#28: Allow clearing of environment

README.md

@@ -129,6 +129,26 @@ assertTrue(result.getOutputString().contains("var2=val 2\n"));
 assertEquals("bash -c env", result.getCommandLine());
 ~~~
 
+The environment can be cleared of values inherited from the parent process:
+
+~~~ .java
+Map<String, String> envVariables = new HashMap<>();
+envVariables.put("var1", "val 1");
+envVariables.put("var2", "val 2");
+ProcResult result = new ProcBuilder("bash")
+        .withArgs("-c", "env")
+        .clearEnvironment()
+        .withVars(envVariables).run();
+
+String[] outputLines = result.getOutputString().split("\n");
+assertEquals("var1=val 1", outputLines[0]);
+assertEquals("var2=val 2", outputLines[1]);
+// Note: environment is not going to be completely empty, as there are some variables that every process needs
+//       thus we only assert on the first two lines.
+
+assertEquals("bash -c env", result.getCommandLine());
+~~~
+
 By default the new program is spawned in the working directory of
 the parent process. This can be overidden:
 

src/main/java/org/buildobjects/process/Proc.java

@@ -35,6 +35,7 @@ class Proc implements EventSink {
     public Proc(String command,
                 List<String> args,
                 Map<String, String> env,
+                boolean clearEnvironment,
                 InputStream stdin,
                 Object stdout,
                 File directory,
@@ -54,6 +55,10 @@ public Proc(String command,
             ProcessBuilder builder = new ProcessBuilder(cmdArray)
                     .directory(directory);
 
+            if (clearEnvironment) {
+                builder.environment().clear();
+            }
+
             builder.environment().putAll(env);
             process = builder.start();
 

src/main/java/org/buildobjects/process/ProcBuilder.java

@@ -29,6 +29,7 @@ public class ProcBuilder {
 
     private StreamConsumer outputConsumer;
     private StreamConsumer errorConsumer;
+    private boolean clearEnvironment;
 
 
     /** Creates a new ProcBuilder
@@ -219,7 +220,7 @@ public ProcResult run() throws StartupException, TimeoutException, ExternalProce
         }
 
         try {
-            Proc proc = new Proc(command, args, env, stdin, outputConsumer != null ? outputConsumer : stdout , directory, timoutMillis, errorConsumer != null ? errorConsumer : stderr);
+            Proc proc = new Proc(command, args, env, clearEnvironment, stdin, outputConsumer != null ? outputConsumer : stdout , directory, timoutMillis, errorConsumer != null ? errorConsumer : stderr);
 
             final ByteArrayOutputStream output = defaultStdout == stdout && outputConsumer == null ? defaultStdout : null;
 
@@ -267,6 +268,12 @@ public static String filter(String input, String cmd, String... args) {
         return builder.run().getOutputString();
     }
 
+    /** Clears the environment before setting new variables. */
+     public ProcBuilder clearEnvironment() {
+        this.clearEnvironment = true;
+        return this;
+    }
+
     /**
      * Add a variable to the process's environment
      *
@@ -353,4 +360,5 @@ public String getProcString() {
     public String getCommandLine() {
         return Proc.formatCommandLine(command, args);
     }
+
 }

src/test/java/org/buildobjects/process/ProcBuilderTest.java

@@ -34,7 +34,7 @@
  * <dependency>
  *     <groupId>org.buildobjects</groupId>
  *     <artifactId>jproc</artifactId>
- *     <version>2.2.0</version>
+ *     <version>2.7.0</version>
  * </dependency>
  * ~~~
  */
@@ -167,6 +167,28 @@ public void testPassingInMultipleVariables() {
         assertEquals("bash -c env", result.getCommandLine());
     }
 
+    /**
+     * The environment can be cleared of values inherited from the parent process:
+     */
+    @Test
+    public void testClearEnvironment() {
+        Map<String, String> envVariables = new HashMap<>();
+        envVariables.put("var1", "val 1");
+        envVariables.put("var2", "val 2");
+        ProcResult result = new ProcBuilder("bash")
+                .withArgs("-c", "env")
+                .clearEnvironment()
+                .withVars(envVariables).run();
+
+        String[] outputLines = result.getOutputString().split("\n");
+        assertEquals("var1=val 1", outputLines[0]);
+        assertEquals("var2=val 2", outputLines[1]);
+        // Note: environment is not going to be completely empty, as there are some variables that every process needs
+        //       thus we only assert on the first two lines.
+
+        assertEquals("bash -c env", result.getCommandLine());
+    }
+
 
     /**
      * By default the new program is spawned in the working directory of