+
+        processBuilder.directory(new File("src"));
+        Process process = processBuilder.start();
+
+        List<String> results = readOutput(process.getInputStream());
+        assertThat("Results should not be empty", results, is(not(empty())));
+        assertThat("Results should contain directory listing: ", results, contains("main", "test"));
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+    }
+
+    @Test
+    public void givenProcessBuilder_whenRedirectStandardOutput_thenSuccessWriting() throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder("java", "-version");
+
+        processBuilder.redirectErrorStream(true);
+        File log = tempFolder.newFile("java-version.log");
+        processBuilder.redirectOutput(log);
+
+        Process process = processBuilder.start();
+
+        assertEquals("If redirected, should be -1 ", -1, process.getInputStream()
+            .read());
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+
+        List<String> lines = Files.lines(log.toPath())
+            .collect(Collectors.toList());
+
+        assertThat("Results should not be empty", lines, is(not(empty())));
+        assertThat("Results should contain java version: ", lines, hasItem(containsString("java version")));
+    }
+
+    @Test
+    public void givenProcessBuilder_whenRedirectStandardOutput_thenSuccessAppending() throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder("java", "-version");
+
+        File log = tempFolder.newFile("java-version-append.log");
+        processBuilder.redirectErrorStream(true);
+        processBuilder.redirectOutput(Redirect.appendTo(log));
+
+        Process process = processBuilder.start();
+
+        assertEquals("If redirected output, should be -1 ", -1, process.getInputStream()
+            .read());
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+
+        List<String> lines = Files.lines(log.toPath())
+            .collect(Collectors.toList());
+
+        assertThat("Results should not be empty", lines, is(not(empty())));
+        assertThat("Results should contain java version: ", lines, hasItem(containsString("java version")));
+    }
+
+    @Test
+    public void givenProcessBuilder_whenStartingPipeline_thenSuccess() throws IOException, InterruptedException {
+        List<ProcessBuilder> builders = Arrays.asList(
+            new ProcessBuilder("find", "src", "-name", "*.java", "-type", "f"), 
+            new ProcessBuilder("wc", "-l"));
+
+        List<Process> processes = ProcessBuilder.startPipeline(builders);
+        Process last = processes.get(processes.size() - 1);
+
+        List<String> output = readOutput(last.getInputStream());
+        assertThat("Results should not be empty", output, is(not(empty())));
+    }
+    
+    @Test
+    public void givenProcessBuilder_whenInheritIO_thenSuccess() throws IOException, InterruptedException {
+        ProcessBuilder processBuilder = new ProcessBuilder("/bin/sh", "-c", "echo hello");
+
+        processBuilder.inheritIO();
+        Process process = processBuilder.start();
+
+        int exitCode = process.waitFor();
+        assertEquals("No errors should be detected", 0, exitCode);
+    }
+
+    private List<String> readOutput(InputStream inputStream) throws IOException {
+        try (BufferedReader output = new BufferedReader(new InputStreamReader(inputStream))) {
+            return output.lines()
+                .collect(Collectors.toList());
+        }
+    }
+
+}